Optimizing strength-ductility synergy in lightweight steel via heterogeneous design: discontinuous fibrous ferrite
Qian Cheng, Bo Yang, Chao Zhang, Xue Chen, Wuli Su, Xiaochong Lü, Jianxiong Liang, Wenquan Cao, Chongxiang Huang
Abstract
Disperse ferrite is generally embedded in lightweight steel, yet exhibits decent performance, thereby prompting a question: can heterogeneous design optimize it? Here, two representative structures, featured with discontinuous fibrous and dispersed ferrite separately embedded in the austenite matrix, were constructed as examples to address the issue. A heterostructure with fibrous ferrite shows a remarkable product (49 GPa·%) of ultimate strength and total elongation, standing out among other lightweight steels. Superior strength-ductility synergy is primarily attributed to hetero-deformation-induced strengthening and hardening. Abundant hetero-interactions imparted by phase boundaries, dense slip bands in austenite and dislocation networks inside ferrite serve as underlying physical mechanisms.