TY - JOUR

T1 - Strengthening Mechanisms and Strain Hardening Behavior of 316L Stainless Steel Manufactured by Laser-Based Powder Bed Fusion

AU - Taghipour, Aliakbar

AU - Mazaheri, Yousef

AU - McDavid, Jascha

AU - Sheikhi, Shahram

AU - Braun, Moritz

AU - Shen, Junjun

AU - Klusemann, Benjamin

AU - Ehlers, Sören

N1 - Publisher Copyright: © 2022 Wiley-VCH GmbH.

PY - 2023/2

Y1 - 2023/2

N2 - The microstructure–properties relations and strengthening mechanisms of additively manufactured 316L stainless steel are comprehensively investigated in this work. The orientation dependency and the strain hardening are studied by tensile testing of as-built specimens fabricated by laser-based powder bed fusion (LPBF) in different directions. The results are compared with those obtained for wrought material. The microstructure of the wrought and the LPBF materials are also comprehensively investigated. Equiaxed grains with random orientation and relatively uniform size (≈30 μm) are observed in the wrought material, where the LPBF samples show columnar grains inside as well as fine equiaxed grains in the bottom of the molten pool. A bimodal grain size distribution, higher values of geometrically necessary dislocations density (≈25–32%), and lower fractions of high-angle grain boundaries (≈24–28%) are observed in LPBF 316L. A significant yield strength and considerable ultimate strength improvement without remarkable elongation decrease are obtained for the LPBF tensile specimens, resulting in a high strength-elongation balance (up to 26 122 MPa%). Two-stage strain hardening is depicted in both wrought and LPBF samples. This is successfully predicted with two-stage Hollomon analysis. However, the LPBF samples illustrate lower strain hardening exponents in comparison with the wrought ones.

AB - The microstructure–properties relations and strengthening mechanisms of additively manufactured 316L stainless steel are comprehensively investigated in this work. The orientation dependency and the strain hardening are studied by tensile testing of as-built specimens fabricated by laser-based powder bed fusion (LPBF) in different directions. The results are compared with those obtained for wrought material. The microstructure of the wrought and the LPBF materials are also comprehensively investigated. Equiaxed grains with random orientation and relatively uniform size (≈30 μm) are observed in the wrought material, where the LPBF samples show columnar grains inside as well as fine equiaxed grains in the bottom of the molten pool. A bimodal grain size distribution, higher values of geometrically necessary dislocations density (≈25–32%), and lower fractions of high-angle grain boundaries (≈24–28%) are observed in LPBF 316L. A significant yield strength and considerable ultimate strength improvement without remarkable elongation decrease are obtained for the LPBF tensile specimens, resulting in a high strength-elongation balance (up to 26 122 MPa%). Two-stage strain hardening is depicted in both wrought and LPBF samples. This is successfully predicted with two-stage Hollomon analysis. However, the LPBF samples illustrate lower strain hardening exponents in comparison with the wrought ones.

KW - 316L stainless steel

KW - additive manufacturing

KW - mechanical properties

KW - orientation dependency

KW - strain hardening

KW - Engineering

UR - http://www.scopus.com/inward/record.url?scp=85141206154&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/67e646ab-7197-3d3e-8a7f-e6ef4558d499/

U2 - 10.1002/adem.202201230

DO - 10.1002/adem.202201230

M3 - Journal articles

AN - SCOPUS:85141206154

VL - 25

JO - Advanced Engineering Materials

JF - Advanced Engineering Materials

SN - 1438-1656

IS - 4

M1 - 2201230

ER -