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One-step (F100) and three-step (F30-60-40) hot forging of Al0.35CoCrFeNi alloy was investigated to achieve a uniform equiaxed grain structure. In the as-cast and forged state, only a single-phase face-centered cubic structure was observed. The formation of twins, recrystallized and partially recrystallized grains in the volume of the samples was observed depending on used forging process. To predict uniform grain-size formation numerical simulation of the hot-forging process was used. The numerical model was calibrated and validated by means of measured compression experimental data of as-cast Al0.35CoCrFeNi alloy before forging. Thermal analysis using finite element analysis was used to simulate cooling of sample during the relocation from the furnace on the lower die. Simulations were run under different thermo-mechanical conditions and the regions for the formation of dynamically recrystallized grains were predicted. Room temperature mechanical properties were evaluated after F100 and F30-60-40 hot-forging process. The F30-60-40 hot forging optimized the grain size, which was evident in the very small dispersion of the room temperature mechanical properties in tension. Elongation after F30-60-40 hot forging increased by 17%. The correlation between temperature, equivalent stress, equivalent plastic strain, microstructure, tensile properties, and strain-hardening behavior is discussed. [ABSTRACT FROM AUTHOR]

Numerical simulations are crucial for predicting outcomes in forging processes but often neglect dynamic interactions within forming tools and presses. This study proposes an approach for achieving accurate real-time prediction of forging outcomes. Initially, a simulation-based surrogate model is developed to replicate key process characteristics related to the billet, enabling prediction of geometry, deformation field, and forging load after an upsetting operation. Subsequently, this model is integrated with a mass-spring-damper model representing the behavior of forging machine and tools. This integration enables the prediction of blow efficiency and energy distribution after each blow, including plastic, elastic, damping, and frictional energy of the upsetting operation. The approach is validated by comparing predictions with experimental results. The coupled model outperformed Finite Element Method (FEM) predictions, exhibiting mean absolute errors (MAE) below 0.1 mm and mean absolute percentage errors (MAPE) below 1% in geometry predictions. Deformation field predictions showed errors below 0.05 mm/mm, and load-displacement curves closely matched experimental data. Blow efficiency predictions aligned well with experimental results, demonstrating a mean absolute error below 1.1%. The observed energy distribution correlated with literature findings, underscoring the model’s fidelity. The proposed methodology presents a promising approach for accurate real-time prediction of forging outcomes. [ABSTRACT FROM AUTHOR]

The inhomogeneity present in the deformation and microstructure during the open die forging of large size ingot significantly influences the mechanical properties of the final part. This study aims to develop a microstructure-based finite element (FE) model and investigate the influence of deformation path on microstructure evolution during the upsetting process of large size ingot of a high strength steel. The difference in deformation path is achieved by modification in anvil shape such as flat, v shape, convex, and concave die. To achieve this goal, hot compression tests were carried out using the Gleeble 3800 thermomechanical simulator. Utilizing the acquired and corrected flow stress data, a material model and a microstructure model were established, and both formulated models were then integrated into the Forge NxT 3.2 finite element simulation software through the inclusion of a dedicated user subroutine. The predictions from the FE analysis were validated with experimental results on standard size hot compression specimens, which allowed for the accurate prediction of the dynamic recrystallized average grain size at the end of hot deformation. Afterwards, the validated FE model was scaled up to simulate the industrial upsetting process, making it possible to investigate the effect of deformation path on inhomogeneity of strain and microstructure evolution at the end of upsetting process for large sized forged ingots. An evaluative analysis of four die geometries, aimed at identifying the optimal die shape for minimizing inhomogeneity in strain and grain size across a large size forged ingot, was conducted. It was found that the convex die provokes the lowest deformation, while the concave die induces the highest deformation values at the center of the ingot. Utilizing the coefficient of variation as an indicator of heterogeneity, it was determined that the v-die and concave die resulted in a more consistent grain size distribution compared to the flat and convex dies. [ABSTRACT FROM AUTHOR]

Forging of sintered Al–Fe–Sn samples was carried out in a closed die at different temperatures. The flow of the material under the influence of frictional forces was non-uniform, and the sample was fractured. It has been established that in order to maintain the integrity of the two-phase material, forging must be carried out with the application of back pressure. It is recommended to forge the composites at elevated temperatures. [ABSTRACT FROM AUTHOR]

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Copyright of BHM Berg- und Hüttenmännische Monatshefte 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.)

