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Parts made through additive manufacturing (AM) often exhibit mechanical anisotropy due to the time-based deposition of material and processing parameters. In polymer material extrusion (MEX), printed parts have weak points at layer interfaces, perpendicular to the direction of deposition. Poly(lactic acid) with chopped carbon fiber was printed on a large-format pellet printer at various extrusion rates with the same tool pathing to measure the fiber alignment with deposition via two methods and relate it to the ultimate tensile strength (UTS). Within a singular printed bead, an X-ray microscopy (XRM) scan was conducted to produce a reconstruction of the internal microstructure and 3D object data on the length and orientation of fibers. From the scan, discrete images were used in an image analysis technique to determine the fiber alignment to deposition without 3D object data on each fiber’s size. Both the object method and the discrete image method showed a negative relationship between the extrusion rate and fiber alignment, with −34.64% and −53.43% alignment per extrusion multiplier, respectively, as the slopes of the linear regression. Tensile testing was conducted to determine the correlation between the fiber alignment and UTS. For all extrusion rates tested, as the extrusion multiplier increased, the percent difference in the UTS decreased, to a minimum of 8.12 ± 14.40%. The use of image analysis for the determination of the fiber alignment provides a possible method for relating the microstructure to the meso-property of AM parts, and the relationship between the microstructure and the properties establishes process–structure–property relationships for large-format AM.

Parts made through additive manufacturing (AM) often exhibit mechanical anisotropy due to the time-based deposition of material and processing parameters. In polymer material extrusion (MEX), printed parts have weak points at layer interfaces, perpendicular to the direction of deposition. Poly(lactic acid) with chopped carbon fiber was printed on a large-format pellet printer at various extrusion rates with the same tool pathing to measure the fiber alignment with deposition via two methods and relate it to the ultimate tensile strength (UTS). Within a singular printed bead, an X-ray microscopy (XRM) scan was conducted to produce a reconstruction of the internal microstructure and 3D object data on the length and orientation of fibers. From the scan, discrete images were used in an image analysis technique to determine the fiber alignment to deposition without 3D object data on each fiber's size. Both the object method and the discrete image method showed a negative relationship between the extrusion rate and fiber alignment, with -34.64% and -53.43% alignment per extrusion multiplier, respectively, as the slopes of the linear regression. Tensile testing was conducted to determine the correlation between the fiber alignment and UTS. For all extrusion rates tested, as the extrusion multiplier increased, the percent difference in the UTS decreased, to a minimum of 8.12 ± 14.40%. The use of image analysis for the determination of the fiber alignment provides a possible method for relating the microstructure to the meso-property of AM parts, and the relationship between the microstructure and the properties establishes process-structure-property relationships for large-format AM.

This research introduces a comprehensive classification and analysis system tailored for accurately determining the ultimate tensile strength (UTS) of weld seams. Traditional UTS assessment methods typically depend on destructive testing, which tends to be both lengthy and expensive, limiting their continuous application in quality control of welding procedures. This study leverages deep learning techniques, segmenting the dataset into subsets for training and validation in both multi-class and binary classification scenarios. The model devised in this study incorporates cutting-edge methodologies including geometric enhancement, U-Net based image segmentation, an image augmentation of diverse deep learning models, and decision fusion tactics. A significant aspect of this research was the success of Experiment 33, which skillfully combined various methodologies, resulting in outstanding performance. This experiment demonstrated exceptional accuracy in multiclass classification, alongside impressive outcomes in binary classification, achieving a high accuracy rate of 97.4% and an F1 score of 96.5%. This level of accuracy is indicative of the average performance across all models that incorporated the He-UWA for decision fusion strategy. It encompasses the efficacy of all models using He-UWA, with or without image segmentation. These findings underscore the effectiveness of our proposed model in accurately classifying UTS in friction stir welding. This represents a crucial advancement in assessing the quality of welding processes and provides a solid foundation for future investigations in this area. [ABSTRACT FROM AUTHOR]

A machine learning-based approach is presented for predicting the mechanical properties of Cu-Ti alloys utilizing a dataset of various features, including compositional elements and processing parameters. The features encompass chemical composition elements such as Cu, Al, Ce, Cr, Fe, Mg, Ti, and Zr, as well as various thermo-mechanical processing parameters. This dataset, comprising more than 1000 data points, was selected from a larger collection of various Cu-based alloys. The dataset was divided into training, validation, and test sets, with a Random Forest Regressor model being trained and optimized using GridSearchCV. The model’s performance was evaluated based on the R2 score. The results demonstrate high predictive accuracy, with R2 scores of 0.9929, 0.9851, and 0.9937 for the training, validation, and testing sets, respectively. The Random Forest model was compared with other machine learning models and showed better results in terms of predictive accuracy. A feature importance analysis of the mechanical characteristics was conducted, further clarifying the influence of each feature. The correlation heatmap further elucidates the relationships among the features, offering insights into the effects of alloy composition and processing on mechanical properties. This study underscores the potential of machine learning in advancing the development and optimization of Cu-Ti alloys, providing a valuable tool for materials scientists and engineers.

Aluminum metal–matrix composites (AMMCs) were prepared by dispersing TiO2 dispersoids of different volume fractions into an AA6063 matrix via stir casting and subjected to process–structure correlation studies. Four different samples based on weight ratio were considered herein: 99Al-1TiO2, 97Al-3TiO2, 95Al-5TiO2, and the as-received AA6063. Their mechanical properties namely, microhardness, tensile strength, and tribological behavior, were determined. In addition, the microstructure of the samples was also analysed. It was observed that the addition of 5% TiO2 particles enabled the AA6063 matrix to accommodate a higher strain energy while providing the required driving force to generate dislocations and substructures. Therefore, considering the plastic deformation, the ultimate tensile strength σut increased gradually with the addition of TiO2 (in weight%). The flow curves of the 95Al-5TiO2 sample showed the highest value of σut, whereas the as-received AA6063 matrix exhibited the lowest value. For linear elastic deformation, AA6063 showed the lowest yield strength (σys) as compared to the AMMC samples for all TiO2 weight% values; however, the variation in σys among the AMMC samples was minimal. The microhardness of the samples increased gradually with the addition of TiO2, and the percentage reduction in area at the fracture was largest for 95Al-5TiO2. The Taguchi’s L9 array and variance analysis of the process parameters indicated that the material wear was largely affected by the normal load, followed by weight% of TiO2 and sliding speed. Wear surface characteristics, such as microvoids, delamination, microcracks, and wear debris, were qualitatively observed in all the AMMC samples. The overall strength improvement was attributable to the effects of addition of the dispersoids. During melt solidification, the TiO2 particles surpassed/pinned and hindered the grain growth, resulting in grain-size refinement.

