Properties Of 316L Stainless Steel Research Articles

Effect of Tac on Microstructure and Mechanic Properties of 316l Stainless Steel by Selective Laser Melting

Effect of Tac on Microstructure and Mechanic Properties of 316l Stainless Steel by Selective Laser Melting

Effects of Different Process Strategies on Surface Quality and Mechanical Properties of 316L Stainless Steel Fabricated via Hybrid Additive-Subtractive Manufacturing

Effects of Different Process Strategies on Surface Quality and Mechanical Properties of 316L Stainless Steel Fabricated via Hybrid Additive-Subtractive Manufacturing

Sliding Wear Properties of 316L Stainless Steel Produced by Additive/Subtractive Hybrid Manufacturing

Sliding Wear Properties of 316L Stainless Steel Produced by Additive/Subtractive Hybrid Manufacturing

Dynamic properties of 316l stainless steel repaired using electron beam additive manufacturing

Additive manufacturing has the potential to be used for repair of high-value parts, but the strength and integrity of such repaired parts, especially under dynamic loading, in still unknown. This work presents the results of high strain-rate dynamic testing of additively repaired stainless steel samples. The 316L samples were intentionally damaged and subsequently repaired with 308L stainless steel wire using electron beam additive manufacturing. The repaired samples were subjected to gas-gun impact testing to induce incipient damage and determine the role played by the repaired region in dictating damage and failure. The results show the following: 1) the equation of state of the repaired region is comparable to the original material as shown by the unchanged spall plane location, 2) the deformation behavior is similar to the original material as shown by the similar Hugoniot Elastic limit, 3) the spall strength of the repaired region is slightly higher than the original material due to varying grain size, and 4) the damage morphology in the repaired region is different and involves a high rate of void coalescence. Despite these minor differences in the spall strength and the damage morphology, the overall dynamic response of the original material and repaired samples is similar suggesting that AM is a promising approach for repairing high-value components.

Investigation of the Biocompatibility of Laser Treated 316L Stainless Steel Materials

In this study, 316L stainless steel materials, which are widely used in the industry, were produced by investment casting management. Depending on the microstructure, the hardness values constitute an important stage of the properties that can be developed and controlled. For this purpose, the differences between the microstructure and hardness properties of 316L stainless steel, which is produced by the investment casting method, and 316L stainless steel, which is currently used commercially, were examined. The changes caused by the fiber laser on the surface of 316L materials produced with two different production methods were examined. It was observed that the laser used made different changes in the surface structure of the 316L material produced by both methods. Since the surface of the material is a buffer between body fluids and biomaterial, it is known that there is a relationship between surface properties and biocompatibility. In this study, the L929 cell growth test, one of the cytotoxicity tests, was applied and thus, how laser surface treatment affects the biocompatibility of 316L materials produced by both methods was comparatively examined.

Comparison of 316L and Ti6Al4V biomaterial coated by ZrCu-based thin films metallic glasses: Structure, morphology, wettability, protein adsorption, corrosion resistance, biomineralization

In this study, ZrCu-based thin films were obtained using a PVD-cathodic arc technique, aiming to improve the surface properties of 316L stainless steel and Ti6Al4V implant materials. By combining their superior mechanical properties with the corrosion resistance of amorphous metallic glasses, the obtained ZrCu-based layers could be qualified as candidates for medical applications. Ca, Mo, Mg, Si and Sr additions to ZrCu structure were considered and the resulting ternary systems were subjected to a detailed investigation. Potentiodynamic polarization was employed to assess corrosion kinetics and their overall electrochemical behaviour after 1 h immersion in SBF solution, the experiments being conducted at human body temperature (37.0 ± 0.5 °C). Additionally, electrochemical impedance spectroscopy (EIS) was carried out for detecting fast changes of the system under investigation and to reveal in depth information related to coating/substrate–solution interface. For morphology and topography characterization before and after electrochemical tests, scanning electron microscopy was used. The results showed a dependence of mechanical properties on the used substrate: the hardness was higher and a better adhesion was achieved when Ti6Al4V was used. Immersion tests were also influenced by the substrate related outcome, since the coatings deposited on 316L substrate showed a significant degradation compared to those on Ti6Al4V substrate, where the apatite structure formed on the surface was more evident. ToF-SIMS analysis revealed protein adsorption enhanced for all applied coatings.

