Properties Of 316L Stainless Steel Research Articles

The Formability and Mechanical Properties of 316L Stainless Steel Fabricated by Pulsed Arc Swing Additive Manufacturing

An austenitic stainless steel 316L deposition specimen is fabricated by cold metal transfer‐based swing arc additive manufacturing (CMT‐SAAM), and its formation, microstructure, and tensile properties are investigated. The results showed that the 316L deposited samples exhibited a multi‐layer structure with a small aspect ratio, and the surface forming accuracy is improved with the increase in the swing amplitude. The remelted zone near the interface is dominated by long grains perpendicular to the fusion line, whereas the deposited zone is dominated by columnar dendrites and shows an <100> orientation. Along the building and transverse direction of the swing deposits, the microhardness distribution is uniform. Compared with rollings and forgings, 316L deposited by using the CMT‐SAAM method has both a higher strength and toughness. The average ultimate tensile strength is 573 MPa, and the elongation at break is 52.6%. The high strength and toughness of 316L specimens are attributed to the fine microstructure, high‐density dislocations, and low‐angle grain boundaries (LAGBs) generated during the CMT‐SAAM process.

Influence of compound field-assisted on the mechanical properties of 316L stainless steel fabricated by laser powder bed fusion

The advantages of field-assisted laser additive manufacturing in optimizing microstructure and performance are increasingly recognized. Recently, we investigated the effects of acoustic field (AF) assisted laser powder bed fusion (LPBF) on the mechanical properties of 316L stainless steel (SS) and 316L SS/WC composite materials. Due to the effects of acoustic streaming and cavitation, acoustic field-assisted LPBF achieved optimized mechanical properties. Building on our previous research on AF-assisted LPBF, we introduced magnetic field (MF) and compound field (MF+AF) to study their effects on the microstructure and mechanical properties of 316L SS, 1 wt% and 3 wt% WC/316L SS. Application of the MF induces induced currents in the melt pool due to the Thomson-Seebek effect. The interaction between the MF and induced currents generates thermoelectric magnetic force (TEMF) and thermoelectric magnetic convection (TEMC), which inhibit the growth of columnar grains and enhance mass and heat transfer in the melt pool. Compound field-assisted LPBF reduced the dislocation density of 316L SS, refined grain size, alleviated the concentration distribution of grain orientation, and the ultimate tensile strength of the samples reached 777 MPa and the elongation at break reached 57.5%. Interestingly, for WC/316L SS, both MF and compound field resulted in a decrease in tensile performance, with ultimate tensile strengths as low as 677 MPa and elongations at break as low as 25.1%. This is because the MF affects the uniform distribution of WC particles, causing significant agglomeration and severe unmelted defects in the composite material, leading to a decrease in tensile performance.

Improving the fatigue property of 316L stainless steel through direct energy deposition technology

In this study, to improve the fatigue strength of coarse grain 316L stainless steel, the hard 17-4ph martensitic stainless steel was deposited on the surface of hot rolled 316L based on direct energy deposition (DED) additive manufacturing technology. The 17-4ph deposition and 316L substrate are well connected without any cracking phenomenon which lays the foundation of good mechanical properties. The 17-4ph deposition presents a gradient structure, its fraction of body centered cubic (BCC) phase gradually increases from 0 vol% of substrate to 99.3 vol% of top surface, and its grain size gradually decreases from 53.2 μm near the substrate to 5.1 μm of the top surface, leading to the hardness of deposition gradually increases from 187 Hv to 436 Hv. The fatigue property of 17-4ph coated 316L is significantly improved. Specifically, the fatigue strength in high cycle fatigue (HCF) regime (at the fatigue life of 2 × 106 cycles) is 64 % higher than coarse-grained 316L, while the increment in low cycle fatigue (LCF) regime (at the fatigue life of 104 cycles) is up to 100 %. The improvement in LCF regime of 17-4ph coated 316L is higher than that of HCF regime, which is exactly opposite to the improvement in HCF and LCF regime of samples fabricated by traditional surface strengthening processes. Based on advanced characterization techniques, the potential strengthening mechanism in 17-4ph coated 316L was studied. It is expected that this study can provide reference for the application of additive manufacturing technology in the field of surface strengthening.