In this work, a novel microstructure-informed machine learning (MIML) framework is proposed for the longitudinal ultimate tensile strength (UTS) evaluation and the construction of microstructure-property linkages of titanium matrix composites (TMCs). The main components of the MIML framework include (i) high-fidelity simulation and dataset generation using finite element method (FEM), (ii) the quantitative characterization of microstructures obtained by 2-point cross-correlation analysis and principal component analysis, (iii) the extraction of structure-property linkages based on support vector regression model and (iv) the validation of MIML by experimental data. The fiber breakage observed by advanced microstructure characterization is considered as the dominant failure mode during mechanical tests of TMCs, which is embedded in the FEM simulations. The MIML approach reaches capable accuracy in UTS prediction of TMCs using FEM-generated datasets and trained MIML is validated by experimental data. In addition, the permutation importance-based method is utilized to accurately identify the key feature parameters related to UTS. The first two principal components of microstructural reduced-order representation are recognized as highly relevant features for UTS. The well-trained MIML model is a promising tool in the evaluation of the mechanical property, and further provides a technical chain for the establishment of microstructure-property linkages of multi-phase composites.

The fabrication of welded joints in steel sheets has become a focal point, especially in meeting the demands for interconnections within battery packs for electric vehicles (EVs). This study delves into the impact arising from the initiation arc during the micro-tungsten inert gas (TIG) welding of nickel-plated steel sheets. The investigation involved the manipulation of various current modulations and arc lengths. Notably, optimal results were achieved with a 5 mm arc length paired with a 25 A current modulation. Microstructural analysis, conducted through scanning electron microscopy (SEM), unveiled a higher penetration depth, contributing to a more extensive and shallower fusion zone at the interface between the filler metal and the base material. Tensile testing revealed impressive mechanical properties, with the ultimate tensile strength peaking at 90 N/mm2, a yield strength of 85 N/mm2, and the highest elastic modulus. This underscores the weld’s robustness in withstanding applied loads and resisting fracture. Furthermore, the calculation of the lowest K factor at 1.0375 indicated a reduction in resistance across the specimen, resulting in enhanced conductivity. Micro-TIG welding emerges as an efficient method for nickel-plated steel in connecting individual battery cells to form a high-capacity battery pack. These interconnections ensure efficient current flow and maintain the overall integrity and performance of the battery pack. The reliability and quality of these interconnects directly affect the battery’s efficiency, safety, and lifespan in EVs application.

Structural components are generally composed of material discontinuities, including open holes, which are considered stress concentrators in engineering components. In view of this, assessing the influence of open holes on the tensile properties is crucial to determine the sensitivity and tensile strength of a particular material. Nevertheless, investigation of the impact of open holes on the tensile properties of SS400 steel sheets is very limited and yet to be explored. Therefore, this study was performed to optimize the effects of open holes on the tensile properties of SS400 sheet specimens based on a Full Factorial Design (FFD) experiment. Four input parameters that represent various hole configurations, which include the hole diameter, location of the hole, number of holes, and hole shape, were considered in this study to develop the experimental-based prediction models to optimize the output performance, namely yield strength, ultimate tensile strength, and ultimate elongation, commonly denoted as YS, UTS, and UE respectively. A total of 10 additional experimental trials were then utilized to verify the constructed models. In addition, the weight fractions for YS, UTS, and UE were identified using the Criteria Importance Through Inter-Criteria Correlation (CRITIC) method. Subsequently, the Desirability Function Analysis (DFA) is utilized to pinpoint the optimal parameter conditions for maximizing the tensile properties. Based on the results, all four parameters showed significant effects on the response variables, except the number of holes for UTS and hole location for UE. The diameter also recorded the highest contribution toward UTS and UE, followed by the hole shape. Regarding YS, hole diameter takes precedence, with the number of holes as the second most influential factor. Furthermore, the average absolute percent deviation for the prediction responses of 10 experimental cases were 1.06 %, 0.90 %, and 0.85 % for YS, UTS, and UE, respectively, confirming the validity of the constructed models. Meanwhile, the CRITIC method estimated the weight fractions for YS, UTS and UE from the experimental data, which were 0.3825, 0.2559, and 0.3616, respectively. The DFA-derived composite desirability, rated at 0.9820, suggests optimal conditions: a 1 mm hole diameter, centered hole location, three holes, and a hexagonal shape. The minimal deviations between predicted and experimental values affirm the robustness of the models. Overall, this investigation yields important insights for optimizing open holes and elevating the tensile performance of SS400 sheet specimens.

Aiming at ensuring the quality of the product and reducing the cost of steel manufacturing, an increasing number of studies have been developing nonlinear regression models for the prediction of the mechanical properties of steel rebars using machine learning techniques. Bearing this in mind, we revisit this problem by developing a design methodology that amalgamates two powerful concepts in parsimonious model building: (i) sparsity, in the sense that few support vectors are required for building the predictive model, and (ii) locality, in the sense that simpler models can be fitted to smaller data partitions. In this regard, two regression models based on the Least Squares Support Vector Regression (LSSVR) model are developed. The first one is an improved sparse version of the one introduced in a previous work. The second one is a novel local LSSVR-based regression model. The task of interest is the prediction of four output variables (the mechanical properties YS, UTS, UTS/YS, and PE) based on information about its chemical composition (12 variables) and the parameters of the heat treatment rolling (6 variables). The proposed LSSVR-based regression models are evaluated using real-world data collected from steel rebar manufacturing and compared with the global LSSVR model. The local sparse LSSVR approach was able to consistently outperform the standard single regression model approach in the task of interest, achieving improvements in the average R2 from previous studies: 5.04% for UTS, 5.19% for YS, 1.96% for UTS/YS, and 3.41% for PE. Furthermore, the sparsification of the dataset and the local modeling approach significantly reduce the number of SV operations on average, utilizing 34.0% of the total SVs available for UTS estimation, 44.0% for YS, 31.3% for UTS/YS, and 32.8% for PE.

Friction stir welding (FSW) and ultrasonic vibration enhanced FSW (UVeFSW) experiments were conducted by using 6061-T6 Al alloy and AZ31B-H24 Mg alloy sheets of thickness 2 mm. The suitable process parameters windows were obtained for the butt joining of Al/Mg sheets. The effect of ultrasonic vibration on the macrostructure and mechanical properties of the dissimilar joints was studied. The results showed that the width of the weld nugget zone (WNZ) was enlarged to some extent and the hardness distribution in WNZ was more uniform in UVeFSW. In addition, the application of ultrasonic vibration effectively promoted the interpenetration degree of dissimilar materials in the WNZ so that the mechanical interlocking on the bonding interface of dissimilar Al/Mg materials was enhanced. The facture positions were changed from the bonding interface in FSW to the boundary between WNZ and the thermo-mechanical affected zone, and the ductile fracture zone was expanded. The highest ultimate tensile strength was 205 MPa at the process parameters set of 1200 rpm–50 mm/min in UVeFSW in this experiment. The average ultimate tensile strength of FSW/UVeFSW joints was 172.3 MPa and 184.4 MPa, respectively, and the average ultimate tensile strength was increased by 7.02% with the introduction of ultrasonic vibration. [ABSTRACT FROM AUTHOR]

Aerospace industries have remained dependent on aluminium alloys for airframe structural components manufacturing due to their superior strength, fracture toughness, and ability to resist corrosion. Especially, AA2024 and AA7075 have been the most prominent and timely tested robust aluminium alloys in these manufacturing sectors. However, joining these aluminium alloys through conventional fusion welding is difficult. The present investigation focused on the mechanical and metallurgical properties of these high-strength dissimilar aluminium alloys 2024-T351 and 7075-T651 using a Friction Stir Welding (FSW) process. The effects of factors such as rotational speed RS (800–1200 rpm), welding speed WS (20–60 mm/min), and tool plunge depth (0.2–0.4 mm) on the ultimate tensile strength (UTS) and yield strength (YS) have been evaluated. The experimental procedure employed is based on RSM. The fractured surface morphology was investigated using SEM. The investigation result showed higher tensile strength (147 MPa) at the combination of welding parameters (1200 rpm, 60 mm/min, and 0.4 mm). The fabrication industries became the great beneficiaries of this emerging technology of the FSW.