The traditional method of manufacturing propellant tanks for rockets and spaceships involves significant amounts of forging, and machining, making it expensive and environmentally unfriendly. A novel approach for manufacturing propellant tanks that reduces the need for machining and friction stir welding processes has been presented in this paper. This approach involves manufacturing a tank half starting from a single metal plate, using innovative and advanced metal forming processes such as hot stretch forming, magnetic pulse forming, hub forming, and integrated stiffened cylinder (ISC) flow forming followed by orbital welding of two tank halves. A life cycle assessment (LCA) study was conducted in accordance with ISO 14044:2006 standard using the ReCiPe 2016 Midpoint (H) method to compare the environmental impacts of the traditional and newly developed approaches for manufacturing propellant tanks. The results of the LCA study showed that the new approach based on advanced forming technologies reduced carbon footprint by 40%, cumulative energy demand by 35%, water footprint by 17%, and materials waste by 4% compared to traditional manufacturing. The lower environmental impact of the new approach was attributed to a decrease in friction stir welding requirements due to the implementation of advanced forming techniques that enable integrated tank production. This lowered the overall energy consumption in the novel approach by a factor of 1.5 and in turn resulted in lower environmental impact compared to traditional forging and machining-based method. Furthermore, a futuristic scenario that involves in-house tank production using the novel approach with minimal transportation of inventories was also simulated. Based on the LCA results, it was seen that the newly developed approach for manufacturing propellant tanks was more environmentally friendly than the traditional approach and its environmental footprint could be further reduced by implementing the futuristic scenario with minimal transportation. This novel approach is also expected to reduce the lead time and production cost of manufacturing a propellant tank. Hence, future efforts in cost assessment and further optimization of raw material and energy usage are recommended. [ABSTRACT FROM AUTHOR]

Forging is a traditional and important manufacturing technology to produce various high strength products and is widely used in engineering fields such as automotive, aerospace and heavy industry. To produce highly accurate product, underfill that the material is not filled into the cavity should strongly avoided. For material saving and near-net product, flash should be minimized. To make the tool life long, it is preferable to produce product with low forging load. It is also preferable to uniformly deform the billet as much as possible for high strength product. Crack is a crucial defect and should strongly be avoided. Therefore, many requirements are taken into account in order to produce the forged product. To meet the requirements, design optimization in forging coupled with computer aided engineering (CAE) is an effective approach. This paper systematically reviews the related papers from the design optimization point of view. For the billet or die shape optimization, the papers are classified into four approaches. The process parameters optimization such as the billet temperature, the die temperature, the stroke length and the friction coefficient is conducted, and the related papers are also classified into four categories. The design variables and the objective function(s) used in the papers are clarified with the design optimization technique. The multi-stage forging including the hammer forging for producing complex product shape is also briefly reviewed. Finally, major performance indexes and the future outlook are summarized for the further development of design optimization in forging. [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.)

Closed-die forging preforms are usually made by open die forging operations, which are subject to significant variabilities. A sensitivity study covering a wide range of influencing parameters has highlighted the predominant influence of the initial billet geometry. The forging die strokes were also highly influential, while their fidelity is sufficient to use them as control parameters in order to compensate the geometrical dispersions of the billet. Consequently, their optimization was performed by taking a nominal preform geometry as the target. Polynomial surrogate models have been constructed to enable real-time optimization. A specific preform was used as a demonstrator in this study, while the approach was generic. The surrogate models were built using data from finite element simulations, which were first validated with an experimental campaign. On the one hand, this approach introduced agility by allowing changes in the billet geometry, and on the other hand, it allowed individual customization of the specific route to each billet. [ABSTRACT FROM AUTHOR]

Tube hydroforging with non-circular shaping has been conducted to show the deformation mechanics of an AHSS tube. In this paper, the tube was hydroforged in a multistage FEA simulation to show the effects of axial forging distance on noncircular cross-sections during hydroforging. The tube will be allowed to expand with a ramped internal pressure, then be shaped to a certain expansion ratio by the axial compression in the forging step and finally be shaped into either a square or an equilateral triangle shaped cross-section. It was observed that triangular shaped models have a greater resistance to thickness loss than the square shaped models. The forging die distance for both square and triangular shaping models each influence the maximum amount of shaping die distance for the process. The simulations show that as the forging die distance increases, the lateral radius increases for both the square and triangular shaped models. For the square shaped models, there is an uncorrelated relationship between the vertical and horizontal longitudinal radii but is correlated in the equilateral triangle configurations. The thickness distributions for the triangular shaped configurations show greater stability in the deformed wall portion than the square shaped configurations. All the model setups failed due to wrinkling, except the triangular shaped model with 20 mm of axial displacement, which failed due to bursting. [ABSTRACT FROM AUTHOR]

Nowadays, cold forging is one of the most commonly utilised methods in industrial manufacturing, and most metal-forming lubricants are not ecologically friendly; in some cases, these chemicals may produce large chemical emissions and pose a risk to the community. Bio-oil lubricants have garnered increasing attention as potential alternatives for mineral oil-based lubricants, since they are critical in resolving existing obstacles. This article intends as a case study and demonstrating the usage of different derivatives of palm oil as a bio-lubricant in the closed forging test (CFT). As an outcome of the friction, wear behaviour and deformation, the closed forging test is important in the knowledge of materials and engineering studies. In this test, aluminium (A1100) was utilised to compare the formation of the workpiece using palm oil based and commercial metal-forming oil as a benchmark lubricant. During the forging process, these components' material flow patterns are analysed at intermediate phases of the die stroke level. Using the experimental data, the finite element approach will be used to predict the workpiece friction, effective stress and metal flow. By developing a Coulomb–Tresca friction model, a cold forging test also was used to do studies on the interaction between the Coulomb friction coefficient (CFC) and Tresca shear friction (TSF). From the results, certain types of palm oil-based lubricants perform better than mineral oil-based lubricants in terms of friction coefficient, with palm stearin having the lowest friction coefficient (m = 0.33/µ = 0.139), followed by palm kernel oil and palm mid olein (m = 0.39/µ = 0.159). The palm oil-based lubricant, on the other hand, has generated poor performance in terms of surface texture and surface roughness (Ra) with a high rate of wear compared to the no sample lubricant and commercial metal-forming oil (m = 0.42/µ = 0.1675). [ABSTRACT FROM AUTHOR]

