Mechanical and Corrosion Properties of Gas and Water Atomized Laser-Powder Bed Fusion Fabricated 25Cr7Ni Stainless Steel

Purpose The purpose of this paper is to investigate effects of layer thickness on densification, surface morphology, microstructure and mechanical and corrosion properties of 420 stainless steel fabricated by laser-powder bed fusion (L-PBF). Design/methodology/approach Standard specimens were printed at layer thickness of 10, 20 and 30 µm to characterize Archimedes density, surface roughness, tensile strength, elongation, hardness, microstructural phases and corrosion performance in the as-printed and heat-treated condition. Findings Archimedes density slightly increased from 7.67 ± 0.02 to 7.70 ± 0.02g/cm3 and notably decreased to 7.35 ± 0.05 g/cm3 as the layer thickness was changed from 20 µm to 10 and 30 µm, respectively. The sensitivity to layer thickness variation was also evident in properties, the ultimate tensile strength of as-printed parts increased from 1050 ± 25 MPa to 1130 ± 35 MPa and decreased to 760 ± 35 MPa, elongation increased from 2.5 ± 0.2% to 2.8 ± 0.3% and decreased to 1.5 ± 0.2, and hardness increased from 55 ± 1 HRC to 57 ± 1 HRC and decreased to 51 ± 1 HRC, respectively. Following heat treatment, the ultimate tensile strength and elongation improved but the general trends of effects of layer thickness remained the same. Practical implications Properties obtained by L-PBF are superior to reported properties of 420 stainless steel fabricated by metal injection molding and comparable to wrought properties. Originality/value This study successfully the sensitivity of mechanical and corrosion properties of the as-printed and heat-treated parts to not only physical density but also microstructure (martensite content and tempering), as a result of changing the layer thickness. This manuscript also demonstrates porosity evolution as a combination of reduced energy flux and lower packing density for parts processed at an increasing layer thickness.

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Modeling of solidification microstructure evolution in laser powder bed fusion fabricated 316L stainless steel using combined computational fluid dynamics and cellular automata

Additive Manufacturing ◽

10.1016/j.addma.2019.06.024 ◽

2019 ◽

Vol 28 ◽

pp. 750-765 ◽

Cited By ~ 4

Author(s):

Yi Zhang ◽

Jing Zhang

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Stainless Steel ◽

Cellular Automata ◽

Microstructure Evolution ◽

316L Stainless Steel ◽

Solidification Microstructure ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed

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Fracture toughness of 304L austenitic stainless steel produced by laser powder bed fusion

Scripta Materialia ◽

10.1016/j.scriptamat.2021.114002 ◽

2021 ◽

Vol 202 ◽

pp. 114002

Author(s):

Punit Kumar ◽

Zhiguang Zhu ◽

Sharon M.L. Nai ◽

R.L. Narayan ◽

U. Ramamurty

Keyword(s):

Fracture Toughness ◽

Stainless Steel ◽

Austenitic Stainless Steel ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed

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Crystallographic orientation dependence of Charpy impact behaviours in stainless steel 316L fabricated by laser powder bed fusion

Additive Manufacturing ◽

10.1016/j.addma.2021.102104 ◽

2021 ◽

pp. 102104

Author(s):

Xianglong Wang ◽

Oscar Sanchez-Mata ◽

Sıla Ece Atabay ◽

Jose Alberto Muñiz-Lerma ◽

Mohammad Attarian Shandiz ◽

...

Keyword(s):

Stainless Steel ◽

Crystallographic Orientation ◽

Charpy Impact ◽

Orientation Dependence ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Stainless Steel 316L ◽

Powder Bed

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Effect of Build Orientation on the Microstructure, Mechanical and Corrosion Properties of a Biodegradable High Manganese Steel Processed by Laser Powder Bed Fusion

Metals ◽

10.3390/met11060944 ◽

2021 ◽

Vol 11 (6) ◽

pp. 944

Author(s):

Martin Otto ◽

Stefan Pilz ◽

Annett Gebert ◽

Uta Kühn ◽

Julia Hufenbach

Keyword(s):

Electron Backscatter Diffraction ◽

Longitudinal Axis ◽

Manganese Steel ◽

Compressive Yield Strength ◽

Powder Bed Fusion ◽

Compression Tests ◽

Laser Powder Bed Fusion ◽

Corrosion Properties ◽

Powder Bed ◽

Manufacturing Technologies

In the last decade, additive manufacturing technologies like laser powder bed fusion (LPBF) have emerged strongly. However, the process characteristics involving layer-wise build-up of the part and the occurring high, directional thermal gradient result in significant changes of the microstructure and the related properties compared to traditionally fabricated materials. This study presents the influence of the build direction (BD) on the microstructure and resulting properties of a novel austenitic Fe‑30Mn‑1C‑0.02S alloy processed via LPBF. The fabricated samples display a {011} texture in BD which was detected by electron backscatter diffraction. Furthermore, isolated binding defects could be observed between the layers. Quasi-static tensile and compression tests displayed that the yield, ultimate tensile as well as the compressive yield strength are significantly higher for samples which were built with their longitudinal axis perpendicular to BD compared to their parallel counterparts. This was predominantly ascribed to the less severe effects of the sharp-edged binding defects loaded perpendicular to BD. Additionally, a change of the Young’s modulus in dependence of BD could be demonstrated, which is explained by the respective texture. Potentiodynamic polarization tests conducted in a simulated body fluid revealed only slight differences of the corrosion properties in dependence of the build design.

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Corrosion Fatigue Characteristics of 316L Stainless Steel Fabricated by Laser Powder Bed Fusion

Metals ◽

10.3390/met11071046 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1046

Author(s):

Balachander Gnanasekaran ◽

Jie Song ◽

Vijay Vasudevan ◽

Yao Fu

Keyword(s):

Fatigue Crack ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

Corrosion Fatigue ◽

Fatigue Properties ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Corrosion Properties ◽

Powder Bed ◽

Fatigue Characteristics

Laser powder bed fusion (LPBF) has been increasingly used in the fabrication of dense metallic structures. However, the corrosion related properties of LPBF alloys, in particular environment-assisted cracking, such as corrosion fatigue properties, are not well understood. In this study, the corrosion and corrosion fatigue characteristics of LPBF 316L stainless steels (SS) in 3.5 wt.% NaCl solution have been investigated using an electrochemical method, high cycle fatigue, and fatigue crack propagation testing. The LPBF 316L SSs demonstrated significantly improved corrosion properties compared to conventionally manufactured 316L, as reflected by the increased pitting and repassivation potentials, as well as retarded crack initiation. However, the printing parameters did not strongly affect the pitting potentials. LPBF samples also demonstrated enhanced capabilities of repassivation during the fatigue crack propagation. The unique microstructural features introduced during the printing process are discussed. The improved corrosion and corrosion fatigue properties are attributed to the presence of columnar/cellular subgrains formed by dislocation networks that serve as high diffusion paths to transport anti-corrosion elements.

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