Direct Metal Deposition (DMD) is a metal Additive Manufacturing (AM) process. It is used for producing sustainability Functionally Graded Materials (FGM) and repairing of sophisticated parts. In this present research, a commercially available DMD machine deposited three partial FGM blocks of size 26 mm wide × 34 mm thick × 32 mm heights. The commonly influence parameters on Ultimate Tensile Strength (UTS) are scan velocity and laser power. The powders used for deposition were Stainless Steel 316L (SS316L), Inconel 625 (IN625), and their three different compositions. ASTM E8 tensile samples were cut from those blocks by wire cut-EDM. Micro-tensile tests were carried out on ASTM E8 samples using a SHIMADZU micro-tensile machine. The results revealed that partial FGM sample-2 had high sustainability UTS of 532 MPa as compared to remaining two samples. It is illustrated that for joining two dissimilar materials to obtain high UTS thick layered (i.e., thickness more than 1 mm) gradient path method should be selected at the medium laser power available on the DMD machine. However, the sample-3 has higher hardness at high laser power.

Due to the time-consuming and costly nature of high-cycle fatigue experiments, correlations between fatigue strength and mechanical properties obtained through more simple and fast experiments can be interesting from an economic perspective. This review article aims to provide an overview of such relations established in the open literature from the 1980s to 2023 for conventionally manufactured steel grades. The majority of these models relate fatigue strength at a given fatigue life (often termed “fatigue limit” or “endurance limit”) to ultimate tensile strength, yield strength (both static and cyclic), hardness, elongation, reduction in area, and Charpy impact energy. Relations taking flaws such as nonmetallic inclusions into account are also discussed. Additionally, models predicting S–N curves are provided. The various estimations are presented in tables, together with the materials and test conditions for which they were established.

This study explores the mechanical properties of Glass Fiber-Reinforced Polymer (GFRP), a high-performance composite material, focusing on how varying diameters affect its tensile strength, modulus, and elongation. Experimental data obtained from three sets of tensile tests on 10, 12, and 25 mm bars helped establish a stress–strain relationship for GFRP reinforcements, considering diameter changes, and a formula for calculating the ultimate tensile strength based on diameter. Utilizing the weakest chain theory and the Weibull distribution, the research found that GFRP's tensile strength diminished with increased diameter, while the elastic modulus behaves oppositely. The analysis, grounded in the weakest chain theory, identifies the specimen's effective volume as a critical factor in the size effect of GFRP bars. Moreover, the study proves a significant size effect on GFRP's tensile properties, validating the theory's application in predicting the strength of GFRP bars of varying sizes and recommending a specimen length range of 30–40 times its diameter for standardization purposes. [ABSTRACT FROM AUTHOR]

As the connecting component of I-beam and UHPC, the stud is the basis of the cooperative work of each component, and is crucial to the stability and safety of the structure. To further study the shear behavior of studs in I-beam-UHPC composite structures, the push-out test was carried out by numerical simulation. The numerical simulation is in line with the load-relative slip curve and failure mode obtained by the experiment, verifying the accuracy of the numerical model. On the basis of verifying the model, the influences of the diameter, height and ultimate tensile strength of the stud on the relative slip curve, shear strength, yield strength and shear stiffness of the stud are studied. The findings indicate that a stud with a diameter of 22 mm exhibits a shear strength 156% greater than that of a stud with a diameter of 10 mm. Additionally, the yield strength increases by 135%, and the shear stiffness by 160 kN, highlighting the significant impact of stud diameter on shear resistance. When the ratio of length to diameter is less than 2.7, the shear strength of the stud increases with the height of the stud. The shear strength of a stud with a length-to-diameter ratio of 2.7 is 35% higher than that of a stud with a ratio of 1.5. The ultimate tensile strength of the stud ranges from 360 to 510 MPa, with only an 11 kN increase in yield strength, indicating that the ultimate tensile strength has a limited influence on shear properties. As the height of the stud decreases, its ultimate tensile strength gradually increases, bringing the numerical model closer to the predicted values. For shorter studs with higher ultimate tensile strength, the finite element simulation results are closer to the predicted values.Article Highlights: The numerical model can be used to study the shear properties of I-beam-UHPC composite structures. Increasing the diameter of the stud can improve the shear resistance of the stud. The higher the height of the stud, the lower the shear efficiency. When the height of the stud is smaller and the ultimate tensile strength is larger, the finite element model is closer to the predicted value. [ABSTRACT FROM AUTHOR]

As a commonly used material in the petrochemical, nuclear and aerospace fields, Inconel 625 has excellent strength and corrosion resistance. The accurate evaluation of material properties with small specimen volume is of great significance to ensure in-service equipment safety. To realize reasonable estimations of tensile strength based on the small punch test, load–displacement and slope–displacement curves of Inconel 625 were discussed in this study. The results prove that the first inflexion point can be used in the yield strength analysis based on the empirical correlation method and plate bend theory. Meanwhile, the lowest point of the elastic and plastic deformation stages in the slope–displacement curves were compared. A new deformation energy method was established to realize yield strength estimations. To analyze the ultimate tensile strength, a small punch deformation feature was discussed based on the geometric deformation model and microstructure analysis. The relationship between stress and displacement was obtained. Fm/dmt0 was proven to be a more appropriate parameter in ultimate tensile strength estimations. [ABSTRACT FROM AUTHOR]