A technique for simplified simulation of the forging of large ingots using modern machine-learning methods for constructing models that describe stages of thermomechanical processing is described. [ABSTRACT FROM AUTHOR]

The results of the analysis of the influence of temperature–speed deformation parameters and the shape of the billet on the structure and properties of stamped forgings with a complex configuration from titanium alloy OT4-1 are discussed. The influence of deformation on phase transformation processes and the rate of fatigue crack growth (FCGR) in the material of forgings and finished parts is thoroughly investigated. [ABSTRACT FROM AUTHOR]

Work-related illnesses and the resulting employee absences can have a major impact on productivity and competitiveness, especially in small and medium-sized enterprises. Particularly in the forging industry, the manual handling of forged parts leads to high physical stress and thus to frequent illnesses of the musculoskeletal system, especially of the hand-arm system. One possibility to counteract this circumstance is the use of ergonomic forging tongs. In the study presented here, the influence of ergonomic forging tongs on the physical stress of forging employees was investigated by simulation and experiment and compared to conventional forging tongs. Within the simulation and the experimental investigation, forging parts and forging tongs were varied. In the simulation, an ergonomics assessment of the forging situation could be evaluated using the Ergonomic Assessment Worksheet. In the experimental study, gripping force measurements and calorie measurements were used to determine the impact of handling the forging tongs on the forging employees. The results show that the use of the new ergonomically optimized forging tongs can lead to a significant physical relief for the forging employees. The knowledge gained from the ergonomically developed concepts can also be transferred in other industries. [ABSTRACT FROM AUTHOR]

The results of the study of the influence of multi-axial isothermal forging on the microstructure and martensitic transformation in a Ni58Mn18Ga24 alloy have been presented. Forging is performed in two stages: the first stage is forging at 700°C by four passes with true strain e ≈ 1.64; the second stage is forging at 500°C by one pass with e ≈ 0.24. The forging deformation results in the transformation of the original equiaxed-grain structure. No new grains are formed after the first stage of treatment. New recrystallized grains in a very negligible extent begin to be observed only after the second stage of deformation. Probably, at the first stage, the mechanism of fragmentation of the grain structure is not started due to an insufficient density of defects upon the deformation at 700°C. The characteristic temperatures of martensitic transformation are shifted after forging to the low temperature region. The anharmonic change in the sample length is observed in the region of martensitic transformation for the both treated states. In general, this indicates a low level of defect density and internal stresses in the sample. [ABSTRACT FROM AUTHOR]

Forgings are produced in several process steps, the so-called forging sequence. The design of efficient forging sequences is a very complex and iterative development process. In order to automate this process and to reduce the development time, a method is presented here, which automatically generates multi-stage forging sequences for different forging geometries on the basis of the component geometry (STL file). The method was developed for closed die forging. The individual modules of this forging sequence design method (FSD method) as well as the functioning of the algorithm for the generation of the intermediate forms are presented. The method is applied to different forgings with different geometrical characteristics. The generated forging sequences are checked with FE simulations for the quality criteria form filling and freedom from folds. The simulation results show that the developed FSD method provides good approximate solutions for an initial design of forging sequences for closed die forging in a short time. [ABSTRACT FROM AUTHOR]

The specific features of a copper–nickel MN45-VP constantan alloy of vacuum melting are taken into account to reveal the possible causes of the appearance of characteristic hillocks on metallographic sections of its rods as a kind of surface whisker effect. The formation of hillocks is shown to be a consequence of diffusion processes induced by a high chemical heterogeneity of the material. This heterogeneity is found to be related to the absence of special electromagnetic devices in an induction melting furnace for mixing the melt, the components of which are separated in magnetic susceptibility. In other words, the time of holding the melt during cooling-down in the course of degassing is too short. [ABSTRACT FROM AUTHOR]

This investigation reports the influence of vol.% and size (micrometric/nanometric) of the reinforcement particles on machinability of near-full-density (> 99% relative density) powder-forged Al-7075/Y2O3 composites. The composites were processed with 0.1-3. vol% nanometric and 1-10 vol.% micrometric reinforcement and studied in artificially aged (T6) and solutionized conditions. Drilling was performed without applying cutting fluid at 140 rpm rotational speed and 0.12 mm/rev feed rate to produce through holes. Cutting force components (Ft and Fc) and machined surface roughness (Ra) were considered as machinability criteria. The results showed that the reinforcements influence Ft and Fc in both conditions correspondingly as they cause structural alterations and affect composites' hardness. Nevertheless, the reinforcements' effects in T6 were not as prominent as in solutionized condition. In the former condition, the hardness of the alloy matrix due to the formation of precipitates overrides the hardness due to structural alterations caused by reinforcements. Pull-out of secondary reinforcement particles was observed while machining. Besides the composites' hardness, abrasion of the pulled-out reinforcement particles and stuck-up debris of the broken chips on the freshly machined surface governs its roughness. Only a few earlier studies have opted for Y2O3 reinforcement and processed Al-7075/Y2O3 composites by powder forging. Further, machining of Al-7075/Y2O3 composites in solutionized and T6 conditions has been scarcely investigated, and their machinability has been hardly ever analyzed with respect to reinforcement parameters, size, and vol.%. [ABSTRACT FROM AUTHOR]

