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Annealed austenitic stainless steel AISI 316L sheets of 1.6-mm and 2-mm thickness respectively was successfully joined by cold metal transfer (CMT) process at two different heat inputs of 0.125 to 0.236 kJ/mm. The process parameters such as welding current and welding speed were optimized to get defect free joints with full penetration depth. The geometry of the weld bead and microstructure of AISI 316L tailor welded blanks using ER308L filler wire are evaluated. Weld metal microstructure inspection by optical microscopy (OM) revealed that higher heat input used to melt the material led to equiaxed grains in the center of weld metal (WM). Due to the lower heat input, the microstructure at the heat-affected zone (HAZ) was similar to base metal (BM). Tailor welded blank's (TWBs) were formed by designing L9 orthogonal array for 1.6 mm, 2 mm, and dissimilar thickness joint (1.6 mm and 2 mm) wherein the joints exhibited higher tensile strength and hardness as compared to base metal. The increase in tensile strength is corroborated to the increase in δ-ferrite and content of the alloying elements and the grain size in the WM. The microstructure refinement and the δ-ferrite presence contributed to the increase in hardness at the WM compared to HAZ and BM. Bend test revealed quality and soundness of the TWBs with no cracks or openings. The X-ray diffraction plots exhibited an increase in ferrite in WM and the ferrite number has been quantified at an average of 6.36 FN for TWBs and less than 0.5 FN for BM using Fischer Feritscope, which results in better mechanical properties. Fractography examinations indicated that samples failed as a result of the presence of dimples and microvoids resulting in ductile mode fracture at the welded joints. [ABSTRACT FROM AUTHOR]

• Dependency of the defect tolerance on the building direction of AISI 316L. • High impact of microstructural porosity on the fatigue behavior of SLM-material. • Impact of building direction on defect tolerance could be determined with PhyBaL CHT. • Accordance of the results of PhyBaL CHT and √area-concept. • Correlation of constant amplitude tests with the results of short-time procedures. To exploit the high potential of additive manufacturing (AM) technology for production of safety relevant structural components, it is indispensable to get a sound knowledge about the fatigue behavior of additively manufactured materials. However, fatigue investigations are time and material consuming, leading to high costs for fatigue validation of AM materials. To reduce this effort, in this research work the short-time procedures PhyBaL CHT (CHT: cyclic hardness test), based on cyclic indentation testing, and PhyBaL LIT (physically based lifetime calculation; LIT: load increase test), based on load increase tests (LITs) are used to comprehensively characterize the fatigue behavior of selectively laser melted specimens made of austenitic stainless steel AISI 316L in three different building directions. The different building directions lead to layer planes perpendicular (SLM-V), in 45° direction (SLM-45) and parallel (SLM-H) to the loading direction. In addition to the short-time procedures, several constant amplitude tests (CATs) were performed to validate the results. The results of CATs showed only slight differences in the fatigue behavior of SLM specimens, which correlates well with the results of LITs. Furthermore, the results of CATs demonstrate a high influence of the microstructural defects i.e. pores on the fatigue behavior and different defect tolerances depending on the building direction. The vertical building direction lead to the highest defect tolerance, which is proved by the results of PhyBaL CHT. The S-N f curves, calculated by the PhyBaL LIT approach, are in good accordance to the CATs and hence, can describe the characteristics of the fatigue properties of the different orientations with good accuracy. Consequently, the influence of different building directions on the fatigue behavior of the SLM specimens could be determined efficiently with the presented short-time procedures. [ABSTRACT FROM AUTHOR]

