Adiabatic shear band development and following failure in 316L fabricated by an additive manufacturing process

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2021-04, Vol.811, p.141003, Article 141003
• Main Authors: Chen, Jie, Bao, Kuo, Zhang, Xianfeng, Cao, Yang, Peng, Yong, Kong, Jian, Wang, Kehong
• Format: Article
• Language: English
• Subjects: 316L; Additive manufacturing; Adiabatic flow; Adiabatic shear band; Deformation; Ductile fracture; Ductile-brittle transition; Dynamic loads; Dynamic recrystallization; Edge dislocations; Failure; Hardening rate; Shear bands; Shear planes; Stainless steels; Strain hardening; Strain rate sensitivity; Temperature distribution; Texture; Twinning; Yield strength
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2021.141003

Although adiabatic shear band(ASB) have been studied for decades. Reports about this deformation mode in materials made by additive manufacturing process remain insufficient. Here we investigate the adiabatic shear band development in 316L stainless steel fabricated by cold metal transfer wire and arc additive manufacturing process. When as-built 316L samples subjected to dynamic compression ranging from 4400 s−1 to 6500 s−1, the flow stress increases with elevating strain rates coupled with forward strain showing a positive strain rate sensitivity. The strain hardening rate experiences an up-turn trend followed by a decrease due to the adiabatic thermal softening effect during ASB development. During dynamic loading, two separate ASBs at angles of ± 50° with respect to the loading axis were developed in a manner which is consistent with previous stimulation on strain and temperature distribution in textured fcc crystals. Typical textures of subgrains in ASBs are mainly dominant B/B‾ texture components, as well as A, A‾, A1, A2, C supplements, which means that subgrains in ASB mainly have [110] and [1‾1‾0] orientations along shear direction and (11‾2) and (1‾12‾) planes on shear planes. Differences in texture between front and rear parts of ASBs at different stages mean ASBs propagate in a dynamic way. Formation of fine subgrains with typical texture in ASB could be the circle process of twinning cutting and following dynamic recrystallization. This mechanism could be another important mechanism for subgrain refinement more than previous illustrated evolution of a dislocation cell. Following ASBs developing completely the dynamic fracture with brittle and ductile features occurs.