Microstructure and properties of X100 large-deformability pipeline steel based on heating on-line partitioning

Abstract

It is often assumed that high strength and good plasticity cannot be obtained at the same time. However, a kind of X100 pipeline steel with a multiphase structure of bainite and fine M/A constituent has not only high strength and toughness but also excellent plasticity. In this paper, Heating on-line partitioning (HOP) was performed on a type of X100 pipeline steel to achieve the multiphase structure. Carbon atoms diffuse from bainite to austenite during the HOP process, improving the stability of austenite and increasing the volume fraction of retained austenite. Meanwhile, bainite laths widen and dislocation density drops, increasing the plasticity. On the other hand, carbides precipitation and the formation of martensite provide the steel with high strength.