Distribution behavior of inclusions in compact-strip-produced martensitic steel and its influence on mechanical properties

摘要

The distribution behavior of inclusions in martensitic steel produced by compact strip production process(CSP-MS)and its influence on mechanical properties were systematically investigated.The inclusions in the CSP-MS specimen are mainly composed of spherical Al_(2)O_(3)-CaO-CaS,MnS with high aspect ratio and small-sized TiN,whereas many coarse cuboidal TiN inclusions do exist in conventional martensitic steel(Con-MS).The high inclusion density of the CSP-MS specimen resulted in lower total elongation and impact toughness,and the MnS inclusions with high aspect ratio led to significantly stronger mechanical anisotropy than that for Con-MS specimen.The in-situ tensile results indicated that when the fracture direction is parallel to MnS direction,the microcracks induced by MnS inclusions tend to propagate into the matrix,leading to the formation of valley-like features,which significantly deteriorate the properties such as the total elongation and impact toughness.The microcracks caused by TiN inclusions are sharper than those caused by spherical Al_(2)O_(3)-CaO-CaS inclusions,and are easy to propagate into the matrix.This work is expected to guide the optimization of the mechanical properties of martensitic steels produced by CSP process and provide a theoretical basis for the CSP process design.