Effect of annealing on the mechanical and corrosion properties of 316L stainless steel manufactured by laser powder bed fusion

The effect of annealing on the mechanical and corrosion response of 316L stainless steel produced using laser powder bed fusion (LPBF) was investigated. The as-printed materials were subjected to annealing at a temperature of 1000 °C for 2 h. Microstructural observations revealed that after annealing the cellular network inside the grains disappeared, and a slight increase in grain size and the proportion of low-angle grain boundaries (LAGBs) occurred. The most significant microstructural changes occurred with the nano-inclusions, as the annealing resulted in change in their chemical composition, a decrease in their density (number per unit volume), while simultaneously their size increased. All these changes caused a decline in the mechanical properties of the steel and an increase in its susceptibility to localized corrosion.

Effect of electropulsing and annealing treatment on microstructure and mechanical properties of 316L stainless steel

Considering the consumption of time and energy for the traditional heat treatment process, a new heat treatment method with high speed and low energy consumption has always been the direction of researchers. The microstructure and mechanical properties of engineering 316L stainless steel were measured under electropulsing treatment within 400 ns and annealing treatment for 2 h. Compared with the original cold-rolled state, it was found that the yield strength after 3.8 × 103 A/mm2 electropulsing treatment was reduced by 26.2% and that after 800 °C heat treatment was reduced by 27.7%. The nucleation after electropulsing treatment is mainly concentrated at one end of the lamellar grain and finally grows into the square or rhombic grain with an average grain size of 1.5 µm. After annealing, the nucleation is mainly concentrated at the grain boundaries of the lamellae and finally grows into equiaxed grains with an average grain size of 1.8 µm. Under the action of electronic wind, the recrystallization nucleation after electropulsing is mainly dominated by the mechanism of subgrain nucleation and growth. However, under the action of a uniform thermal field, the recrystallization nucleation after annealing is mainly based on the grain boundary bow-out mechanism.

High-power laser powder bed fusion of 316L stainless steel: Defects, microstructure, and mechanical properties

Low build rate has always been the bottleneck problem of the application and development of laser powder bed fusion (LPBF) metal 3D printing technology. Although increasing laser power has been an effective way to break through this technical problem, studies regarding the high power LPBF (HP-LPBF) are still insufficient. Relying upon a self-developed 2000 W level HP-LPBF equipment, this paper investigated the defect characteristics, microstructure, and mechanical properties of 316L stainless steel (SS) LPBF samples fabricated at three different laser power levels (200 W, 1000 W, 2000 W). The results show that hot cracks extending along high angle grain boundaries may form at 1000 W and 2000 W. However, no crack is observed at 200 W. With the optimized process parameters, highly dense (relative density>99.5 %) samples can be obtained at all three laser powers. Moreover, the build rate of the dense sample increases monotonously with the increase of laser power, which are 5.76 cm3/h at 200 W, 36 cm3/h at 1000 W, and 61.2 cm3/h at 2000 W. The dominant grain structures of all the as-built samples are columnar grains growing along the build direction. With the increase of laser power, the columnar grains become coarser in size and higher in proportion, the 〈001〉 texture gets stronger, while the dislocation density decreases slightly. Although the Vickers hardness and room-temperature tensile properties of the LPBF samples fabricated at 1000 W and 2000 W are slightly lower than those of the samples fabricated at 200 W, they are significantly higher than those of 316L SS forgings (ASTM A182M-2016A).

Flaw type dependent tensile properties of 316L stainless steel additively manufactured by laser powder bed fusion

In this laser powder bed fusion (LPBF) study for 316 L stainless steel (316 L SS), the laser scan speed was varied to produce samples with keyhole (KH) and lack of fusion (LoF) flaws, each with three levels of density (i.e., >97%, ∼98%, and ∼99%). KH and LoF flaws were characterized by circularity, size, and aspect ratio from extensive image analysis of optical micrographs. The samples were tested in uniaxial tension to correlate the flaw characteristics with yield strength (YS), ultimate tensile strength (UTS), and elongation at failure (EL%). Results showed that the circularity decreased, while the size and aspect ratio increased for both KH and LoF flaws when the laser scan speed (at constant power) deviates from the LPBF parameters that yields nearly fully dense 316 L SS. Additional to the influence of the density, the YS and UTS of the samples showed more sensitivity to the LoF than KH, while the EL% was comparable between the two types of flaws when the porosity is below 2%. The difference in mechanical properties for the 316 L samples containing KH and LoF flaws with similar density was minimal because of the intrinsically high ductility of the alloy.