Improving Fatigue Properties of 316L Stainless Steel Welded Joints by Surface Spinning Strengthening

Improving Fatigue Properties of 316L Stainless Steel Welded Joints by Surface Spinning Strengthening

EFFECT OF MICRO-TEXTURES AND CrAlSiN COATINGS ON THE FRICTION AND WEAR PROPERTIES OF 316L STAINLESS STEELS IN SEAWATER

This paper aims to provide a method for improving the tribological properties of 316L stainless steels in seawater. During the experimental process, laser texturing technology was used to create biomimetic micro-textures inspired by turtle shell patterns on the 316L stainless steel surfaces. Then, CrAlSiN coating was deposited on the textured surface using the physical vapor deposition (PVD) technique, allowing us to study the frictional properties of the samples in both atmospheric and seawater environments. The results showed that, compared to polished 316L stainless steel, the specimens treated with micro-texture and CrAlSiN coating exhibited a reduction in wear rate by 52.1% and 71.8% under atmospheric and seawater friction conditions, respectively. Under atmospheric friction conditions, the micro-textures had a limited effect on reducing the friction of the 316L stainless steel substrate. However, the CrAlSiN coating, due to its excellent mechanical properties, significantly improved the wear resistance of the 316L stainless steel. Under seawater friction conditions, the continuous CrAlSiN coating played a role in reducing 316L stainless steel wear and seawater corrosion. At the same time, the micro-textures acted as reservoirs for wear debris and seawater, forming a more stable seawater lubricating film and reducing the friction coefficient. Therefore, the synergistic effect of the CrAlSiN coating and biomimetic micro-textures demonstrated remarkable improvement in the tribological performance of 316L stainless steel in seawater environments.

Investigation of Microstructures and Tensile Properties of 316L Stainless Steel Fabricated via Laser Powder Bed Fusion.

In this study, a thorough investigation of the microstructures and tensile properties of 316L stainless steel fabricated via laser powder bed fusion (L-PBF) was done. 316L stainless steel specimens with two different thicknesses of 1.5 mm and 4.0 mm fabricated under similar conditions were utilized. Microstructural characterization was performed using optical microscopy (OM) and scanning electron microscopy (SEM) equipped with electron backscatter diffraction (EBSD). Melt pools and cellular structures were observed using OM, whereas EBSD was utilized to obtain the grain size, grain boundary characteristics, and crystallographic texture. The 1.5 mm thick sample demonstrated a yield strength (YS) of 538.42 MPa, ultimate tensile strength (UTS) of 606.47 MPa, and elongation to failure of 69.88%, whereas the 4.0 mm thick sample had a YS of 551.21 MPa, UTS of 619.58 MPa, and elongation to failure of 73.66%. These results demonstrated a slight decrease in mechanical properties with decreasing thickness, with a 2.4% reduction in YS, 2.1% reduction in UTS, and 5.8% reduction in elongation to failure. In addition to other microstructural features, the cellular structures were observed to be the major contributors to the high mechanical properties. Using the inverse pole figure (IPF) maps, both thicknesses depicted a crystallographic texture of {001} <101> in their as-built state. However, when subjected to tensile loads, texture transitions to {111} <001> and {111} <011> were observed for the 1.5 mm and 4.0 mm samples, respectively. Additionally, EBSD analysis revealed the pre-existence of high-density dislocation networks and a high fraction of low-angle grain boundaries. Interestingly, twinning was observed, suggesting that the plastic deformation occurred through dislocation gliding and deformation twinning.

Influence of the Processing Parameters on the Microstructure and Mechanical Properties of 316L Stainless Steel Fabricated by Laser Powder Bed Fusion

Complex thermo-kinetic interactions during metal additive manufacturing reduce the homogeneity of the microstructure of the produced samples. Understanding the effect of processing parameters over the resulting mechanical properties is essential for adopting and popularizing this technology. The present work is focused on the effect of laser power, scanning speed, and hatch spacing on the relative density, microhardness, and microstructure of 316L stainless steel processed by laser powder bed fusion. Several characterization techniques were used to study the microstructure and mechanical properties: optical, electron microscopies, and spectrometry. A full-factorial design of experiments was employed for relative density and microhardness evaluation. The results derived from the experimental work were subjected to statistical analysis, including the use of analysis of variance (ANOVA) to determine both the main effects and the interaction between the processing parameters, as well as to observe the contribution of each factor on the mechanical properties. The results show that the scanning speed is the most statistically significant parameter influencing densification and microhardness. Ensuring the amount of volumetric energy density (125 J/mm3) used to melt the powder bed is paramount; maximum densification (99.7%) is achieved with high laser power and low scanning speed, while hatch spacing is not statistically significant.