Wear and fracture of steel dies employed in hot forging were evaluated through metallographic study with the aim of qualifying a Finite Element Simulation of the productive process. Apart from providing useful insights into the causes of die damaging, the simulation was exploited in a Design of Experiments to prevent fracture and to counter different mechanisms of wear. The objective is the optimization of die life acting only on process parameters that are directly adjustable in the actual industrial process. In the examination of stress distribution on the dies and the estimation of die wear, the complete forging cycle has been taken into consideration. Despite the considerable variability of the process, the study demonstrates that it is possible to prevent fracture insurgence and to increase the life expectancy of the die by a careful tuning of standard process parameters. Possible stakeholders of the study are not only process designers but also production managers, as most process parameters are modifiable during production. [ABSTRACT FROM AUTHOR]

This research studies the hot deformation behavior of cast and extruded AZ80 magnesium alloys for forging applications. Uniaxial hot compression tests were carried out at a temperature of 400 °C and strain rates ranging from 0.001 to 0.1 s−1, to various strain levels up to a true strain of 1. Detailed microstructure and texture characterizations of the deformed samples were performed using electron backscatter diffraction and x-ray diffraction techniques. The results show that multiple dynamic recrystallization (DRX) mechanisms were simultaneously active in both starting materials at all the tested deformation conditions, resulting in significant grain refinement. Cast and extruded samples showed the development of a similar microstructure, texture, and flow stress by a strain of 1, despite having very different starting microstructures. This was investigated by considering differences in DRX mechanisms and kinetics, and relative deformation mode activities. Since industrial forgings typically involve strains much higher than 1, comparable final microstructure and texture are expected in industrial-scale forgings of AZ80 at 400 °C, irrespective of the starting material state. [ABSTRACT FROM AUTHOR]

Abstract—To meet the customer's requirements, we developed criteria for sufficient stability of the production of R4 crankshaft forgings with unprocessed counterweights in order to control the scatter of the disbalance depending on the key forging parameters (KFPs) and the hot forging parameters. A method has been developed for predicting the stability of hot forging of R4 crankshaft forgings with unprocessed counterweights using a nonlinear model describing the key characteristic of forging, namely, "curvature." The method of controlling the scatter of the disbalance of a forging depending on its KFPs has been tested in under forging conditions. A methodological database is developed for digital analysis and prediction of the balancing of forgings. [ABSTRACT FROM AUTHOR]

Copyright of BHM Berg- und Hüttenmännische Monatshefte 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.)

A new method of upsetting the workpieces with conical ledges has been proposed and investigated in the paper. A workpiece's relative height before upsetting was H/D = 3.0. Stress–strain state (SSS) has been investigated to determine the level and sign of the compressive stresses in the workpiece. Moreover, the parameter of the stress state in the place location of the axial defects has been evaluated. The degree of axial defect closing and a convexity value has been determined. These parameters have been determined for different dimensions of diameters and heights. It has been established that an upsetting workpiece with conical ledges leads to a uniform strain distribution into the workpiece body. During upsetting on the lateral surface and in the axial zone, there are compressive stresses due to the appearance of a concave workpiece shape. Moreover, there is a decreasing dimension of the axial defects and convexity lateral surface. Effective workpiece geometrical parameters have been determined. Relative diameter (d/D) and height (h/D) of the ledges should be equal from 0.5 to 0.7 and from 0.4 to 0.6, respectively. Recommended degree of upsetting is 50%. Determined recommendations have been verified experimentally during forging ingot with 66,500 kg weight. Obtained experimental data confirmed the results of finite element method (FEM) modeling. The investigation results have been implemented in the industry. [ABSTRACT FROM AUTHOR]

Open-die forging is used to manufacture heavy durable parts such as shafts. In-process measurements are required for shape correction. The passive 3D measurement method is based on forging silhouettes in images and has demonstrated its advantages in this application. However, when using two cameras, only four tangents are available to determine the cross-section. In this paper, we propose a novel multi-camera multi-observation method for forging measurements; it increases the number of tangent lines used to determine the forging cross-section. The results suggest a decrease in measurement error proportional to the square root of the observation number. The six-observation precision is ± 0.5 mm in a measurement volume of 6 × 6 × 2 m for axis straightness and diameter measurements (95% confidence interval). However, many outliers remain in case of diameter measurement. In addition, the forging circularity can be measured. The proposed system shows good agreement with the laser scanning measurement method. Overall, the system has considerable potential for forging manufacturing applications. [ABSTRACT FROM AUTHOR]

The control forging and cooling experiments of H13 and Cr8 die steel were carried out on a MMS-200 thermal simulator. When the cumulative strain of H13 steel reached 2.302 by drawing once, the number of recrystallized grains increased, the recrystallized grains were refined and the corresponding grain grade was about eight. The grain was refined with deformation bands at 750 °C in non-recrystallization region. With increasing cooling rate, the distorted austenite grains evolved into fine recrystallized grains and distorted austenite grains. The microhardness value of annealed H13 steel increased and then decreased with increasing cumulative strain and cooling rate, decreased and then increased with increasing drawing temperature. When the cumulative strain was 1.609 by drawing twice for Cr8 steel, the distribution and quantity of carbide particles were improved. With increasing deformation temperature, the size and number of carbide particles decreased and the dissolution degree increased significantly. Moreover, the intragranular carbide particles dissolved preferentially into matrix. With increasing cooling rate, it presented acicular martensite with granular carbides. The microhardness value of Cr8 decreased first and then increased with increasing cumulative strain and cooling rate, and increased and then decreased with increasing drawing temperature. [ABSTRACT FROM AUTHOR]

