Microstructural Characterization and Mechanical Properties of L-PBF Processed 316 L at Cryogenic Temperature

Materials

Zhijian James Shen¹  Yuan Zhong¹  Fredrik Svahn²  Pia Åkerfeldt³  Pragya Mishra³  Farnoosh Forouzan³  Marta-Lena Antti³ 

[1] Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden;GKN Aerospace, 46130 Trollhättan, Sweden;Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, 97187 Luleå, Sweden;

关键词: 316 L stainless steel;    cryogenic temperature;    martensite;    strain-induced martensite;    L-PBF process;   

DOI  :  10.3390/ma14195856

来源: DOAJ

【 摘 要 】

Laser powder bed fusion (L-PBF) has attracted great interest in the aerospace and medical sectors because it can produce complex and lightweight parts with high accuracy. Austenitic stainless steel alloy 316 L is widely used in many applications due to its good mechanical properties and high corrosion resistance over a wide temperature range. In this study, L-PBF-processed 316 L was investigated for its suitability in aerospace applications at cryogenic service temperatures and the behavior at cryogenic temperature was compared with room temperature to understand the properties and microstructural changes within this temperature range. Tensile tests were performed at room temperature and at −196 °C to study the mechanical performance and phase changes. The microstructure and fracture surfaces were characterized using scanning electron microscopy, and the phases were analyzed by X-ray diffraction. The results showed a significant increase in the strength of 316 L at −196 °C, while its ductility remained at an acceptable level. The results indicated the formation of ε and α martensite during cryogenic testing, which explained the increase in strength. Nanoindentation revealed different hardness values, indicating the different mechanical properties of austenite (γ), strained austenite, body-centered cubic martensite (α), and hexagonal close-packed martensite (ε) formed during the tensile tests due to mechanical deformation.

【 授权许可】

Unknown