scholarly journals The Fracture Behavior of 316L Stainless Steel with Defects Fabricated by SLM Additive Manufacturing

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1542
Author(s):  
Hui Li ◽  
Jianhao Zhang
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
Crack Propagation ◽  
316L Stainless Steel ◽  
Material Model ◽  
Multiple Crack ◽  
Micro Cracks ◽  
Void Defects ◽  
Fracture Behaviors ◽  
Pairwise Force

In this paper, the fracture behaviors of 316L stainless steel with defects fabricated by the Selective Laser Melting (SLM) additive manufacturing are studied by a peridynamic method. Firstly, the incremental formulations in the peridynamic framework are presented for the elastic-plastic problems. Then, the pairwise force of a bond for orthotropic material model is proposed according to both the local and the global coordinate systems. A simple three-step approach is developed to describe the void defects that generated in the processing of the SLM additive manufacturing in the numerical model. Next, some representative numerical examples are carried out, whose results explain the validation and accuracy of the present method, and demonstrate that the orthotropic features, micro-cracks and voids of the materials have a significant influence on the ultimate bearing capacity, crack propagation and branching of the corresponding structures. It is also revealed that the crack initiations are induced actively by the defects and the crack branching is contributed to the complex multiple-crack propagation. Finally, the achievements of this paper lay a foundation for the engineering applications of the SLM additive manufacturing materials.

Additive Manufacturing of 316L Stainless Steel by a Printing-Debinding-Sintering Method: Effects of Microstructure on Fatigue Property

2021 ◽  
Vol 143 (9) ◽  
Author(s):  
Dayue Jiang ◽  
Fuda Ning
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Additive Manufacturing ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
316L Stainless Steel ◽  
High Energy ◽  
Fatigue Properties ◽  
Crack Growth Model

Abstract Additive manufacturing (AM) technology has been broadly applied to the fabrication of metallic materials. However, current approaches consume either high energy or large investment that considerably elevates their entry threshold. An economic extrusion-based AM method followed by debinding and sintering could efficiently produce the metal parts with relatively low cost and high material utilization. However, an in-depth analysis of the fatigue performance of the component built by such a technology has been little documented so far. Herein, the 316L stainless steel was fabricated throughout the printing-debinding-sintering (PDS) pathway and its fatigue properties were comprehensively assessed. Tensile and flexural fatigue tests were conducted to reveal the fatigue strength and fractural behaviors under different loading conditions, while the fatigue crack growth (FCG) test was performed to quantify the crack propagation. The results indicated the number of 105 cycles can be reached for the tensile specimens under the fatigue loading of 120 MPa, whereas 1.37 × 105 cycles were endured by the flexural specimens under 150 MPa. The fractural morphology indicated an adverse impact of the pore-induced voids on the tensile fatigue crack propagation, but such a drawback could be alleviated in the flexural loading condition. The FCG test unveiled the crack growth rate with the number of cycles and determined the material-related coefficients in the fatigue crack growth model. The research findings provided valuable insights into the effects of the PDS process and microstructures on the resultant fatigue properties of the metal component.

Effect of contaminations on the acoustic emissions during wire and arc additive manufacturing of 316L stainless steel

2021 ◽  
pp. 102585
Author(s):  
André Ramalho ◽  
Telmo G. Santos ◽  
Ben Bevans ◽  
Ziyad Smoqi ◽  
Prahalad Rao ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
316L Stainless Steel ◽  
Acoustic Emissions

scholarly journals A Comparative Study of the CMT+P Process on 316L Stainless Steel Additive Manufacturing

2020 ◽  
Vol 10 (9) ◽  
pp. 3284 ◽  
Author(s):  
Bin Xie ◽  
Jiaxiang Xue ◽  
Xianghui Ren ◽  
Wei Wu ◽  
Zhuangbin Lin
Keyword(s):  
Tensile Strength ◽  
Stainless Steel ◽  
Additive Manufacturing ◽  
Tensile Test ◽  
Heat Dissipation ◽  
316L Stainless Steel ◽  
Single Channel ◽  
Steel Wire ◽  
Energy Dispersive Spectrometer ◽  
Test Method