The aim of this research is to investigate the microstructural changes and work hardening behavior of AISI 316L 0.5-mm-thick sheet due to micro-plasma arc welding. AISI 316L similar sheets were welded in single-pass square butt joint configuration. The microstructure in the fusion zone typically contains a variety of complex δ-ferrite-austenitic structure, which significantly increased hardness value compared to the base material because of rapid solidification of the weld pool. Systematic tensile test was performed to investigate strain rate sensitivity of the welded joint under quasi-static loading conditions. The multistage work hardening behavior was determined by Kocks–Mecking (K–M) model and differential Crussard–Jaoul analysis. In both the cases, stage III work hardening behavior and stage IV work hardening behavior were observed. The stress–strain curves of welded specimen at different strain rates were analyzed in terms of Hollomon, Ludwik and Swift equations to determine work hardening exponent values. The welded joints were ruptured in the transition zone of heat affected and fusion zones. The fractographic observation exhibited variation in dimple and void density over strain rate from 0.0001 to 0.0015 s−1. [ABSTRACT FROM AUTHOR]

In this study, AISI 316L / AISI 4140 steel couple was welded by a continuous drive friction welding machine under constant friction and forging time with three diffirent rotational speeds, forging pressure and friction pressures respectively. SEM microscopy was implemented to determine the metallurgical changes in the region of interface regarding the rotational speed, friction and forging pressure. In addition, microhardness distribution across the interface was evaluated considering the metallurgical changes. From microstructure examinations and microhardness results, the welds which were realized under lower rotational speeds, forging pressures and friction pressures it was seen that there were unconnected regions and some defects in microstructural interface and moreover microhardness values were obtained too lower when compared to the other higher parameters. However, concerning with increasing rotational speeds, heat affected zone (HAZ) was extended and also microhardness value was considerably increased with transforming martenzite phase and resulting work hardening in the excessively deformed region. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract A wide proportion of the industrial Selective Laser Melting (SLM) systems are operated with high brilliance fiber laser sources. These sources are most commonly operated in continuous wave (CW). A smaller fraction of these systems employs pulsed wave (PW) emission by power modulation, resulting in pulses with μs level durations, kHz level repetition rates and comparable peak powers to CW emission. Clearly, the laser temporal emission mode can have an impact over temperature fields, which in return control the melt pool size, stability and densification behaviour. The aim of this paper is to investigate the effect of laser emission regime on the melting efficiency in SLM. In particular, an analytical model was developed to investigate the process efficiency in single track formation at fixed energy input when employing different emission modes. A single mode fiber laser installed on an in-house developed prototype powder bed fusion system was used as the experimental setup with AISI 316 L metallic powders. The effect of duty cycle was evaluated starting from CW (i.e. 100% duty) moving towards PW, at fixed energy density levels. Results show that at constant energetic input, CW increases process melting efficiency up to 3 times whilst the deposition stability is reduced with lower duty in PW regime. Although less efficient, at stable conditions the use of modulated emission produces narrower tracks providing higher process resolution. [ABSTRACT FROM AUTHOR]

Samples of 316L stainless steel were subjected to severe plastic deformation by the groove pressing technique at room temperature to a maximum equivalent deformation of ε ~ 4,64. Subsequently, the mechanical properties were evaluated and related to the microstructure by the scanning electron microscopy technique. The results show that after the first step an increase in the hardness, the elastic limit and the ultimate tensile strength in the material is obtained, due to the reduction of the grain size, the presence of mechanical twinning and martensite induced by deformation. [ABSTRACT FROM AUTHOR]

The new ceramic tools, intended for the machining of thermo resistant materials, can be a viable option for the machining of austenitic stainless steels. The present work aims to show the results of the behavior from the wear point of view, of a ceramic tool BIDEMICS, during the machining in dry and using Minimum Quantity of Lubricant (MQL), of the steel AISI 316L. An experiment based on a dry turning operation with MQL of a bar of 25 mm in diameter was developed, varying the cutting speed in three levels, 200 m/min, 300 m/min and 400 m/min and the advance in three levels 0,1 mm/rev, 0,15 mm/rev and 0,2 mm/rev. In the study, the wear behavior of this tool was evaluated and the models that describe the initial wear rate were determined. [ABSTRACT FROM AUTHOR]

This paper deals with an experimental analysis of stress prediction and simulation prior to 3D printing via the selective laser melting (SLM) method and the subsequent separation of a printed sample from a base plate in two software programs, ANSYS Addictive Suite and MSC Simufact Additive. Practical verification of the simulation was performed on a 3Dprinted topologically optimized part made of AISI 316L stainless steel. This paper presents a typical workflow for working with metallic 3D printing technology and the state-of-the-art knowledge in the field of stress analysis and simulation of printed components. The paper emphasizes the role of simulation software for additive production and reflects on their weaknesses and strengths as well, with regard to their use not only in science and research but also in practice.