Manufacturing titanium aluminides (TiAls) parts are challenging due to their low ductility and fracture toughness. However, processing these materials is of significant interest for applications in high-temperature environments such as the aerospace and automotive industries. Traditional production methods such as casting and forging have been prominent in TiAl manufacturing. Currently, direct energy deposition (DED), electron beam additive manufacturing (EBAM), and laser powder bed fusion (L-PBF) additive manufacturing processes are being considered promising technologies for manufacturing TiAl parts. Recent results suggest the potential for these AM methods to be used for the industrial processing of TiAls. This article reviews the different processing methods for TiAls, highlighting the advantages and progress in using additive manufacturing (AM) technologies. Process characteristics, processing challenges and their causes, and potential mitigation strategies are discussed for each AM method considered. The process-structure–property (PSP) relationships are reviewed, highlighting the optimum process parameters and related mechanical properties. In addition, L-PBF is emphasized as a prospective solution for manufacturing different TiAl alloys. Prospects and recommendations for future studies are also suggested. [ABSTRACT FROM AUTHOR]

Herein, Al-Si-Cu aluminum alloy was prepared and the effect of forging on the microstructure and mechanical properties of novel Al-9Si-5Cu-0.2Zr-0.1Sr-0.16Ti-0.1Ce cast aluminum alloy was investigated. The microstructure analyses show that after forging, the casting defects disappeared, and the irregular Si-eutectic was spheroidized and randomly distributed. The coarse intermetallic compounds (IMCs) gradually dissolved during the solution treatment, and the increased supersaturation of the matrix promoted precipitation kinetics, leading to the coexistence of dense fine θ and θ' strengthening phases. Moreover, the dislocation strengthening effect for the forged alloy was enhanced. The mechanical tests show that compared to the as-cast alloy, the mechanical properties of the forged alloy including the hardness, yield strength, tensile strength, and plasticity were improved by optimizing the microstructure. [ABSTRACT FROM AUTHOR]

Engineering design shows a growing interest in exploring cost analysis to anticipate manufacturing issues and integrate production aspects within the product development process. This research aims to highlight key elements (inputs, parameters, models) to accurately predict the cost of a forged part using a complete model, with important information that can be available during the design phase. For this purpose, a systematic literature review of existing engineering methodologies developed for cost analysis of forged parts (i.e., cost estimation, DtC, and ABC) was performed with characterizations of the different approaches for evaluating the most important topics related to this objective. As a result, the most important insights related to the aim of this review are provided: (i) among quantitative methods, analytical and parametric models are the most suitable approaches to develop a cost estimation, (ii) a cost model based on a linear equation supported by single or multiple variables seems to be the most accurate tool to establish a robust cost analysis in the design of forged components, and (iii) input parameters related to the material type and geometrical features are the most critical cost-drivers in the cost assessment. Moreover, this review contributes to identifying emerging applications and obsolete topics, providing the ground to investigate unexplored areas relevant to future research. [ABSTRACT FROM AUTHOR]

A series of ring compression tests using BS970:708M40 alloy steel samples were studied. These tests were conducted using a 2-factor soak-temperature variable, namely 1030 °C and 1300 °C, and a 4-factor lubricant variable consisting of unlubricated samples, synthetic water-based, graphite water-based, and graphite and molybdenum disulphide viscous grease. The lubricant agents were all applied to the tool/billet interface. Process variables such as blow force and heating were controlled with the use of a gravitationally operated drop hammer and an automated programmable induction-heating unit. This matrix of the experimental parameters offered a sound base for exploring dominant factors impacting upon bulk deformation. This deformation was measured using fully calibrated equipment and then systematically recorded. A finite element modelling framework was developed to further improve the thermo-mechanical deformation process understanding, with finite element (FE) predictions validated through experimental measurement. Through the combined experimental and FE work, it was shown that temperature variation in the experimental parameter matrix played a larger role in determining deformation than the lubrication agent. Additionally, the use of synthetic and graphite water-based lubricants does not necessarily produce greater deformation when used in high-temperature forgings due to the lubricants breaking down, evaporating, or inducing rapid billet cooling as a result of the carrier used (water). Graphite-molybdenum disulphate grease far outperforms the other lubricants used in this trial in reducing friction and allowing deformation to occur across a die-face. [ABSTRACT FROM AUTHOR]