Adopting the cold metal transfer plus pulse (CMT + P) process, 316L stainless steel wire was treated with a single channel multi-layer deposition experiment under different linear energy. The microstructures of different regions on the deposited samples were observed by optical microscope and scanning electron microscope, and the element distribution in the structure was analyzed by energy dispersive spectrometer. The mechanical properties and microhardness were measured by tensile test method and microhardness tester, respectively, and the anisotropy of tensile strength in horizontal and vertical directions were calculated. Finally, the fracture morphology of the tensile samples were observed by SEM. Experiment results showed that when the difference between the actual and the optimal wire feeding speed matching the specific welding speed was too large, this led to an unstable deposition process as well as flow and collapse of weld bead metal, thus seriously deteriorating the appearance of the deposition samples. The results from metallographic micrograph showed that rapid heat dissipation of the substrate caused small grains to generate in the bottom region of deposition samples, then gradually grew up to coarse dendrites along the building direction in the middle and top region caused by the continuous heat accumulation during deposition. Tensile test results showed that with the increase of linear energy, the horizontal and vertical tensile strength of the as-deposited samples decreased. In addition, the higher linear energy would deteriorate the microstructure of as-deposited parts, including significantly increasing the tendency of oxidation and material stripping. The microhardness values of the bottom, middle and top regions of the samples fluctuated along the centerline of the cross-section, and the values showed a trend of decreasing first and then rising along the building direction. Meanwhile, the yield strength and tensile strength of each specimen showed obvious anisotropy due to unique grain growth morphology. On the whole, the results from this study prove that CMT+P process is a feasible MIG welding additive manufacturing method for 316L stainless steel.

scholarly journals Effect of Powder Feedstock on Microstructure and Mechanical Properties of the 316L Stainless Steel Fabricated by Selective Laser Melting

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 729 ◽  
Author(s):  
Wei Chen ◽  
Guangfu Yin ◽  
Zai Feng ◽  
Xiaoming Liao
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
316L Stainless Steel ◽  
Hierarchical Structures ◽  
Fine Powder ◽  
Tensile Tests ◽  
Laser Melting ◽  
Powder Feedstock

Additive manufacturing by selective laser melting (SLM) was used to investigate the effect of powder feedstock on 316L stainless steel properties include microstructure, relative density, microhardness and mechanical properties. Gas atomized SS316L powders of three different particle size distribution were used in this study. Microstructural investigations were done by scanning electron microscopy (SEM). Tensile tests were performed at room temperatures. Microstructure characterization revealed the presence of hierarchical structures consisting of solidified melt pools, columnar grains and multiform shaped sub-grains. The results showed that the SLM sample from the fine powder obtained the highest mechanical properties with ultimate tensile strength (UTS) of 611.9 ± 9.4 MPa and yield strength (YS) of 519.1 ± 5.9 MPa, and an attendant elongation (EL) of 14.6 ± 1.9%, and a maximum of 97.92 ± 0.13% and a high microhardness 291 ± 6 HV0.1. It has been verified that the fine powder (~16 μm) could be used in additive manufacturing with proper printing parameters.

scholarly journals Microstructure and Fatigue Damage of 316L Stainless Steel Manufactured by Selective Laser Melting (SLM)

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7544
Author(s):  
Zhentao Wang ◽  
Shanglei Yang ◽  
Yubao Huang ◽  
Cong Fan ◽  
Zeng Peng ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Crack Propagation ◽  
Selective Laser Melting ◽  
316L Stainless Steel ◽  
Fatigue Cracks ◽  
Steel Powder ◽  
Maximum Load ◽  
Optical Microscope ◽  
Laser Melting ◽  
Microcrack Initiation

In this paper, 316L stainless steel powder was processed and formed by selective laser melting (SLM). The microstructure of the sample was studied using an optical microscope, and the fatigue failure of the sample and the characteristics of crack initiation and propagation were analyzed, providing a research basis for the application of SLM-316L. Due to the influence of microstructure and SLM process defects, the fatigue cracks of SLM-316L mainly emerged due to defects such as lack of fusion and pores, while the cracks of rolled 316L initiated at the inclusions near the surface of the specimen. After fatigue microcrack initiation of the SLM-316L specimen, due to the existence of shear stress and tear stress, the crack tip was passivated and Z-shaped propagation was formed. The existence of internal defects in SLM-316L made the microcrack initiation random and diverse. At the same time, the existence of defects affected the crack propagation in the form of bending, bifurcation and bridge, which made the main crack propagation deviate from the maximum load direction.

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