Nowadays Additive Manufacturing (AM) is catching on and spreading across various fields at an astonishing rate. High energy physics, where materials are often exposed to special environmental conditions, is also starting to use this technology. The aim of this paper is to compare traditional and 3D printed stainless steel AISI 316L products with an eye turned to the specific high energy applications environment. The manufactured samples are subjected to different heat treatments, including vacuum firing, as this thermal treatment is usually adopted for ultra-vacuum applications and cryogenic. Experimental tests are carried out on a set of samples to analyse the material composition and to assess properties such as mechanical performance in cryogenic application, high magnetic fields and ultra-vacuum compatibility. Such analysis of the material behaviour allows weakness and strength of the technology to be identified, compared to traditional AISI 316L. [ABSTRACT FROM AUTHOR]

To understand the effect of surface machining on the resistance of AISI 316L to SCC (stress–corrosion cracking) in marine environments, we tested nuts surface-machined by different methods in a seawater-spraying chamber. Two forms of cracks were observed: on the machined surface and underneath it. On the surface, cracks connected with the pitting sites were observed to propagate perpendicular to the hoop-stress direction, identifying them as stress–corrosion cracks. Under the surface, catastrophic transgranular cracks developed, likely driven by hydrogen embrittlement caused by the chloride-concentrating level of humidity in the testing environment. Under constant testing conditions, significantly different SCC resistance was observed depending on how the nuts had been machined. Statistical evaluation of the nut surface-crack density indicates that machining by a “form” tool yields a crack density one order of magnitude lower than machining by a “single-point” tool. Microstructural analysis of form-tool-machined nuts revealed a homogeneous deformed subsurface zone with nanosized grains, leading to enhanced surface hardness. Apparently, the reduced grain size and/or the associated mechanical hardening improve resistance to SCC. The nanograin subsurface zone was not observed on nuts machined by a single-point tool. Surface roughness measurements indicate that single-point-tool-machined nuts have a rougher surface than form-tool machined nuts. Apparently, surface roughness reduces SCC resistance by increasing the susceptibility to etch attack in Cl--rich solutions. The results of X-ray diffractometry and transmission electron microscopy diffractometry indicate that machining with either tool generates a small volume fraction (< 0.01) of strain-induced martensite. However, considering the small volume fraction and absence of martensite in regions of cracking, martensite is not primarily responsible for SCC in marine environments.

Rapid cooling rates and steep temperature gradients are characteristic of additively manufactured parts and important factors for the residual stress formation. This study examined the influence of heat accumulation on the distribution of residual stress in two prisms produced by Laser Powder Bed Fusion (LPBF) of austenitic stainless steel 316L. The layers of the prisms were exposed using two different border fill scan strategies: one scanned from the centre to the perimeter and the other from the perimeter to the centre. The goal was to reveal the effect of different heat inputs on samples featuring the same solidification shrinkage. Residual stress was characterised in one plane perpendicular to the building direction at the mid height using Neutron and Lab X-ray diffraction. Thermography data obtained during the build process were analysed in order to correlate the cooling rates and apparent surface temperatures with the residual stress results. Optical microscopy and micro computed tomography were used to correlate defect populations with the residual stress distribution. The two scanning strategies led to residual stress distributions that were typical for additively manufactured components: compressive stresses in the bulk and tensile stresses at the surface. However, due to the different heat accumulation, the maximum residual stress levels differed. We concluded that solidification shrinkage plays a major role in determining the shape of the residual stress distribution, while the temperature gradient mechanism appears to determine the magnitude of peak residual stresses.