Left ventricle leads are designed for the purpose of long-term pacing in the left ventricle. This study investigated the leads that use polyurethane as an outer insulator and SI-polyimide as an inner insulator. Polyurethane is commonly used for the outer insulation of cardiac leads due to its flexibility and biocompatibility. SI-polyimide (SI-PI) is a high-performance material known for its electrical insulation properties and is used for the inner insulation to maintain the integrity of the electrical pathways within the lead. Ten leads were received from the Wright State University Anatomical Gift Program. The duration of in vivo implantation varied for each lead, from less than a month to 108 months, with an average in vivo duration of 41 ± 31 months. We used the Test Resources Q series system for conducting our tests, as well as samples prepared to ensure compliance with the ASTM Standard D 1708-02a and the ASTM Standard D 412-06a. During the test, the load was applied to the intact lead. Before conducting individual tests, each lead was carefully inspected for surface defects. After conducting the tests, the load to failure, percentage of elongation, percentage of elongation at 5 N, ultimate tensile strength, and modulus of elasticity were calculated. There was no significant difference in load to failure, the percentage of elongation to failure, ultimate tensile strength, and modulus of elasticity (p-value = 0.82, p-value = 0.62, p-value = 0.82, and p-value = 0.12), respectively, when compared to in vivo exposure time. On the other hand, the percentage of elongation at 5 N force showed a significant difference (p-value = 0.0066) after 60 months in an in vivo environment. As the duration of in vivo exposure increased, the load to failure, percentage of elongation, ultimate tensile strength, and modulus of elasticity decreased insignificantly. The residual properties of these left ventricle leads remained relatively stable after 108 months of in vivo exposure duration, with no statistically significant degradation or changes in performance. [ABSTRACT FROM AUTHOR]

Friction stir welding was utilized to obtain high-quality SUS301L stainless steel joints, whose mechanical and corrosion properties were thoroughly evaluated. Sound joints were obtained with a wide range of rotational velocities from 400 to 700 rpm. The microstructures of the stir zone primarily consisted of austenite and lath martensite without the formation of detrimental phases. The ultimate tensile strength of the welded joints improved with higher rotational velocities apart from 400 rpm. The ultimate tensile strength reached 813 ± 16 MPa, equal to 98.1 ± 1.9% of the base materials (BMs) with a rotational velocity of 700 rpm. The corrosion resistance of the FSW joints was improved, and the corrosion rates related to uniform corrosion with lower rotational velocities were one order of magnitude lower than that of the BMs, which was attributed to the lower martensite content. However, better anti-pitting corrosion performance was obtained with a high rotational velocity of 700 rpm, which was inconsistent with the uniform corrosion results. It could be speculated that a higher martensitic content had a negative effect on the uniform corrosion performance, but had a positive effect on the improvement of the anti-pitting corrosion ability. [ABSTRACT FROM AUTHOR]

The 6935M Sprint Quattro Secure S and 6947M Sprint Quattro Secure are high voltage leads designed to administer a maximum of 40 joules of energy for terminating ventricular tachycardia or ventricular fibrillation. Both leads utilize silicone insulation and a polyurethane outer coating. The inner coil is shielded with polytetrafluoroethylene (PTFE) tubing, while other conductors are enveloped in ethylene tetrafluoroethylene (ETFE), contributing to the structural integrity and functionality of these leads. Polyurethane is a preferred material for the outer insulation of cardiac leads due to its flexibility and biocompatibility, while silicone rubber ensures chemical stability within the body, minimizing inflammatory or rejection responses. Thirteen implantable cardioverter defibrillator (ICD) leads were obtained from the Wright State University Anatomical Gift Program. The as-received devices exhibited varied in vivo implantation durations ranging from less than a month to 89 months, with an average in vivo duration of 41 ± 27 months. Tests were conducted using the Test Resources Q series system, ensuring compliance with ASTM Standard D 1708-02a and ASTM Standard D 412-06a. During testing, a load was applied to the intact lead, with careful inspection for surface defects before each test. Results of load to failure, percentage elongation, percentage elongation at 5 N, ultimate tensile strength, and modulus of elasticity were calculated. The findings revealed no significant differences in these parameters across all in vivo exposure durations. The residual properties of these ICD leads demonstrated remarkable stability and performance over a wide range of in vivo exposure durations, with no statistically significant degradation or performance changes observed. [ABSTRACT FROM AUTHOR]

Process parameter optimization and selection play a crucial role in additive manufacturing, particularly in determining the quality and characteristics of the final product. Among these parameters, the infill pattern holds significant importance as it directly influences the structural integrity, production time, and material usage efficiency of the printed object. This research focuses on identifying the most suitable 3D printing infill pattern process parameters for thermoplastic polyurethane (TPU) material, specifically for applications in pipeline construction. The criteria considered for process parameter selection include printing time, ultimate tensile strength, ultimate flexural strength, and surface defect minimization. Various infill patterns, including hexagonal, line, solid, triangle (35°), triangle (55°), and line patterns, are evaluated as alternatives. Utilizing the multi‐criteria decision‐making technique known as analytical hierarchy process (AHP), a systematic approach is employed to determine the optimal printing pattern. The findings of this study reveal that the hexagonal infill pattern outperforms other selected patterns in terms of meeting the criteria set forth for pipeline construction using TPU material. This research contributes to enhancing the efficiency and quality of additive manufacturing processes in pipeline applications, emphasizing the importance of informed parameter selection for achieving desired performance outcomes. [ABSTRACT FROM AUTHOR]

Electrospinning is an outstanding manufacturing technique for producing nano-micro-scaled fibrous scaffolds comparable to biological tissues. However, the solvents used are normally hazardous for the health and the environment, which compromises the sustainability of the process and the industrial scaling. This novel study compares different machine learning models to predict how green solvents affect the morphology, topography and mechanical properties of gelatin-based scaffolds. Gelatin-based scaffolds were produced with different concentrations of distillate water (dH2O), acetic acid (HAc) and dimethyl sulfoxide (DMSO). 2214 observations, 12 machine learning approaches, including Generalised Linear Models, Generalised Additive Models, Generalised Additive Models for Location, Scale and Shape (GAMLSS), Decision Trees, Random Forest, Support Vector Machine and Artificial Neural Network, and a total of 72 models were developed to predict diameter of the fibres, inter-fibre separation, roughness, ultimate tensile strength, Young's modulus and strain at break. The best GAMLSS models improved the performance of R2 with respect to the popular regression models by 6.868%, and the MAPE was improved by 21.16%. HAc highly influenced the morphology and topography; however, the importance of DMSO was higher in the mechanical properties. The addition of the morphological properties as covariates in the topographic and mechanical models enhanced their understanding. [ABSTRACT FROM AUTHOR]

Background: Laser metal deposition (LMD) is a widely used additive manufacturing technique for producing complex high entropy alloys with special properties for several applications. The AlCoCrFeNiCu HEAs compositional design has six elements with a configurational entropy of 1.79 R and atomic concentrations between 5 and 35%, so the HEA system is thermodynamically favorable according to Boltzmann's theory, attributed to the core effects. However, the high-entropy alloy has dominant Body-Centered Cubic structures which may be too brittle to be examined in tension experimentally. Preheating the substrate before and during layer deposition could be a potential solution that is currently under development since tensile loading necessitates an understanding of a material's behavior under tension through an analysis of its yield and ultimate tensile strength. A computer-aided design (CAD) solid model was used to generate the near-net dog-bone form of the alloy with moderately complicated geometrical characteristics using laser metal deposition (LMD) technology. This study investigates a straightforward and effective computational model for simulating material properties, using COMSOL Multiphysics 5.4 software for laser-deposited high entropy alloys that are excessively brittle to be tested in tension. The AlCoCrFeNiCu high-entropy alloy "dog bone" test sample was modeled using COMSOL Multiphysics for tensile loading. The first principal stresses and longitudinal strain under axial loading conditions were measured using a three-dimensional (3D) structural mechanics' model. Results: The results showed the ultimate tensile strength is 8.47 N/m2, attributed to the high entropy effect and the dominant phase structure of the alloy. Conclusion: Numerical models in this paper demonstrate the effect of stresses on the tensile behavior of the AlCoCrFeNiCu high-entropy alloy. The model optimizes the LMD process by analyzing residual stresses and predicting tensile strength, thus, providing insights that show the potential of high entropy alloys for structural integrity in aerospace applications. [ABSTRACT FROM AUTHOR]