Comprehensive Investigation of the Mechanical Properties of 316L Stainless Steel Processed via Laser Powder Bed Fusion

Comprehensive Investigation of the Mechanical Properties of 316L Stainless Steel Processed via Laser Powder Bed Fusion

Effects of multiaxial non-proportional cyclic pre-hardening on monotonic tensile and fatigue properties of 316L stainless steel

Effects of multiaxial non-proportional cyclic pre-hardening (CPH) treatment by performing tension–torsion cyclic test in a circular path on the monotonic tensile and fatigue properties of 316L austenitic stainless steel are studied. Results show that the circular path pre-hardening treatment significantly improves the yield strength but reduces the elongation of materials in comparison with the as-received (AR) material. Moreover, the fatigue resistance of 316L stainless steel after CPH treatment gets markedly degraded at the strain amplitude of 0.4 % with a 26 % decrease of fatigue life, however, the 62 % life increase is obtained at the lower strain amplitude of 0.2 %. Therefore, it is reasonable to believe that the CPH treatment can be regarded as an effective method to increase the fatigue resistance within a certain range of strain amplitude if the proper loading path and cycles of the multiaxial pre-hardening process are used. The different life variations at the high and low strain amplitudes are explained from the perspectives of macroscopic deformation energy and microscopic deformation modes based on EBSD and TEM characterizations.

Effect of re-lasing on the fatigue properties of 316L Stainless Steel Produced by laser powder bed fusion

Despite the great success of the metal additive manufacturing process by Laser Fusion on Powder Bed (L-PBF), this technique still lacks maturity in several areas. Among its major challenges, the low fatigue strength of the L-PBF parts is caused, among other features, by two main types of defects. Firstly, the L-PBF process generates a high surface roughness, mainly linked to the phenomenon of partial powder melting on the part surface. Secondly, internal defects are created during the building process and are randomly distributed in the material. The present study investigates the effect of a second lasing on the improvements of the surface roughness, defects population as well as fatigue properties of L-PBF parts. Based on preliminary experiments, two re-lasing strategies were selected. A high cycle fatigue campaign was subsequently carried out with a stress ratio of R= -1 on samples with or without re-lasing, in the as-built state or after polishing. Specimens printed in Net-Shape showed even after re-lasing and polishing, a much lower fatigue strength than those machined in the bulk after additive manufacturing. In addition, results show that the tested re-lasing conditions has a beneficial effect on the quasi-static and fatigue strength of the 316L obtained by L-PBF.

Investigation into the effect of process parameters on density, surface roughness, and mechanical properties of 316L stainless steel fabricated by selective laser melting

Investigation into the effect of process parameters on density, surface roughness, and mechanical properties of 316L stainless steel fabricated by selective laser melting

Biaxial tensile behavior of stainless steel 316L manufactured by selective laser melting

In this study, miniaturized cruciform biaxial tensile specimens were optimized by finite element simulation software Ansys to vary five geometric parameters. The optimized specimens were utilized to characterize the biaxial tensile properties of 316L stainless steel fabricated through selective laser melting (SLM), with the two loading directions being vertical (X) and parallel (Y) to the building direction. It was discovered that at load ratios of 4:2 and 2:4, the yield strengths along X and Y orientations reached their respective maxima. By comparing the experimentally obtained yield loci against predictions by theoretical criteria including Mises, Hill48 and Hosford, it was found that the Hill48 anisotropic criterion corresponded most closely with the experimental results, while the other two criteria exhibited considerably larger deviations. Therefore, Hill48 was concluded to most accurately describe the yielding behaviors of SLM 316L under complex loading conditions.