Directed energy deposition (DED) as a metal additive manufacturing technology can be used to produce or repair complex shape parts in a layer-wise process using powder or wire. Thanks to its advantages in the fabrication of net-shape and functionally graded components, DED could attract significant interest in the production of high-value parts for different engineering applications. Nevertheless, the industrialization of this technology remains challenging, mainly because of the lack of knowledge regarding the microstructure and mechanical characteristics of as-built parts, as well as the trustworthiness/durability of engineering parts produced by the DED process. Hence, this paper reviews the published data about the microstructure and mechanical performance of DED AISI 316L stainless steel. The data show that building conditions play key roles in the determination of the microstructure and mechanical characteristics of the final components produced via DED. Moreover, this review article sheds light on the major advancements and challenges in the production of AISI 316L parts by the DED process. In addition, it is found that in spite of different investigations carried out on the optimization of process parameters, further research efforts into the production of AISI 316L components via DED technology is required.

Present study describes results of research conducted on sinters manufactured from a powdered AISI 316L austenitic stainless steel modified with an addition of boron-rich master alloy. The main aim was to study impact of the master alloy addition on a corrosion resistance of sinters in 0.5M water solution of NaCl. In order to achieve it, a potentiodynamic method was used. Corrosion tests results were also supplemented with a microstructures of near-surface areas. Scanning electron microscope pictures of a corroded surfaces previously exposed to the corrosive environment were taken and compared. It was successful to increase the corrosion resistance of AISI 316L sinters modified with master alloy. It was also successful in particular samples to obtain a densified superficial layer not only on the sinters sintered in the hydrogen but also on sinters sintered in the vacuum. No linear correlation between presence of the densified superficial layer and the enhanced corrosion resistance was noticed.

Abstract Lattice structures as new design concepts have been considered to manufacture a Stirling engine regenerator by SLM. Two unit-cell topologies have been selected, cubic and rhombic, and different strut dimensions have been designed in order to achieve a porosity of 70% approximately. As a baseline, a regenerator based on a volumetric woven wire mesh with similar porosity properties has been taken into account. Computational fluids dynamics have been employed to analyze heat transfer and pressure drop characteristics. In addition, these properties have been obtained experimentally for demonstrators built with the defined cellular lattice structures. [ABSTRACT FROM AUTHOR]

Copyright of Matériaux et Techniques is the property of EDP Sciences 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.)

In this study, AISI 316L / AISI 4140 steel couple was welded by a continuous drive friction welding machine under constant friction and forging time with three diffirent rotational speeds, forging pressure and friction pressures respectively. SEM microscopy was implemented to determine the metallurgical changes in the region of interface regarding the rotational speed, friction and forging pressure. In addition, microhardness distribution across the interface was evaluated considering the metallurgical changes. From microstructure examinations and microhardness results, the welds which were realized under lower rotational speeds, forging pressures and friction pressures it was seen that there were unconnected regions and some defects in microstructural interface and moreover microhardness values were obtained too lower when compared to the other higher parameters. However, concerning with increasing rotational speeds, heat affected zone (HAZ) was extended and also microhardness value was considerably increased with transforming martenzite phase and resulting work hardening in the excessively deformed region. [ABSTRACT FROM AUTHOR]