A theory model with two kinds of material, which are used to describe the axis stress strain relationship of the pipe segment and girth weld joints, is proposed for the pipeline axial deformation analysis, and a pipeline deformation diagram is composed for the axis deformation combination within the pipeline design limit. According to the pipeline deformation diagram, it is found that the strength of the pipe segment at the design limit σAb plays a key role in the strength matching discussion. The pipeline axis deformation could be classified as three categories based on the yield strength σYw, ultimate tensile strength σcritw of the weld joints and the pipe design strength σAb, which are σYw>σAb, σcritw≥ σAb≥σYw and σAb>σcritw . For σYw>σAb, the axis plastic deformation will distribute along the pipe segment and this is the ideal states for the pipeline. For σAb>σcritw, the girth weld may fail as stress rupture with tensile strain as low as 0.003. For σcritw≥ σAb≥ σYw, the weld joint may endure the plastic deformation, and the material properties of the weld joint may change, such as the toughness may decrease. Charpy-V impact test have shown that the toughness decreases 35 % for 2 % deformation for the weld joints welded by FCAW-S. In this scenario, the girth weld may break up as brittle fracture due to the toughness decrease. This model could be used to explain the girth weld failures, optimize the strength matching and control the risk, especially for the buried high strength pipeline of the high stress locations. [ABSTRACT FROM AUTHOR]

This study investigates the potential use of Yellow River sand (YRS) sourced from the lower reaches of the Yellow River in China as a sustainable and cost-effective substitute for quartz sand in Engineered Cementitious Composites (ECC). With an annual accumulation of approximately 400 million tons in this region, YRS presents a substantial resource. ECC specimens with 100% YRS replacement with quartz sand were subjected to various curing methods: natural, steam, standard, and sprinkler. Extensive mechanical testing including flexural, compressive, uniaxial tensile, and four-point flexural tests was conducted. Additionally, Scanning Electron Microscope (SEM) and Mercury Intrusion Porosimetry (MIP) analyses investigated microscopic mechanisms influencing macroscopic mechanical properties. Finally, the mechanical properties of the YRS-ECC test block after 14 days of standard curing and the traditional sand ECC test block were compared and analyzed. The results indicate that ECC specimens with 100% YRS substitution under natural curing show an optimal ultimate tensile strain of more than 4%, providing the best resistance to the reduction in ultimate flexural load and deflection due to aging. Steam curing enhances flexural and compressive strength, achieving an ultimate flexural load of 5 kN and a maximum deflection of 4.42 mm at 90 days. SEM analysis revealed lower C-S-H gel density under natural curing and higher under steam curing, enhancing fiber pull-out in steam-cured specimens. The MIP tests demonstrated that natural curing had the highest porosity (32.86%) and average pore size (51.69 nm), whereas steam curing resulted in the smallest average pore size, with 44% of pores under 50 nm. Compared with traditional sand, it is found that the ultimate bending load and deflection of YRS-ECC are 5.7% and 9.4% higher than those of traditional sand ECC, respectively, and its ultimate tensile strength and strain are also improved. These findings highlight YRS as a sustainable alternative to natural sand in ECC, with natural curing proving the most effective for superior mechanical performance, including tensile strain, crack resistance, and durability. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the tribological characteristics of commercially available high-strength polyphthalamide-based composites with great contents (30–50 wt.%) of both carbon and glass fibers in point and linear contacts against metal and ceramic counterfaces under dry friction and oil-lubricated conditions at various loads and sliding speeds. The lengths of both types of fibers were varied simultaneously with their contents while samples were fabricated from granules by injection molding. When loading PPA with 30 wt.% SCFs at an aspect ratio (AR) of 200, the ultimate tensile strength and the elastic modulus increased up to 142.7 ± 12.5 MPa and 12.9 ± 0.6 GPa, respectively. In the composites with the higher contents of reinforcing fibers PPA/40CCF and AR~1000, the ultimate tensile strength and the elastic modulus were 240 ± 3 MPa and 33.7 ± 1.9 GPa, respectively. Under the applied test conditions, a composite reinforced with 40 wt.% carbon fibers up to 100 μm long at an aspect ratio of ~1000 possessed the best both mechanical properties and tribological characteristics. One of the reasons that should be considered for improving the tribological characteristics of the composite is the fatigue wear mechanism, which is facilitated by the high filling degree, the strong interfacial adhesion, and the great aspect ratio for fibers. Under the oil-lubricated conditions, both friction coefficients and wear rates decreased, so such friction units could be implemented whenever possible. The reported data can be used as practical recommendations for applying fibrous polyphthalamide-based composites as friction unit components. [ABSTRACT FROM AUTHOR]

This study investigates the effects of post-weld heat treatment (PWHT) on the microstructures and mechanical properties of plasma arc-welded 316 stainless steel. The experimental parameters included the solid solution temperatures of 650 °C and 1050 °C, solid solution durations of 1 h and 4 h, and quenching media of water and air. The mechanical properties were evaluated using Vickers hardness testing, tensile testing, scanning electron microscopy (SEM), and optical microscopy (OM). The highest ultimate tensile strength (UTS) of 693.93 MPa and Vickers hardness of 196.4 in the welded zone were achieved by heat-treating at 650 °C for one hour, quenching in water, and aging at 500 °C for 24 h. Heat-treating at 650 °C for one hour, followed by quenching in water and aging at 500 °C for 24 h results in larger dendritic δ grains and contains more σ phase compared to the other conditions, resulting in increased strength and hardness. Additionally, it shows wider and shallower dimple structures, which account for its reduced impact toughness. [ABSTRACT FROM AUTHOR]

The friction stir welding (FSW) method was used to weld B4C reinforced AA 5083 metal matrix composites in this study. By coating titanium nitride (TiN), aluminium chromium nitride (AlCrN), and diamond-like carbon (DLC) to a thickness of 4 microns, three FSW tools with square pin profiles were developed and the friction coefficients of 0.69, 0.32, and 0.2 were maintained. At three levels, the process factors such as tool rotating speed, transverse feed, and axial force were examined. For each tool, 15 samples were made using the central composite design. The influence of the friction coefficient on ultimate tensile strength, microstructural features, and tool condition was studied, and the flower pollination algorithm (FPA) technique was used to find the best process parameters for obtaining maximum ultimate tensile strength of FSW joints. The improved tensile strength of FSW joints was verified using a validation test. The coating has a considerable influence on the ultimate tensile strength, microstructure, and tool condition, according to the results of the tool's friction coefficient. The results on the prediction of strength using the fuzzy clustering technique showed that the technique is effective in predicting the tensile strength values, with the root mean square error (RSME) of TiN, AlCrN, and DLC being 0.0027, 0.0016, and 0.0015, respectively, and the low RSME indicating that the prediction based on the fuzzy subtractive clustering technique is perfect and effective. [ABSTRACT FROM AUTHOR]

