Cyclic response of additive manufactured 316L stainless steel: The role of cell structures

Luqing Cui,Fuqing Jiang,Dunyong Deng,Tongzheng Xin,Xiaoyu Sun,Reza Taherzadeh Mousavian,Ru Lin Peng,Zhiqing Yang,Johan Moverare

doi:10.1016/j.scriptamat.2021.114190

Abstract

We report the effect of cell structures on the fatigue behavior of additively manufactured (AM) 316L stainless steel (316LSS). Compared with the cell-free samples, the fatigue process of fully cellular samples only consists of steady and overload stages, without an initial softening stage. Moreover, the fully cellular sample possesses higher strength, lower cyclic softening rate and longer lifetime. Microscopic analyses show no difference in grain orientations, dimensions, and shapes. However, the fully cellular samples show planar dislocation structures, whereas the cell-free samples display wavy dislocation structures. The existence of cell structures promotes the activation of planar slip, delays strain localization, and ultimately enhances the fatigue performance of AM 316LSS.

Highlights

We report the effect of cell structures on the fatigue behavior of additively manufactured (AM) 316L stainless steel (316LSS)
Among the alloys fabricated by additive manufacturing, 316L stainless steel (316LSS) with face-centered cubic (FCC) structure has attracted huge attentions for its wide application range and the unprecedented mechanical properties [3,4], e.g., the yield strength of 552 MPa and failure elongation of 83.2% was achieved for the AM 316LSS [1], whereas the wrought-annealed sample shows a yield strength of 244 MPa and elongation to failure of 63% [5]
The superior tensile strength is primarily attributed to the notable impediment effect for dislocation motion from the stable cell structures [1], and the Hall-Petch typed strengthening behavior, namely the yield strength scaling with the cell size, is usually applied to rationalize the high strength [2,6]; while the large elongation correlates to the steady and progressive workhardening mechanism provided by the prolific and complicated interactions between dislocations and cell structures [2]

Summary

Introduction

We report the effect of cell structures on the fatigue behavior of additively manufactured (AM) 316L stainless steel (316LSS). In deformed as-built samples, typical dislocation substructures include SBs, SFs and DTs (Fig. 3).

Results

Conclusion