A quantitative investigation of the effect of Mn segregation on microstructural properties of quenching and partitioning steels

Quenching and partitioning (Q&P) process of a 0.3C-1.3Si-3.2Mn (wt%) steel with Mn segregation is studied experimentally and theoretically. During initial quenching a higher fraction of martensite forms in Mn-poor regions compared to Mn-rich regions. In the partitioning process, austenite in Mn-poor regions is surrounded with a higher fraction of martensite than austenite in Mn-rich regions and therefore receives a larger amount of carbon. When carbon partitioning is not sufficient to stabilize austenite, a higher fraction of martensite forms, during final quenching, in Mn-poor regions. Lowering the quenching temperature in the Q&P process reduces inhomogeneity in the distribution of phases.