Abstract
Dual-phase structure formation in the intercritical annealing method is strongly affected by the cooling stage. Role of the cooling stage consists of
1) carbon enrichment into the untransformed austenite,
2) avoidance of pearlite formation, and
3) martensite and retained austenite formation.
Significance of a two-stage cooling can be explained on the above basis.
Employment of a rapid heating and a short-time intercritical holding produces a dual-phase steel having both a high bake-hardening and a high work-hardening characteristics. This phenomenon is supposedly related to a transient state of solute carbon partitioning in the intercritical temperature range.
