Enhanced mechanical properties and formability of 316L stainless steel materials 3D-printed using selective laser melting

Additive manufacturing (AM) is rapidly expanding in many industrial applications because of the versatile possibilities of fast and complex fabrication of added value products. This manufacturing process would significantly reduce manufacturing time and development cost for nuclear components. However, the process leads to materials with complex microstructures, and their structural stability for nuclear application is still uncertain. This study focuses on 316L stainless steel fabricated by selective laser melting (SLM) in the context of nuclear application, and compares with a cold-rolled solution annealed 316L sample. The effect of heat treatment (HT) and hot isostatic pressing (HIP) on the microstructure and mechanical properties is discussed. It was found that after HT, the material microstructure remains mostly unchanged, while the HIP treatment removes the materials porosity, and partially re-crystallises the microstructure. Finally, the tensile tests showed excellent results, satisfying RCC-MR code requirements for all AM materials.

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The Effect of Hatch Angles on the Microstructure and Mechanical Properties of Selective Laser Melting 316L Stainless Steel

2020 15th IEEE Conference on Industrial Electronics and Applications (ICIEA) ◽

10.1109/iciea48937.2020.9248216 ◽

2020 ◽

Author(s):

Zhou liu ◽

He Ketai ◽

Hu Qingqiang

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

Selective Laser Melting ◽

316L Stainless Steel ◽

Laser Melting ◽

Microstructure And Mechanical Properties

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Microstructure and Mechanical Properties of 316L Stainless Steel Fabricated Using Selective Laser Melting

MRS Advances ◽

10.1557/adv.2019.251 ◽

2019 ◽

Vol 4 (44-45) ◽

pp. 2431-2439

Author(s):

N. Iqbal ◽

E. Jimenez-Melero ◽

U. Ankalkhope ◽

J. Lawrence

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

Selective Laser Melting ◽

Laser Scanning ◽

316L Stainless Steel ◽

Uniform Elongation ◽

Tensile Tests ◽

Uniaxial Tensile ◽

Laser Melting ◽

Sample Height

ABSTRACTThe microstructure homogeneity and variability in mechanical properties of 316L stainless steel components fabricated using selective laser melting (SLM) have been investigated. The crack free, 99.9% dense samples were made starting from SS316L alloy powder, and the melt pool morphology was analysed using optical and scanning electron microscopy. Extremely fast cooling rates after laser melting/solidification process, accompanied by slow diffusion of alloying elements, produced characteristic microstructures with colonies of cellular substructure inside grains, grown along the direction of the principal thermal gradient during laser scanning. In some areas of the microstructure, a significant number of precipitates were observed inside grains and at grain boundaries. Micro hardness measurements along the build direction revealed slight but gradual increase in hardness along the sample height. Uniaxial tensile tests of as manufactured samples showed the effect of un-melted areas causing scatter in room-temperature mechanical properties of samples extracted from the same SLM build. The ultimate tensile strength (UTS) varied from 458MPa to 509MPa along with a variation in uniform elongation from 3.3% to 14.4%. The UTS of a sample exposed to the Cl- rich corrosion environment at 46oC temperature revealed a similar strength as of the original sample, indicating good corrosion resistance of SLM samples under those corrosion conditions.

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

Metals ◽

10.3390/met8090729 ◽

2018 ◽

Vol 8 (9) ◽

pp. 729 ◽

Cited By ~ 12

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.

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