The stability of riverbank slopes is crucial in watershed ecology. The morphology and tensile strength properties of plant roots play a significant role in slope stability, which is of great importance for the ecological stability of riverbanks. The Jinsha and Yalong River basins are the largest hydropower bases in China and are in the ecologically fragile areas of the dry and hot river valleys, yet fewer studies are available on these basins. Further studies on the growth morphology and root mechanical properties of plant roots in the riparian zone at different elevations have not been reported. Therefore, we selected the dominant species of Cynodon dactylon root as the research subject, analyzed the root morphology, and conducted indoor single-root tensile tests to study its root structure and mechanical properties at various elevations. The results showed that the root morphology of Cynodon dactylon was positively correlated with elevation. Compared to low elevations (L and M), the root length increased by 57.3% and 21.47%, the root diameter increased by 24.85% and 13.92%, the root surface area increased by 93.5% and 67.37%, and the total root volume increased by 119.91% and 107.36%. As the elevation gradient increased, the flooding time decreased, leading to more developed plant roots for Cynodon dactylon. The Young's modulus ranged from 148.43 to 454.18 MPa for Ertan Cynodon dactylon roots and 131.31 to 355.53 MPa for Guanyingyan Cynodon dactylon roots. The maximum tensile strength, ultimate tensile strength, ultimate elongation, and Young's modulus of the plant root of the Cynodon dactylon showed a power function relationship with the diameter. The maximum tensile strength increased as the diameter increased, while the remaining properties decreased following a power function relationship. The maximum tensile strength, ultimate tensile strength, and Young's modulus of Cynodon dactylon were positively correlated with elevation, while the ultimate elongation was negatively correlated with elevation. The results elucidate the influence of elevation on the root morphology and mechanical properties of dominant riparian species. This provides a theoretical basis for managing and protecting riparian slopes in ecologically fragile areas. [ABSTRACT FROM AUTHOR]

Copyright of FME Transactions is the property of University of Belgrade, Faculty of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To keep up with the growing demand for composites in fields like medicine, transportation, safety, and athletics, researchers constantly create new composites. These experiments examined the impact of boron carbide filler particles in epoxy by making composites out of Lapox L-12 epoxy with 5, 10, and 15 percent boron carbide fillers using the hand layup technique. The mechanical properties of the prepared composites were measured as per ASTM standards, including hardness, ultimate tensile strength, yield strength, elongation, and flexural strength. Further, wear behavior of prepared composites was evaluated as ASTM G99 standard with varying loads and speeds. Hardness, tensile and flexural strength were increased with a slight decrease in percentage elongation after boron carbide filler particles were added to epoxy Lapox L-12. Lapox L-12 with boron carbide fillers reinforced composites were shown an improvement of 56.4% in hardness, 52.5% in ultimate strength and 25.85% improvements in the flexural strength. The wear behaviour of epoxy and its composites were affected by applied load and speeds. However, Lapox L-12 with boron carbide fillers reinforced composites exhibits higher wear resistance with smooth worn surface morphologies. The improvement in the tensile and wear behavior of L-12 epoxy with B4C composites can be utilized for several applications like air intake duct and air intake lip of an aircraft. [ABSTRACT FROM AUTHOR]

Aluminum metal-matrix composites (AMMCs) were prepared by dispersing TiO2 dispersoids of different volume fractions into an AA6063 matrix via stir casting and subjected to process-structure correlation studies. Four different samples based on weight ratio were considered herein: 99Al-1TiO2, 97Al-3TiO2, 95Al-5TiO2, and the as-received AA6063. Their mechanical properties namely, microhardness, tensile strength, and tribological behavior, were determined. In addition, the microstructure of the samples was also analysed. It was observed that the addition of 5% TiO2 particles enabled the AA6063 matrix to accommodate a higher strain energy while providing the required driving force to generate dislocations and substructures. Therefore, considering the plastic deformation, the ultimate tensile strength (sut) increased gradually with the addition of TiO2 (in weight%). The flow curves of the 95Al-5TiO2 sample showed the highest value of sut, whereas the as-received AA6063 matrix exhibited the lowest value. For linear elastic deformation, AA6063 showed the lowest yield strength (sys) as compared to the AMMC samples for all TiO2 weight% values; however, the variation in sys among the AMMC samples was minimal. The microhardness of the samples increased gradually with the addition of TiO2, and the percentage reduction in area at the fracture was largest for 95Al-5TiO2. The Taguchi's L9 array and variance analysis of the process parameters indicated that the material wear was largely affected by the normal load, followed by weight% of TiO2 and sliding speed. Wear surface characteristics, such as microvoids, delamination, microcracks, and wear debris, were qualitatively observed in all the AMMC samples. The overall strength improvement was attributable to the effects of addition of the dispersoids. During melt solidification, the TiO2 particles surpassed/pinned and hindered the grain growth, resulting in grainsize refinement. [ABSTRACT FROM AUTHOR]

This study addresses a research gap in composite material development by exploring the potential of innovative waste materials to enhance performance. An innovative and cost‐effective waste material serves as a reinforcing agent, with cenosphere and molybdenum disulphide used in proportions ranging from 0% to 4%. Employing a cost‐effective stirring cast technique, composites are fabricated, combining AA7075 alloy with cenosphere particles (AA7075/cenosphere) and molybdenum disulphide particles (AA7075/MoS2). The experimental design, utilizing a central composite design within the response surface methodology framework, examines the weight percentages of cenosphere and MoS2. Scanning electron microscopy reveals strengthening chemicals within the matrix, confirmed by electronic dispersive X‐ray spectroscopy for individual reinforcements in the aluminium alloy matrix. Density determination follows Archimedes' principle and the OIML G14 standard, while mechanical properties (hardness and ultimate tensile strength) are assessed per ASTM standards. Results demonstrate a significant reduction in composite density with cenosphere reinforcement, while molybdenum disulphide marginally affects density. The incorporation of reinforcements notably enhances both hardness and ultimate tensile strength. In conclusion, this research bridges a composite material development gap, presenting a novel and sustainable approach. By showcasing the potential of unconventional waste materials, the study contributes valuable insights to material science and engineering, opening new avenues for future research. [ABSTRACT FROM AUTHOR]

