Competing Influence of Porosity and Microstructure on the Fatigue Property of Laser Powder Bed Fusion Stainless Steel 316L

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Date

2017

Authors

Zhang, Meng
Sun, Chen-Nan
Zhang, Xiang
Chin Goh, Phoi
Wei, Jun
Li, Hua
Hardacre, David

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Publisher

University of Texas at Austin

Abstract

Crack initiation constitutes a large portion of the total life for parts under high cycle fatigue loading. Materials made by the laser powder bed fusion (L-PBF) process contain unavoidable process-induced porosity whose effect on the mechanical properties needs to be considered for fatigue applications. Results from this work show that not all pores in L-PBF parts promote fatigue crack initiation. The length scale of local microstructure defects, i.e. grain boundary, could be larger than the pores and in such cases they are the primary cause for crack initiation. Samples were produced in this work to demonstrate the critical defect size responsible for the transition between the porosity-driven and microstructure-driven failure modes.

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