The sinter-bonding method was used to produce AISI 316L/17-4 PH components by conventional powder metallurgy technology. The production process consisted of following steps: the powder layering, co-pressing and co-sintering processes. The co-sintering process was carried out at different sintering temperatures (1200, 1250 and 1300 °C), and times (60, 90 and 120 min) in hydrogen atmosphere. The effect of co-pressing and co-sintering conditions on the ability to create a permanent connection between AISI 316L and 17-4 PH stainless steels was investigated. The densification, dimensional change and microstructural evolution of sintered AISI 316L/17-4 PH components were studied. The increase in co-pressing pressure as well as using of the longer time and the higher temperature of co-sintering process contributed to increase in AISI 316L/17-4 PH component density. The dilatometric study as well as dimensional changes measurements revealed an appropriate sintering compatibility for AISI 316L and 17-4PH steels when the sintering process was carried out at the temperature of 1200 °C for time ranging from 60 to 120 min and at 1250 °C for shorter sintering times. The sintering at temperature of 1300 °C (regardless of other manufacturing conditions) led to a significant deviation from the cylindrical shape of samples, as a result of difference of shrinkage of AISI 316L and 17-4 PH steels. Microstructural study indicated that AISI 316L and 17-4 PH steels creates a good diffusion joint (without any cracks and warpage) during the high-temperature sintering process. Nickel diffusion takes place from the AISI 316L to 17-4 PH stainless steel, and copper and molybdenum diffuse in opposite direction of nickel diffusion. It is possible to achieve a solid connection between two materials exhibiting difference in chemical composition by using sinter-bonding and conventional powder metallurgy technology. [ABSTRACT FROM AUTHOR]

Casting metal products are characterized by undesired void defects due to the shrinkage occurring during the solidification of molten material. In order to deliver safe and sound components satisfying the customer requirements, these defects need to be reduced or if possible eliminated. Hot metal forming processes can be used for this purpose therefore, the calibration of their parameters is a fundamental task. In this paper a study of the void closure during hot rolling of 316L stainless steel slabs coming from continuous casting has been conducted. The effects of the hot rolling main parameters (i.e. percentage of reduction, cooling time, and side of reduction) on void closure index have been investigated by means of FE analysis. Data coming from experimental tests performed by Cogne Acciai Speciali S.p.a. were utilised to validate the model and the research results. A correlation between void closure indexes and the residual voids along the hot rolled slabs axis was found for AISI 316L stainless steel. Moreover, new geometric indexes depending on the rolling parameters were defined. Also in this case a correlation between these new indexes and the void closure was found. [ABSTRACT FROM AUTHOR]

The objective of the paper is to study the mechanical behaviour of two welded joints that differ in their filler metals in regards with the microstructure. Gas tungsten arc welding process was employed to perform the welded joints between AISI 316L as a base metal and either ER316LN or ER308LN as filler metal. For both the welded joints, the microstructure of the fusion zone was predominantly austenitic containing a small amount of residual dendritic δ-ferrite in skeletal morphology formed during solidification (FA mode) and whose transformation to austenite upon cooling was incomplete. However, XRD analysis pointed out a relatively higher amount of δ-ferrite in the fusion zone of the welded joint (316L/ER308LN) than that in the welded joint (316L/ER316LN), as it could be expected from the calculated (Creq/Nieq) ratio of Schaeffler formula. The composite microstructure of the fusion zones exhibited higher values of micro-hardness than the heat-affected zone which contained coarse grains. Charpy impact toughness was higher for the welded joint realized using ER308LN as a filler metal but both types of welds fractured in a ductile mode. [ABSTRACT FROM AUTHOR]

316L stainless steel is commonly used in biomedical applications. However, its use is limited because of its insufficient tribological properties. In this study, a duplex surface modification process of laser melting and plasma nitriding is proposed and wear characteristics of coated 316L stainless steel were investigated. Titanium layers were produced on 316L steel samples at laser powers of 20 and 40 W by selective laser melting. The obtained films were plasma nitrided at 650 and 750 °C for 4 h under a gas mixture of 50% N 2 –50% H 2 . The structural, mechanical, morphological and tribological properties of untreated and processed samples were examined. It was observed that the hardness and wear resistance of coated and plasma nitrided samples were higher than the uncoated and Ti coated samples due to the formation of titanium nitride phases during nitridation. Also, the results indicated that wear resistance of Ti coated and plasma nitrided samples improved with increasing plasma nitriding temperature and laser power. [ABSTRACT FROM AUTHOR]

