Creep and creep damage behavior of stainless steel 316L manufactured by laser powder bed fusion

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 830; p. 142223
• Main Authors: Ávila Calderón, L.A., Rehmer, B., Schriever, S., Ulbricht, A., Agudo Jácome, L., Sommer, K., Mohr, G., Skrotzki, B., Evans, A.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 07.01.2022; Elsevier BV
• Subjects: Additive manufacturing; Austenitic stainless steels; Computed tomography; Creep behavior; Creep damage; Creep strength; Creep tests; Damage assessment; Grain boundaries; Hot tensile properties; LPBF 316L; Material properties; Mechanical tests; Melting; Micro-computed tomography; Microstructure; Powder beds; Precipitates; Stainless steel; Tensile tests; Creep behavior; LPBF 316L; Micro-computed tomography; Creep damage; Additive manufacturing; Microstructure; Hot tensile properties
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2021.142223

This study presents a thorough characterization of the creep properties of austenitic stainless steel 316L produced by laser powder bed fusion (LPBF 316L) contributing to the sparse available data to date. Experimental results (mechanical tests, microscopy, X-ray computed tomography) concerning the creep deformation and damage mechanisms are presented and discussed. The tested LPBF material exhibits a low defect population, which allows for the isolation and improved understanding of the effect of other typical aspects of an LPBF microstructure on the creep behavior. As a benchmark to assess the material properties of the LPBF 316L, a conventionally manufactured variant of 316L was also tested. To characterize the creep properties, hot tensile tests and constant force creep tests at 600 °C and 650 °C are performed. The creep stress exponents of the LPBF material are smaller than that of the conventional variant. The primary and secondary creep stages and the times to rupture of the LPBF material are shorter than the hot rolled 316L. Overall the creep damage is more extensive in the LPBF material. The creep damage of the LPBF material is overall mainly intergranular. It is presumably caused and accelerated by both the appearance of precipitates at the grain boundaries and the unfavorable orientation of the grain boundaries. Neither the melt pool boundaries nor entrapped gas pores show a significant influence on the creep damage mechanism. •Creep and tensile tests on LPBF 316L and conventional hot rolled 316L at 600 °C and 650 °C.•The tested LPBF material exhibits a low defect population.•The LPBF material has shorter creep stages and times to rupture and lower stress dependency than the conventional variant.•The cellular structure is considered the main cause of the differences in the duration of the primary creep stage.•The final fracture of the LPBF material overall is mainly intergranular in contrast to the conventional variant.