The emergence of biodegradable stents addresses the limitations of the long-term presence of permanent bare metal stents in the human body. Following implantation, these stents can significantly reduce the occurrence of chronic complications such as inflammation and thrombosis, thus becoming a mainstream approach in the treatment of interventional cardiovascular diseases. Currently, the materials used for biodegradable stents are typically polymers. However, the inherent properties of the materials dictate that polymer stents exhibit lower mechanical performance and biocompatibility. Magnesium alloy materials, on the basis of their biodegradability, exhibit superior mechanical performance when compared to polymers, possessing the potential to address this issue. However, the presence of stress concentration in the stent structure necessitates further designs and mechanical performance analyses of magnesium alloy stents. In this work, a biodegradable stent based on WE43 alloy is designed. The stent incorporates the micro-protrusion structure to enhance the mechanical performance. Furthermore, to evaluate the clinical applicability of the stent, the mechanical performance of the biodegradable magnesium alloy stent is conducted through finite element analysis (FEA). The results show that the maximum equivalent stress in all four aspects is below the ultimate tensile strength of 370 MPa for the WE43 magnesium alloy, demonstrating excellent mechanical performance. Additionally, after crimping and expansion, the radial support strength and radial support force reached 780 mN/mm and 1.56 N, respectively. Compared to the advanced reported stent structures, the radial support strength and radial support force are enhanced by 13% and 47%, respectively. Additionally, flexibility analysis indicated that the flexibility of the stent design in this study is improved by a factor of 9.76, ensuring the stent's capability to navigate through complex vasculature during implantation. [ABSTRACT FROM AUTHOR]

The thermal properties, microstructure, and mechanical properties of Fe-18Mn-3Ti (wt%) were investigated, focusing on the effects of different heat-treatment processes. Results revealed that the 450 °C warm-rolling sample (450 WR) exhibited promising mechanical properties. Specifically, this sample displayed a yield strength of 988 MPa, an ultimate tensile strength of 1052 MPa, and total elongation of 15.49%. Consequently, a favorable strength-ductility balance was achieved. The strain-hardening ability surpassed that of the cold rolling sample (CR). Microstructure analysis indicated the simultaneous occurrence of dynamic equilibrium between grain deformation and re-crystallization because of the co-influence of thermal and strain in the warm rolling process. This desirable mechanical property was attributed to the presence of a multi-phase (α-martensite, austenite, and ε-martensite) and heterogeneous microstructure. The improvement of ultimate tensile strength was based on grain refinement, grain co-deformation, and the transformation-induced plasticity (TRIP) effect in the early stage of plastic deformation (stage Ⅰ). The improvement of ultimate elongation (TEL) was ascribed to the TRIP effect in the middle stage of plastic deformation (stage Ⅱ). [ABSTRACT FROM AUTHOR]

To address the issue of pavement cracking due to brittle concrete in road and bridge engineering, this study explores the use of high–ductility magnesium phosphate cementitious concrete (HD–MPCC) for rapid repairs. The deformation and frost properties of HD–MPCC are analyzed to assess its suitability for this application. Deformation properties were tested for HD–MPCC specimens cured in both air and water. Subsequent tests focused on the frost performance and mechanical properties after freeze–thaw cycles. A mercury penetration technique was utilized to examine the pore structure. The findings reveal that the expansion deformation of HD–MPCC increases with curing age in both air and water conditions, and the quantitative relationship between the expansion deformation and curing age of HD–MPCC was analyzed. Additionally, the freeze–thaw cycles led to a decrease in mass loss, the relative dynamic elastic modulus, the ultimate tensile strength, the ultimate tensile strain, the flexural strength, and the peak deflection. The volume fraction of harmless and less harmful pores gradually decreased as the freeze–thaw cycle increased, while the volume fraction of more harmful pores increased, resulting in a decrease in the strength, ultimate tensile strain, and peak deflection. [ABSTRACT FROM AUTHOR]

When the cocoa pod husk (CPH) is used and processed, two types of flour were obtained and can be differentiated by particle size, fine flour (FFCH), and coarse flour (CFCH) and can be used as a possible reinforcement for the development of bio-based composite materials. Each flour was obtained from chopping, drying by forced convection, milling by blades, and sieving using the 100 mesh/bottom according to the Tyler series. Their physicochemical, thermal, and structural characterization made it possible to identify the lower presence of lignin and higher proportions of cellulose and pectin in FFCH. Based on the properties identified in FFCH, it was included in the processing of thermoplastic starch (TPS) from the plantain pulp (Musa paradisiaca) and its respective bio-based composite material using plantain peel short fiber (PPSF) as a reinforcing agent using the following sequence of processing techniques: extrusion, internal mixing, and compression molding. The influence of FFCH contributed to the increase in ultimate tensile strength (7.59 MPa) and higher matrix–reinforcement interaction when obtaining the freshly processed composite material (day 0) when compared to the bio-based composite material with higher FCP content (30%) in the absence of FFCH. As for the disadvantages of FFCH, reduced thermal stability (323.57 to 300.47 °C) and losses in ultimate tensile strength (0.73 MPa) and modulus of elasticity (142.53 to 26.17 MPa) during storage progress were identified. In the case of TPS, the strengthening action of FFCH was not evident. Finally, the use of CFCH was not considered for the elaboration of the bio-based composite material because it reached a higher lignin content than FFCH, which was expected to decrease its affinity with the TPS matrix, resulting in lower mechanical properties in the material. [ABSTRACT FROM AUTHOR]

The human heart's remarkable vitality necessitates a deep understanding of its mechanics, particularly concerning cardiac device leads. This paper presents advancements in finite element modeling for cardiac leads and 3D heart models, leveraging computational simulations to assess lead behavior over time. Through detailed modeling and meshing techniques, we accurately captured the complex interactions between leads and heart tissue. Material properties were assigned based on ASTM (American Society for Testing and Materials) standards and in vivo exposure data, ensuring realistic simulations. Our results demonstrate close agreement between experimental and simulated data for silicone insulation in pacemaker leads, with a mean force tolerance of 19.6 N ± 3.6 N, an ultimate tensile strength (UTS) of 6.3 MPa ± 1.15 MPa, and a percentage elongation of 125% ± 18.8%, highlighting the effectiveness of simulation in predicting lead performance. Similarly, for polyurethane insulation in ICD leads, we found a mean force of 65.87 N ± 7.1 N, a UTS of 10.7 MPa ± 1.15 MPa, and a percentage elongation of 259.3% ± 21.4%. Additionally, for polyurethane insulation in CRT leads, we observed a mean force of 53.3 N ± 2.06 N, a UTS of 22.11 MPa ± 0.85 MPa, and a percentage elongation of 251.6% ± 13.2%. Correlation analysis revealed strong relationships between mechanical properties, further validating the simulation models. Classification models constructed using both experimental and simulated data exhibited high discriminative ability, underscoring the reliability of simulation in analyzing lead behavior. These findings contribute to the ongoing efforts to improve cardiac device lead design and optimize patient outcomes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Additive manufacturing (AM) is now widely used for research and industrial production. The benchmark data for mechanical properties of additively manufactured specimens is very useful for many communities. This data article presents a tensile testing dataset of ASTM D638 size specimens without and with embedded internal geometrical features printed using polylactic acid (PLA) in a Fused Filament Fabrication (FFF) additive manufacturing process. The added features can mimic defects of various shapes and sizes. This work is a supplement to the published research article Assisted defect detection by in-process monitoring of additive manufacturing using optical imaging and infrared thermography (Additive Manufacturing, 2023, 103483). The printed specimens were tensile tested. Stress-strain graphs were developed and used to calculate the mechanical properties such as ultimate tensile strength (UTS) and strain at UTS. The mechanical properties, the correlations between mechanical properties and size, shape and location of geometrical features (defects), and the trends in mechanical properties can be useful in benchmarking the results of other researchers. [ABSTRACT FROM AUTHOR]