Isothermal compression tests are conducted using a thermomechanical simulator at a constant strain rate during deformation temperature range of 850 to 950 °C and strain rate range of 0.001-10 s - 1 to study the flow behavior of Ti17 alloy with initial basketweave microstructure in β forging process. The strain rate sensitivity exponent m and strain hardening exponent n are calculated, and the strain-compensated constitutive model of flow stress using hyperbolic sine-based Arrhenius model is constructed. The results show that the strain rate sensitivity exponent m is greater than 0.3 when the strain rate is low in the range of 0.001-0.01 s - 1 , and reaches its maximum at 900 °C; the component is less than 0.3 at high strain rate range of 0.1-10 s - 1 , and it is slightly lower at 850-900 °C compared with at 920-950 °C. The strain hardening exponent n monotonously decreases with the increase in true strain at strain rate of 0.001 s - 1 , while for strain rate in the range of 0.01-10 s - 1 , it decreases with the increase in strain when the true strain is less than 0.3 but does not show significant change when the true strain is greater than 0.3. The established strain-compensated flow stress constitutive model has high prediction accuracy with average absolute relative error (AARE) of 5.32% and correlation parameter R of 0.993. The model can thus be used to provide theoretical guidance for selecting β forging process parameters, and also provide the basic data for finite element simulation of β forging process of Ti17 alloy. [ABSTRACT FROM AUTHOR]

The purpose of the study is to elucidate fiber deformation behavior during the forging of a spur gear by using a carbon fiber reinforced thermoplastic billet. The billet was composed of PA6/UD chips with a fiber length of 30 mm and fiber volume fraction of 50%. A gear forging mold was developed to deform the billet into a gear shape without cutting the fibers. Three types of billets were prepared: a horizontal billet with fibers orientated in the X and the Y directions, a vertical billet with fibers orientated in the Z and the X directions, and a random billet with fibers randomly orientated in the X–Y plane. The fibers along the tooth profile were formed using the horizontal and vertical billets. The adjacent teeth were connected by the fibers. A maximum tooth bending strength was 500 MPa. The delamination occurred under the tooth valley. The orientation of fibers in the teeth using the random billet was also random. The fracture occurred in the middle of the tooth. The results indicated that the fiber orientation in the billet is strongly correlated to the fiber orientation in the gear teeth and the tooth strength. The fiber orientation in the billet proposed in the study can form a tooth with fibers along its profile and with high strength. [ABSTRACT FROM AUTHOR]

An experimental-numerical methodology was proposed for the parameter identification of constitutive laws, when applied to hot forging. Industrial presses were directly used to generate the reference experiments for identification. The strain and temperature heterogeneity that appears during on-press compression experiments was taken into account by an FE-based inverse method. Specific experiments were designed for the identification of the heat transfer and friction coefficients. A testing tool was designed and instrumented with displacement sensors and a force cell. This was then used on a hydraulic press and a screw press in order to cover a large range of strain rates. The identified parameter set was validated with respect to specialized plastometers, and a semi-industrial validation forging process. A reasonable accuracy was observed, particularly in realistic forging conditions. [ABSTRACT FROM AUTHOR]

The Chengdu Plain was the iron production center in southwest China in the Han dynasty (202 BC-220 AD), which three iron smelting sites and large amounts of iron objects were excavated in the past decades. However, metallurgical studies of iron production in the Chengdu Plain have been overlooked for a long time. This paper provides an opportunity to understand the iron production technology in the Chengdu Plain in the Han dynasty. The metallurgical analyses of excavated iron objects from the Baozishan cemetery site show that most iron tools and weapons were forged from decarburized iron and fined iron. Besides, carburization, decarburization, and quenching techniques were used to control the malleability of iron objects. According to the results, the primary use of iron at Baozishan was forged wrought iron and steel, which evidenced that forging technique played an important role in the Chengdu Plain in the Han dynasty. [ABSTRACT FROM AUTHOR]

The paper presents the analysis of hot deformation behavior of Ti-6Al-2Sn-4Zr-6Mo (Ti-6246) alloy using the theory of dynamic material modeling (DMM) based on hot compression tests performed to a total true strain of 1 at the strain rates from 0.01 to 100 s−1 and at the temperatures within the range between 800 and 1100 °C. The processing maps according to the Prasad's criterion were developed. The analysis of the processing maps allowed for the placement of domains describing the areas of potentially favorable combinations of hot deformation parameters. The microstructure observations of the investigated alloy specimens after hot deformation in stability and instability areas were conducted. The optimal processing parameters for numerical modeling of Ti-6246 alloy forging were selected based on processing maps. After complex analysis of the obtained results, microstructural observations and numerical modeling of forging of selected part, the forging tests of Ti-6246 alloy were realized. The obtained product quality assessment was carried out by computed tomography non-destructive testing. [ABSTRACT FROM AUTHOR]

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Copyright of BHM Berg- und Hüttenmännische Monatshefte 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.)