Effect of Ultrasonic Impact Strengthening on Surface Properties of 316L Stainless Steel Prepared by Laser Selective Melting

In order to study the effect of ultrasonic impact (UIP) on the microstructure and properties of 316L stainless steel prepared by selective laser melting (SLM), the hardness of the surface layer and depth direction of the sample were tested with a micro hardness tester. Finally, the friction and wear test of the sample was assessed using a friction and wear tester. The electrochemical corrosion test was carried out on the samples before and after the ultrasonic shock using a CHI660E electrochemical workstation. The results show that after the ultrasonic impact on the 316L stainless steel prepared by SLM, the surface produces plastic deformation and work hardening, which improves the hardness of the material surface and enhances the wear resistance of the sample surface. With ultrasound shocks affecting the near surface of the sample, a deformation layer of about 100 μm depth is formed. After the ultrasonic shock treatment, the self -corrosion potential of the sample in the 3.5% NACl solution is slightly higher than the unproofed sample, and the density of the self -corrosion current is also lower than the unproofed sample., indicating that ultrasonic shock can reduce the corrosion rate of the material surface and enhance the abrasion resistance of the sample surface.

Microstructure and properties of 316L stainless steel by selective laser melting under various process parameters

Microstructure and properties of 316L stainless steel by selective laser melting under various process parameters

Effect of printing parameters on the structure and high strain rate deformation behavior of additively manufactured 316L stainless steel

High strain rate deformation is characterized by strain localization and formation of adiabatic shear bands (ASBs), as opposed to the movement of slip systems seen in quasistatic deformation. Several studies have been done on the effect of printing parameters on the structure and properties of 316L stainless steel, little attention has been paid to the high-strain rate deformation behaviour of this material. In this study, the effect of printing parameters on the microstructure and high strain rate deformation behavior of 3D-printed 316L stainless steel alloy was investigated. Printing parameters such as hatch spacing, laser power, scan speed and build direction, and their effect on the microstructure, density, hardness, and high strain rate compressive behaviour of 316L stainless steel alloy are established. The results show that even though increasing laser power leads to a reduction in part porosity and better part consolidation (density), scan speeds had a significant effect on porosity production regardless of laser power and hatch spacing. A scan speed of 750 mm/s generally resulted in the lowest porosities regardless of laser power and hatch spacing (150 W ≤ P ≥ 250 W and 0.08 mm ≤ h ≥ 0.14 mm respectively). Scan speeds of 1250 mm/s would have to be coupled with higher laser powers (P ≥ 200 W) to get relatively similar porosities obtained at 750 mm/s. Regardless of the laser power and hatch spacing, scan speeds ≥1750 mm/s resulted in higher porosities. In addition, increasing hatch spacing, generally, resulted in increasing levels of porosity in the printed samples, with a hatch spacing of 0.08 mm resulting in the lowest levels of porosities while hatch spacing of 0.14 mm resulted in the highest levels of porosities. In terms of Volumetric Energy Density (VED), VEDs between 44 and 139 J/mm3 resulted in the lowest porosities, highest densities, and hardness, regardless of the build directions. In addition, increasing laser power resulted in thicker and tightly packed sub-grain structures whereas, an increase in hatch spacing and scan speed resulted in thinner/loosely packed sub-grain structures, and thinner/tightly packed sub-grain structures, respectively. Regardless of the printing parameters, samples perpendicular to the build direction had higher maximum flow stresses and lower strains when compared with the samples parallel to the build direction during high strain rate impact. Also, any combination of individual printing parameters that result in finer sub-grain structures resulted in a relatively brittle deformation behaviour during high strain rate impact. The formation of ASBs is characterized by refined grains within the region of the ASBs and coarser grains away from the ASBs region.

Effect of Cryogenic Heat Treatment and Heat Treatment on the Influence of Mechanical, Energy, and Wear Properties of 316L Stainless Steel by Selective Laser Melting

Effect of Cryogenic Heat Treatment and Heat Treatment on the Influence of Mechanical, Energy, and Wear Properties of 316L Stainless Steel by Selective Laser Melting

Process study for directed energy deposition of 316L stainless steel with TiB2 metal matrix composites

In addition to laser powder bed fusion, directed energy deposition (DED) is also gaining interest as an effective metal additive manufacturing technique. Due to its system configuration, it is more efficient and flexible for materials development. Therefore, it can be used for processing of metal matrix composites (MMCs) through the use of powder mixture as feedstock. 316L stainless steel has high corrosion resistance, biocompatibility, and ductility. Several studies have shown the feasibility of using DED to process 316L stainless steel. The material properties of 316L stainless steel can be improved using reinforcement particles such as TiB2 to form MMCs. In this study, the effects of process parameters on microstructure and mechanical properties of 316L stainless steel reinforced with TiB2 (316L/TiB2) MMC were studied. The process parameters, including laser power, scanning speed, and hopper speed, were varied and analyzed using Taguchi L9 array. It was found that the process parameters have insignificant effect on the bulk density of the samples produced. Through this study, it is also found that tumble mixing was not suitable for the powder feedstock preparation for MMCs to be processed by DED. The microstructure of DED 316L/TiB2 MMC samples consists of columnar and equiaxed grains. Columnar grains were located within the layers while equiaxed grains were located at the interlayer zones. Fine sub-grains were also observed within these grains and their boundaries were enriched with molybdenum and chromium segregations. Precipitates containing titanium were also observed to segregate at the sub-grain boundaries. Finally, the Vickers microhardness of the DED 316L/TiB2 MMC was found to be similar to pure 316L stainless steel produced by DED.

