Dynamic mechanical properties of 316L stainless steel fabricated by an additive manufacturing process
Jie Chen, Haiyang Wei, Kuo Bao, Xianfeng Zhang, Yuanxun Cao, Yong Peng, Jian Kong, Kehong Wang
Abstract
The cold metal transfer (CMT) process, one of wire and arc additive manufacturing, was utilized to fabricate 316L stainless steel. As-built CMT 316L consists of austenitic coarse columnar grains aligned with depositing direction mainly and tiny areas of scattered ferrite (less than 5%) in dendrite. For comparison purposes, both as-built CMT 316L and annealed wrought 316L were dynamically characterized by Split-Hopkinson Pressure Bar. CMT 316L owns a nearly isotropic characteristic in dynamic compressions. Compared to wrought material, dynamic yield strength and flow stress for the CMT 316L are higher at small strains (below 10%) due to the special cellar structure in matrix but drop lower when the strain was larger than 10% for effect of twinning induced plasticity. Last but not least microstructural characterizations from a series of dynamic compressions of CMT 316L show that average twin thickness reaches maximum at strain rates about 1000–1500 s−1 and followed decreases with the increase of strain rates.