Effect of bimodal powder on densification and mechanical properties of 316L stainless steel fabricated by binder jet 3D printing

Obtaining fully densified metal parts presents significant challenges for binder jet 3D printing (BJ3DP). Replacing the unimodal powder feedstocks with bimodal powders provided a promising approach to increasing the densities of the printed parts. While it was demonstrated that bimodal powders increase the packing density of the powder bed, research into their effects on the green parts and the capabilities of the final components remains limited. In this study, bimodal 316 L stainless steel (SS) powders with three different coarse-fine ratios, including fine fraction proportions of 10 wt% (#C90F10), 15 wt% (#C85F15), and 20 wt% (#C80F20), were printed with green relative densities of approximately 59.0 %, 59.9 %, and 60.9 %, respectively. The densities of the green samples exhibited a positive correlation with the fine fraction proportions. Subsequent sintering at 1400 °C for 3 h revealed that the densification effect did not increase linearly with increasing fine fraction due to agglomeration. The #C80F20 sintered samples exhibited optimal mechanical properties, relative densities of approximately 92.8 %, tensile yield strengths (YS) of ∼202 MPa, ultimate tensile strengths (UTS) of ∼477 MPa, and elongations of ∼54.7 %. The results of this study provide valuable insights into densification and strengthening with bimodal powder and open new avenues for the use of BJ3DP to produce fully densified metal parts.

Effect of dual-laser powder bed fusion on surface quality, internal defects and properties of 316L stainless steel

Dual-laser powder bed fusion has excellent potential in the preparation of high-performance components due to its ability to suppress defects and control properties during the formation. This paper investigates the effects of various remelting intervals and remelting laser power on the mechanical properties, internal defects, and surface quality of dual-laser powder bed fusion 316L. Compared to increasing laser power, shortening melting intervals offers a more effective compensation for energy losses resulting from the rapid cooling effects of LPBF. Higher surface quality (Ra = 5.876, Str = 0.633) and higher relative density (99.28 %) can be attained with a shorter remelting interval. However, due to excessive energy that increases porosity and grain size, the improvement in mechanical properties (667.19 MPa, 49.3 %) is less than long-interval remelting (703.55 MPa, 50.4 %). In comparison to vary remelting time interval at the high laser power, the depth of the melting pool can be controlled more precisely within a shorter interval by varying the laser power. However, the semi-melting of the spatter caused by applying a medium remelting laser power introduces new lack of fusion voids. This study highlights the advantages of dual-laser powder bed fusion in ensuring consistent formation and demonstrates its potential for producing customized microstructures and high-quality surfaces. Furthermore, it presents a novel approach for the dual-laser powder bed fusion of high refractive materials and room temperature brittleness materials.

Microstructure and mechanical properties of 316L stainless steel of selected laser sintering

In recent years, additive manufacturing (AM) has received global attention, because the AM can manufacture irregular and complex-shaped parts and reduce material waste. In this paper, the 316L stainless steel powder was made into a structure conforming to the size of ASTM E8 by the selected laser sintering (SLS). The AM parameters were set as fixed laser power (220 W) and layer thickness of 0.03 mm, as well as scanning speed (900 mm/s and 800 mm/s), different annealing temperatures (750°C, 850°C and 950°C), and time (3 minutes, 6 minutes and 9 minutes). The results show that the optimal tensile strength was 639 MPa when the scanning speed was 800 mm/s, and the annealing temperature and time were 750°C and 3 minutes, respectively. In addition, the maximum elongation was 43% when the annealing temperature and time were 850°C for 6 minutes and 9 minutes, and 950°C for 9 minutes. The as-SLS of fast and slow scanning speeds were compared, the maximum tensile strength increased from 575 MPa to 639 MPa (increased by 11.1%), and the elongation increased from 21% to 32% (increased by 13.1%). The significant records of the 316L mechanical properties are extremely important for the fundamental understanding of SLS.

Quaternary ZrCuCa-based thin films metallic glasses deposited by cathodic arc deposition

The current study’s aim is to obtain quaternary ZrCuCa based thin films using a physical vapor deposition method (PVD) - cathodic arc approach – in order to improve the surface properties of 316L stainless steel and Ti6Al4V implantable materials. The developed ZrCuCa-based layers could be potential candidates in the medical industry if they are able to combine their exceptional mechanical properties with the corrosion resistance of amorphous metallic glasses. Furthermore, addition of Mo, Mg, Si, and Sr was taken into consideration for the ZrCuCa structure and the resulted quaternary systems were analysed in detail, through electrochemical tests and bioactivity assay, which were carried out in synthetic body fluid (SBF) at human body temperature (37 °C). Surface morphology and roughness of the specimens before and after the tests were also evaluated. The results showed that regardless the substrate type, the roughness of the surface has increased for all coatings from 19 nm for 316L, and 50 nm for Ti6Al4V, to 2000 nm). The adhesion of obtained coatings was reached from 8 N to 18, the coatings on Ti6Al4V alloy was found to be from 12 N to 18 N, while on 316L steel was from 8 N to 15 N, indicating that the coatings deposited on Ti alloy have a better adhesion. The corrosion current density parameter for ZrCuCaMo and ZrCuCaMg sjowe the lowest value (316L: 21.99 µA/cm2 and 11.37 µA/cm2; Ti6Al4V: 1.62 µA/cm2 and 13.37 µA/cm2), indicating the best corrosion resistance. The mass evolution of the coatings deposited on 316L was ranged from the −0.47 mg to 1.37 mg, while for those deposited on Ti6Al4V, the values were ranged from −0.08 mg to 2.66 mg, indicating a degradation and biomineralization process, respectively. In conclusion, the electrochemical studies and bioactivity experiments demonstrated that the suggested coatings improve the substrate’s behaviour in simulated conditions, highlighting their potential as biomaterials.

