Effect of solution carbon and retained austenite films on the development of deformation structures of low-carbon lath martensite

Abstract

The deformation structure of low-carbon lath martensitic steels was analysed by transmission electron microscopy with Kikuchi pattern analysis. Retained austenite films on the martensite lath boundaries are transformed into high-carbon martensite films by light deformation. These high-carbon martensite films protect the martensite lath boundaries from reconstruction. Specific deformation structures of low-carbon lath martensite, such as kinked laths, irregularly bent lamellas and lamellar dislocation cells, were thus formed. Tempered lath martensite structures without retained austenite films easily disappeared by light deformation. The relationship between mechanical properties, such as the work-hardening ratio, and the development of the deformation structure was also clarified. © 2013 ISIJ.