The definition of process parameters depending on the geometry of the workpiece is one of the main challenges for selective laser melting (SLM). The possibility to use different emission modes is an essential feature of the contemporary fiber lasers, which still requires further attention for controlling the melt pool size. Most of the commercially available SLM systems operate with continuous wave (CW) emission lasers. As a consequence, a substantial effort has been directed toward obtaining full densification by considering the variation of process parameters in CW modality. Pulsed wave (PW) emission achieved by power modulation of a fiber laser is preferred by a smaller fraction of the industrial SLM systems. The differences between the two emission regimes, advantages and disadvantages in their use have not been fully understood. Accordingly, this work proposes a comparative study between the two emission regimes in SLM, namely PW and CW. For this purpose, a single-mode fiber laser is coupled to a prototype SLM system composed of an automated powder bed and a scanner head. The laser source is extensively characterized for pulsed wave emission characteristics in a power modulated regime. Conditions providing the same energy content over the single track are determined and their effect on single-track densification is studied. High-speed imaging is used to observe the differences in the melt pool formation in situ. The overall results confirm that CW emission provides a larger and more stable molten pool during the process, resulting in higher deposition rates. On the other hand, under stable conditions, PW emission provides relatively narrow tracks, which might be problematic for porosity formation and at the same time useful for the production of fine geometries. [ABSTRACT FROM AUTHOR]

This work deals with the execution of micro-pockets on two different materials (AISI 316 L stainless steel and ZrC+10MoSi2 UHT ceramic) using micro-EDM milling. The experiments were carried out by varying process parameters supposed to influence the surface quality, namely discharge pulse-on-time, peak current, voltage, and frequency. For both materials, tungsten carbide cylindrical electrodes were used. The investigation focused on the different results obtained in terms of surface roughness (Sa), kurtosis (Sku), and skewness (Ssk) to evaluate the different finishing level of the surfaces obtained as function of the process parameters. The aim of the present paper is to propose a method for studying the surface characteristics in terms of peaks and valleys shape and distribution, with respect to the mean line, according to ISO 25178. The results of this analysis can provide important information when designing micro-EDM milling processes. [ABSTRACT FROM AUTHOR]

Copyright of Technical Transactions / Czasopismo Techniczne is the property of Sciendo 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.)

In this study, the optimization of pulsed Nd:YAG laser welding parameters was done on the lap-joint of a 316L stainless steel foil with the aim of reducing weld defects through response surface methodology. For this purpose, the effects of peak power, pulse-duration, and frequency were investigated. The most important weld defects seen in this method include underfill and undercut. By presenting a second-order polynomial, the above-mentioned statistical method was managed to be well employed to balance the welding parameters. The results showed that underfill increased with the increased power and reduced frequency, it first increased and then decreased with the increased pulse-duration; and the most important parameter affecting it was the power, whose effect was 65%. The undercut increased with the increased power, pulse-duration, and frequency; and the most important parameter affecting it was the power, whose effect was 64%. Finally, by superimposing different responses, improved conditions were presented to attain a weld with no defects. [ABSTRACT FROM AUTHOR]

In the paper, it is stated that the HfC x N 1-x coating was deposited by magnetron sputtering on the AISI 316L substrate materials at various substrate temperatures ( T s ). The results of XRD and TEM indicated that the HfC x N 1-x coatings were almost amorphous when the T s were below 400 °C, whereas the nanostructured Hf 2 CN was formed at the T s of 400 °C. The Hf 2 CN nanocrystalline formation resulted in a significant improvement in the mechanical properties of HfC x N 1-x coatings. The electrochemical tests demonstrated that the stable HfC x N 1-x coatings improved the corrosion resistance of the AISI 316L. The platelet adhesion tests and hemolysis ratio tests indicated that the HfC x N 1-x coatings presented an improved hemocompatibility when the T s varied from 25 °C to temperatures exceeding 300 °C, which might have occurred due to the surface topography, the interfacial tension and the γ s d / γ s p ratio. [ABSTRACT FROM AUTHOR]

Stainless steels are structural materials used for a wide range of applications. One of the fields of application of these highly corrosion resistant materials is for various medical applications. Different methods of mechanical property improvement have been studied in recent years to increase the durability of components manufactured from these materials. The main goal of this study was an analysis of fatigue strength improvement of the AISI 316Ti austenitic stainless steel by shot peening. A significant improvement of surface hardness, yield strength and fatigue limit by shot peening was observed in this study. This is despite increasing the surface roughness which usually degrades material’s fatigue strength.