Enhancement of Surface Properties of 316L Stainless Steel with Silver Nanoparticles using Airbrush Spray Process

In this study, the surfaces of 316L stainless steel, which is frequently preferred in biomedical applications, were modified with silver nanoparticles (Ag NPs) to improve their antibacterial and anticorrosive properties. Firstly, Ag NPs were synthesized using a completely green a plant-mediated ultrasound-assisted synthesis method and characterized. Next, Ag NPs were coated onto the surface of the 316L with the airbrush spray technique. The coated surfaces were examined by SEM, surface roughness, profilometer, optical microscope, electrochemical corrosion, and disk diffusion analyses. The average surface roughness values of the surface modified samples were found to be moderately suitable for use in biomaterials while exhibiting corrosion resistance and antibacterial resistance. The Ag NPs coating offers significant potential for biomedical applications.

Effects of Deposition Strategies on Microstructure and Mechanical Properties of 316L Stainless Steel and Inconel 625 Alloy Dissimilar Structure Fabricated by Cold Metal Transfer Arc Additive Manufacturing

Effects of Deposition Strategies on Microstructure and Mechanical Properties of 316L Stainless Steel and Inconel 625 Alloy Dissimilar Structure Fabricated by Cold Metal Transfer Arc Additive Manufacturing

Effect of boron element on microstructure and mechanical properties of 316L stainless steel manufactured by selective laser melting

Boron(B)element is often utilized to enhance mechanical properties of stainless steel due to its excellent performance. In this study, selective laser melting (SLM) was used to print 316L/B stainless steel with varying boron weight content. The effects of boron content on microstructure, nanoindentation, and mechanical properties of the printed 316L stainless steel were discussed. Fine cell dendrites and columnar crystals were found in the SLM printed stainless steel due to the rapid solidification in SLM. It was found that boron has a higher growth limiting factor in the iron system and the boron solute can provide a high component supercooling. By adding boron element to stainless steel during printing, the honeycomb and grain size after solidification are significantly reduced due to interactions between the boron element and the 316L. Tensile testing results show that the ultimate tensile strength of the SLM fabricated parts with 0.5 wt% and 1 wt% boron element addition can be increased significantly to 1071 MPa and 1174 MPa, respectively.

Effect of TaC on microstructure and mechanical properties of 316L stainless steel by selective laser melting

Selective laser melting (SLM) is a rapid processing technology used to directly manufacture metal terminal components. TaC is often utilized to enhance mechanical properties of metal due to its excellent performance. In this study, SLM was employed to manufacture TaC/316 L composites with varying TaC volume content. The effect of TaC content on the microscopic appearance and mechanical properties of SLM-316 L stainless steel was then explored. The TaC admixture was efficiently and effectively distributed on 316 L powder particle surfaces using short-duration high energy ball milling. Under the optimal parameters for SLM, the relative densities of the specimens reached over 99.0% because of the high wettability of 316 L with TaC. Moreover, grain refinement was observed after microstructural analysis due to interactions between the TaC and 316 L. Tensile, Charpy impact, and microhardness tests demonstrated that the adjunction of 0.5 vol% and 1.5 vol% TaC provided a significantly enhanced yield strength (increased by 7.4% and 30.9%), ultimate tensile strength (increased by 5.6% and 27.1%), and microhardness (increased by 9.9% and 22.7%). The impact toughness (reduced by 20.3% and 51.4%) and ductility (reduced by 23.1% and 39.5%) were maintained.