Aero-engines can be exposed to One Engine Inoperative (OEI) conditions during service, and the resulting overheating effect may significantly impact their structural integrity and flight safety. This paper focuses on the influence of overheating on the microstructural evolution and tensile properties of the GH4720Li alloy, a nickel-based polycrystalline superalloy commonly used in turbine disks. Based on the typical OEI operating conditions of a real aero-engine, a series of non-isothermal high-temperature tensile tests involving an OEI stage of 800 °C were conducted. The effects of OEI-induced overheating on the microstructure and tensile properties of the GH4720Li alloy were investigated. The results showed that, after OEI treatment, the primary γ′ phase in this alloy was partially dissolved. The GH4720Li superalloy also exhibited numerous microcracks at the grain boundaries, resulting in complex effects on its tensile properties. The alloy's yield strength and ultimate tensile strength were slightly decreased, whereas its ductility decreased considerably. The OEI-induced embrittlement phenomenon was mainly caused by the non-uniform distribution of the tertiary γ′ phase within grains. The formation of microcracks nucleated at the interfaces between the primary γ′ precipitates and γ matrix phase was another key factor. [ABSTRACT FROM AUTHOR]

The primary focus of the current paper centers on the microstructures and mechanical properties exhibited by a Ti-30Nb-12Zr-5Ta-2Sn-1.25Fe (wt. %) (TNZTSF) alloy that has been produced through an intricate synthesis process comprising cold-crucible induction in levitation, carried out in an atmosphere controlled by argon, and cold-rolling deformation (CR), applying systematic adjustments in the total deformation degree (total applied thickness reduction), spanning from 10% to 60%. The microstructural characteristics of the processed specimens were investigated by SEM and XRD techniques, and the mechanical properties by tensile and microhardness testing. The collected data indicate that the TNZTSF alloy's microstructure, in the as-received condition, consists of a β-Ti phase, which shows polyhedral equiaxed grains with an average grain size close to 82.5 µm. During the cold-deformation processing, the microstructure accommodates the increased applied deformation degree by increasing crystal defects such as sub-grain boundaries, dislocation cells, dislocation lines, and other crystal defects, powerfully affecting the morphological characteristics. The as-received TNZTSF alloy showed both high strength (i.e., ultimate tensile strength close to σUTS = 705.6 MPa) and high ductility (i.e., elongation to fracture close to εf = 11.1%) properties, and the computed β-Ti phase had the lattice parameter a = 3.304(7) Å and the average lattice microstrain ε = 0.101(3)%, which are drastically influenced by the applied cold deformation, increasing the strength properties and decreasing the ductility properties due to the increased crystal defects density. Applying a deformation degree close to 60% leads to an ultimate tensile strength close to σUTS = 1192.1 MPa, an elongation to fracture close to εf = 7.9%, and an elastic modulus close to 54.9 GPa, while the computed β-Ti phase lattice parameter becomes a = 3.302(1) Å. [ABSTRACT FROM AUTHOR]

We used powder hot extrusion followed by annealing to fabricate a dual-phase AlCoCrFeNi2.1 eutectic high-entropy alloy consisting of both non-recrystallized and recrystallized grains with dense nano-sized precipitates arranged in heterogeneous structures. The resulting alloy exhibits superior tensile properties with a yield strength of ∼1.2 GPa, an ultimate tensile strength of ∼1.5 GPa, and a uniform elongation of ∼18%. Such multiscale microstructure results in exceptional strain hardening of the AlCoCrFeNi2.1 alloy by activating remarkable hetero-deformation induced (HDI) stresses. Our study provides an effective approach to fabricating high-performance structural materials via dual-phase heterogeneous microstructure design. [ABSTRACT FROM AUTHOR]

Deep cryogenic aging (DCA) is a newly developed heat treatment technique for additive-manufactured metallic materials to reduce residual stress and improve their mechanical properties. In this study, AlSi10Mg alloy samples fabricated by selective laser melting were deep-cryogenic-treated at −160 °C and subsequently aged at 160 °C. Phase and microstructural analyses were conducted using X-ray diffraction, optical microscopy, scanning electron microscopy, and transmission electron microscopy, while the mechanical properties were evaluated through microhardness and tensile testing at room temperature. The results indicated that the DCA treatment did not have an effect on the morphology of the melt pools. However, it facilitated the formation of atomic clusters and nanoscale Si and β′ phases, as well as accelerating the coarsening of grains and the ripening of the eutectic Si phase. After DCA treatment, the mass fraction of the Si phase experienced an increase from 4.4% to 7.2%. Concurrently, the volume fraction of the precipitated secondary phases elevated to 5.1%. The microhardness was enhanced to 147 HV, and the ultimate tensile strength and yield strength achieved 495 MPa and 345 MPa, respectively, with an elongation of 7.5%. In comparison to the as-built specimen, the microhardness, ultimate tensile strength, and yield strength increased by 11.4%, 3.1%, and 19.0%, respectively. The improvement in mechanical properties is primarily attributed to the Orowan strengthening mechanism induced by the secondary phases. [ABSTRACT FROM AUTHOR]

This study investigates the enhancement of mechanical properties of metal/polymer composites produced through fused deposition modeling and the prediction of the ultimate tensile strength (UTS) by machine learning using a Classification and Regression Tree (CART). The composites, comprising 80% acrylonitrile butadiene styrene matrix and 10% each of aluminum (Al) and copper (Cu) fillers, were subjected to a comprehensive exploration of printing parameters, including printing temperature, infill pattern, and infill density using the Taguchi method. The CART unveiled a hierarchical tree structure with four terminal nodes, each representing distinct subgroups of materials characterized by similar UTS properties. The predictors' importance was assessed, highlighting their role in determining material strength. The model exhibited a high predictive power with an R-squared value of 0.9154 on the training data and 0.8922 on the test data, demonstrating its efficacy in capturing variability. The optimal combination of parameters for maximizing UTS was a zigzag infill pattern, a printing temperature of 245 °C, and an infill density of 10%, which is associated with the highest UTS of 680 N. The model's reliability was confirmed through a paired t-test and test and confidence interval for two variances, revealing no significant difference between the observed and predicted UTS values. This research contributes to advancing additive manufacturing processes by leveraging CART analysis to optimize printing parameters and predict material strength. The identified optimal conditions and subgroup characteristics pave the way for developing robust and predictable metal/polymer composites, offering valuable insights for material design in the era of advanced manufacturing technologies. [ABSTRACT FROM AUTHOR]