The austenite grain refinement and homogenization control strategies of the flexspline were investigated, including microalloying with V and Ti, the evolution of austenite grain size and homogenization during forging processes and multiple times of heat treatment. The results show that the grain growth rate during high temperature was lowered obviously which leads to the grain refinement, owing to the addition of microalloying elements V and Ti. After holding at 1200 °C for 40 min, the average grain size of 0.05%V+0.0045%Ti steel was reduced by 39% compared with 0.04%V+0.0025%Ti steel. During the manufacturing process of the flexspline from induction reheating to quenching and tempering, the austenite grain was gradually refined from 340.0-380.7 to 9.3-9.8μm. The grain size and homogenization were improved obviously in the first two times during the multiple times of normalizing. After multiple times of quenching and tempering, the size and homogenization of the grain were gradually improved. The exponential relationship between grain size and multiple times of normalizing and the linear relationship between grain size and multiple times of quenching and tempering were also obtained, respectively. [ABSTRACT FROM AUTHOR]

Graphene has exceptionally high in-plane strength, which makes it ideal for various nanomechanical applications. At the same time, its exceptionally low out-of-plane stiffness makes it also flimsy and hard to handle, rendering out-of-plane structures unstable and difficult to fabricate. Therefore, from an application point of view, a method to stiffen graphene would be highly beneficial. Here we demonstrate that graphene can be significantly stiffened by using a laser writing technique called optical forging. We fabricate suspended graphene membranes and use optical forging to create stable corrugations. Nanoindentation experiments show that the corrugations increase graphene bending stiffness up to 0.8 MeV, five orders of magnitude larger than pristine graphene and corresponding to some 35 layers of bulk graphite. Simulations demonstrate that, in addition to stiffening by micron-scale corrugations, optical forging stiffens graphene also at the nanoscale. This magnitude of stiffening of an atomically thin membrane will open avenues for a plethora of new applications, such as GHz resonators and 3D scaffolds. [ABSTRACT FROM AUTHOR]

Copyright of BHM Berg- und Hüttenmännische Monatshefte 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.)

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.)

Ancient Indian iron artefacts have always fascinated researchers due to their excellent corrosion resistance, but the scientific explanation of this feature remains to be elucidated. We have investigated corrosion resistance of iron manufactured according to traditional metallurgical processes by the Indian tribes called 'Agaria'. Iron samples were recovered from central India (Aamadandh, Korba district, Chhattisgarh). Iron artefacts are investigated using a range of correlative microscopic, spectroscopic, diffraction and tomographic techniques to postulate the hidden mechanisms of superlative corrosion resistance. The importance of manufacturing steps, ingredients involved in Agaria's iron making process, and post-metal treatment using metal-working operation called hot hammering (forging) is highlighted. This study also hypothesizes the probable protective mechanisms of corrosion resistance of iron. Findings are expected to have a broad impact across multiple disciplines such as archaeology, metallurgy and materials science. [ABSTRACT FROM AUTHOR]

In order to reduce the casting defects in the large forgings such as solidification segregation, a new forming technology of the semi-solid liquid core forging is put forward in this paper. We elucidate the effectiveness of the semi-solid liquid core forging by simulating the forging process of the 19 tons flat steel ingot in the commercial software DEFORM-3D. A coupled temperature/stress finite element (FE) model is developed to calculate the temperature, the effective stress, the effective strain, the maximum principal stress and the anvil force. These output variables are compared correspondingly from the semi-solid liquid core forging and the traditional forging after the first pass reduction. The deformation of the semi-solid liquid core forging is more uniform and the equipment capacity is also improved. Compared with the traditional forging, the new forging technology is directly forged at high temperature without reheating for a long time and the energy is saved. [ABSTRACT FROM AUTHOR]

Present study describes the effect of forge application under consideration of friction time on metallurgical and mechanical properties of friction welded joint for AISI 316. Direct drive friction welding (DDFW) has been utilized to obtain welded joints. Three friction times (6.5 s, 8.5 s and 10 s) with two directions for this study were used; the first direction was achieved by forge phase elimination and the second was performed under forge phase application. Macro-microstructure for welded joint, microhardness across the axial direction, tensile tests and tensile fracture morphology were investigated. As a conclusion, flash formation was decreased about 30% without forge compared to forge application. Thermo-mechanically affected zone (TMAZ) was extended in 8 mm at the interface without forge and highly plastically deformed zone (HPDZ) can be found at the interface after forge application. At shorter friction time for the two directions, ultimate tensile strength (UTS) and ductility were revealed closer to AISI 316. Hence, all tensile fractures were occurred adjacent to the interface at TMAZ, except in the shorter friction time after in forge application, the fracture was happened at the base metal, and that was confirmed with the fracture morphology which has the same character of AISI 316. [ABSTRACT FROM AUTHOR]

A small series of ring compression tests were performed on BS970:708M40 alloy steel. The samples were tested using a 2-factor temperature variable, and a 4-factor lubricant variable, as the design parameters. Two differing soak temperatures were used, namely 1030 °C and 1300 °C respectively. The lubricants applied at the billet to tooling interface were synthetic water–based, graphite water–based, graphite and molybdenum disulphide viscous grease, and finally, unlubricated samples were tested. The ring compression tests were performed using a traditional drop forging hammer and induction heating to minimise any unintentional process variability. The impact that the two varying process parameters have upon the compression sample was then assessed by measuring each sample's surface hardness and surface roughness prior to and post forging with fully calibrated equipment. It was demonstrated that the higher soak temperature of 1300 °C yielded a lower surface hardness value and higher surface roughness than the lower soak temperature, 1030 °C. The two water-based lubricants offered negligible change in results compared with the unlubricated forging, strongly suggesting that the lubricants were evaporated off the surface prior to forging. However, the results from the graphite–molybdenum disulphate grease do indicate in particular higher surface roughness than other lubricants, and a non-symmetric distortion pattern. [ABSTRACT FROM AUTHOR]