In blown powder additive manufacturing technologies the geometrical stability of the built parts is more complex with respect to more conventional powder bed processes. Because of this reason, in order to select the most suitable building parameters, it is important to investigate the shape and the properties of the single metal bead formation and the effect that a scan track has on the nearby ones. In the present study, a methodology to identify an appropriate laser metal deposition process window was introduced, and the effect of the building parameters on the geometry of circular steel samples was investigated. The effect of the scanning strategy on the deposited part was also investigated. This work draws the attention to the importance of the obtainment of the most suitable melt pool shape, demonstrating that the laser power and the scanning strategy have a strong influence not only on the shape but also on the mechanical properties of the final component.

Currently, more than 50 000 different construction materials are available on the market and that number is increasing. Many new materials are often difficult to machine with conventional methods that are currently dominating in production facilities, so the industry is more and more turning to non-traditional machining processes such as abrasive waterjet cutting (AWJC). With the exceptional capabilities that it provides, abrasive waterjet cutting has disadvantages such as surface roughness and striation marks on the cutting surface, which represents a limitation for further application in production. The experimental part of the paper focuses on the verification of the thesis whether conventional material process technologies can be replaced with the abrasive waterjet cutting technology under certain conditions, while maintaining the required quality of the machined surface and productivity. An analysis of the influence of the selected cutting parameters and an optimization of the model was performed on the specimens from the AISI 316L steel on the cutting depth of 25 mm. The results obtained by optimization showed that abrasive waterjet cutting can replace conventional technologies and achieve the required values of the machined surface. [ABSTRACT FROM AUTHOR]

Continuous casting products contain void defects due to the shrinkage occurring during solidification. These defects, having different and irregular shapes and sizes, are located and distributed within the material depending on casting conditions. In order to deliver safe and sound products, these voids must be reduced during the subsequent hot forming processes, but it becomes very difficult when slabs are directly hot rolled without any previous forming processes (i.e., cogging), so obtaining a cheaper and more sustainable process chain. Many studies on voids closure present in literature are based on the evaluation of a process parameter called "stress triaxiality ratio". Aim of this research is to optimize the hot rolling process performed to reduce shrinkage voids of the billet due to casting. In particular, the results of a study on voids closure during hot rolling of stainless steel slabs (AISI 316L) coming from continuous casting process are reported. A FE analysis of the effects of the main process parameters of hot rolling on the “voids closure index” were investigated. Afterwards, experimental tests were performed to validate the research from an industrial point of view. A correlation between the void closure index and the final residual void percentage along the rolled slabs was found. [ABSTRACT FROM AUTHOR]

In this research, the parameters of pulsed Nd:YAG laser welding on the lap-joint of a 316L stainless steel foil were optimized through the response surface methodology with the aim of enhancing the tensile-shear strength. For this purpose, the effects of peak power, pulse-width, and frequency were investigated. The results showed that the analysis of welding parameters in the form of a simple combination of pulse energy could not completely predict welding properties, and the above-mentioned statistical method could appropriately be employed to balance the parameters by modeling and presenting a second-order polynomial. In this model, with the increased power and pulse-width, the strength first increased and then it decreased, and its maxima occurred at a power of 260 W and a pulse-width of 3 ms. The most important parameters affecting this model have been found to be power and pulse-width with impacts of 65 and 25%, respectively. In addition, microscopic studies showed that decrease in strength was because of the undercut and lack of penetration. [ABSTRACT FROM AUTHOR]