PENGARUH TEKANAN PEMOTONGAN TERHADAP LAJU KOROSI STAINLESS STEEL 316L DENGAN PROSES ABRASIVE WATER JET CUTTING (AWJ)

The waterjet pressure on the Abrasive Water Jet cutting processes affects all the related to the phenomenon of the material. In this study, the effect of water pressure on the AWJ process on the surface quality and corrosion properties of 316L Stainless steel was investigated. The cutting process is carried out by varying the pressure on the nozzle and with the cutting angle being kept at an angle of 90º to the substrate surface. In this research, Garnet with 200 mesh is used as the abrasive material. The results of the AWJ will be tested for corrosion using the 3-cell electrode method and then the surface topography will be observed using SEM. The results obtained in this study are that the corrosion rate decreases with increasing pressure in the AWJ process, however there is an increase after passing the optimal point, namely at 3500 Psi pressure.

Fatigue properties and S-N curve estimating of 316L stainless steel prepared by SLM

This paper investigates the fatigue properties of 316L stainless steel manufactured by selective laser melting technology (SLM) under hot-isostatic-pressing (HIP) heat-treatment. The fatigue tests of 316L specimens were carried out under pulse tensile cyclic loading to obtain the fatigue performance. To avoid falling into local optima and improve the convergence speed, the dynamic multiswarm particle swarm optimizer (DMS-PSO) algorithm was first introduced for parameter optimization of the three-parameter Weibull distribution model, and then the S-N curves based on the model were obtained. The S-N curves were highly consistent with the metallographic and fractographic phenomena. Besides, both the S-N curves and fractographic analysis show that the resistance of high-stress fatigue fracture is significantly improved by using HIP heat-treatment.

The effect of energy density and porosity structure on tensile properties of 316L stainless steel produced by laser powder bed fusion

Understanding the influence of process parameters and defect structure on the properties of parts produced via laser powder bed fusion (L-PBF) is a fundamental step towards the broader use of additive manufacturing technologies in critical applications. Furthermore, the ability to predict mechanical properties by simply considering information on the process parameters and defects observed via X-ray computer tomography (XCT) allows one to avoid expensive destructive testing, provide an in-depth understanding of the process quality and represents a viable solution towards process optimisation. Most of the previous works showed that energy density could be used as an excellent synthetic indicator to predict the mechanical properties of parts produced by L-PBF. This paper explores the effect of different energy density levels on the tensile properties of 316L stainless steel parts produced by L-PBF. Different from previous works in the literature, the same level of energy density is obtained considering various combinations of process parameters (speed, power and hatch distance). While energy density is shown to be a good synthetic indicator for predicting ultimate tensile strength (UTS) and yield strength (YS), a different behaviour is observed for elongation. Elongation shows a significant variability even when samples are produced at the same level of energy density, which contrasts with results obtained for UTS and YS. Synthetic indices representing the porosity structure are shown to be quite significant for predicting elongation even when the optimal energy density is considered. By combining process parameters with porosity structure, we show that almost a full prediction of the tensile properties can be achieved, paving the way for a significant reduction in expensive destructive tests.

Effect of Process Stopping and Restarting on the Microstructure and Local Property of 316L Stainless Steel Manufactured by Selective Laser Melting Process

Effect of Process Stopping and Restarting on the Microstructure and Local Property of 316L Stainless Steel Manufactured by Selective Laser Melting Process

Effect of Laser Speed and Hatch Spacing on the Corrosion Behavior of 316L Stainless Steel Produced by Selective Laser Melting.

In this work, the corrosion properties of 316L stainless steel (SS) obtained by selective laser melting (SLM) are analyzed. The electrochemical results of samples manufactured with an energy density between 40 and 140 J/mm3 are compared using different hatch distances and laser speeds. The analysis correlates the impact of the microstructure and processing defects of SLM 316L stainless steel on its behavior against corrosion. The optimal manufacturing conditions were selected considering the electrochemical results. Although the samples obtained with an energy density close to 90 J/mm3 show a high resistance to corrosion, their performance depends on the combination of selected parameters, obtaining the best results for an intermediate laser speed and a low hatch distance. These manufacturing conditions produce a higher breakdown potential, a faster repassivation of the steel and reduce the current density on electrochemical test.