AA6082 extruded bars were annealed and then hot-deformed at 693 K, cold-deformed at room temperature (RF), or treated at sub-zero temperatures (CF). After the solution and the aging treatment, the mechanical properties of the samples were tested. The experimental results demonstrate that the hot-deformed samples were stronger but less elongated than the RF and CF samples. All hot-deformed (HF), RF, and CF samples had mechanical properties that exceeded UTS > 310, YS > 260 MPa and an elongation > 10%. The RF and CF samples greatly enhance elongation (up to 16%) and toughness in addition to moderate strength (UTS ≥ 320 and YS ≥ 295 MPa). Affected by having high fractions of high misorientation angle grain boundaries (MAGBs) per unit area in the matrix, the RF and CF samples deteriorated their corrosion resistance by degrading Ecorr values. The surface of corroded HF50 was recorded to confirm that the particles were attacked by chloride and oxidized. Increasing the total lengths of high-MAGBs and particle counts per unit area accelerated corrosion to lift up Icorr values. [ABSTRACT FROM AUTHOR]

In this study, the performances of the WC tools coated with TiCN and AlCrN by filter cathodic arc in hole drilling of forging brass were investigated and compared with that of uncoated one. The performances were evaluated using the exit burr height (EBH) criterion and process capability indices as a function of number of parts drilled with the three types of drills. The results showed that there were significant differences of EBH and the process capability index of Cpm during drilling of the workpieces with the three types of drills. The desired EBH values of 0.152-0.1535 mm, roughness values of 2-3 µm and drilled diameters of 17.79-17.8 mm were achieved with the appropriate operating conditions including cutting speeds and feed rates ranging from 0.17 to 0.19 mm/rev and 55 to 57 m/min, respectively. [ABSTRACT FROM AUTHOR]

β-Texture evolution during cooling after forging in the β single-phase region and (α + β) dual-phase region was investigated in Ti-6Al-2Sn-4Zr-6Mo alloy. Typical {001} and {111} β fiber textures of the β phase developed during forging. Dynamic-recrystallized β grains formed and inherited the orientation of their parent grains during forging in the β single-phase region. The {001} texture was enhanced with decreasing cooling rate after forging in the β region, that is, as cooling time in the β region increased. The results of the post-forging holding in the β region demonstrated that the recrystallized grains that grew in the β region consumed the adjacent {111}-oriented parent grains and initially enhanced the {001} texture. However, the enhancement of the {001} texture was moderated with increasing holding time because of the increased orientation deviation between the recrystallized grains and the parent grains. In addition, the {001} β texture was weakened by the growth of static-recrystallized grains after its incubation period during the holding time. These results indicate that growth of dynamic-recrystallized and static-recrystallized grains moderated the increase of the {001} texture intensity at low cooling rates of specimens forged in the β region. In specimens forged near the β-transus temperature and in the (α + β) dual-phase region, the {001} texture intensity was only slightly affected by the cooling rate. Recrystallization of the β phase was suppressed by the precipitation of the α phase during forging and cooling at low temperatures. A slow cooling rate of − 2 °C/s was determined by measuring the temperature change of a large specimen similar in size to those used in real-world applications. [ABSTRACT FROM AUTHOR]

In this paper, the microstructures and mechanical properties (i.e., impact, tensile and hardness) of four different hypoeutectic Al–Si cast alloys were studied before and after forging process. The effect of adding various grain refiners and grain modifiers on the properties were also studied. Results indicated that, in combination with grain refiner and modifier, the hypoeutectic Al–Si cast alloys have microstructures consisting of uniformly distributed α-Al dendrites, inter-dendritic network of fine eutectic silicon and fine precipitation of CuAl2 particles in the inter-dendritic area after 50% reduction in forging. The combined addition of grain refiner and modifier to the alloy demonstrated improved mechanical properties in as-cast condition as opposed to those alloyed with individual grain refiner or modifier. The improved mechanical properties of hypoeutectic Al–Si cast alloys were linked to reduced primary dendrites, uniform distribution of eutectic silicon and inter-dendritic precipitation of small CuAl2 particles after forging. [ABSTRACT FROM AUTHOR]

The isothermal compression tests of C71500 copper-nickel alloy at different temperatures (1 073–1 273 K) and strain rates (0.01–10 s−1) were carried out on Gleeble-3500 thermo-mechanical simulator. The real stress-strain data were obtained. On the basis of dynamic material model, the power dissipation was established. The peak efficiency of the power dissipation is 57%. At the same time, Prasad's, Murty's and Babu's instability criteria based on Ziegler's expectant rheology theory, and Gegel's and Malas's instability criteria based on Lyaponov's function theory, were used to predict the unstable regions in the processing map. The maximum entropy generation rate and large plastic deformation principle are more in line with the hot deformation process of C71500 alloy, so the accuracy of Prasad's instability criterion is much better. According to the obtained macro-crack and micro-metallographic structure morphologies, the temperature range of 1 098–1 156 K and the strain rate range of 2.91–10 s−1, and the temperature range of 1 171–1 273 K and the strain rate range of 0.01–0.33 s−1 are more suitable for the processing area of C71500 alloy. The accuracy of the above conclusions were verified by the forging of materials and the analysis of hot piercing tubes. The significance of this paper is to provide theoretical basis and technological conditions for hot-press processing of C71500 alloy. [ABSTRACT FROM AUTHOR]