Nanostructure of a cold drawn tempered martensitic steel

TL;DR

This study uses 3D atom probe analysis to investigate how cold drawing affects the nanostructure of tempered martensitic steel, revealing early cementite decomposition and carbon atom diffusion mechanisms.

Contribution

It provides new insights into the nanostructural evolution and carbon atom behavior in tempered martensitic steel during cold deformation.

Findings

Cementite decomposes early during cold drawing.

Carbon atmospheres likely result from pipe diffusion along dislocations.

Decomposition is not driven by interfacial energy increase.

Abstract

The carbon atom distribution in a tempered martensitic steel processed by cold drawing was investigated with a three-dimensional atom probe. Data clearly show that cementite starts to decompose at the early stage of deformation. This indicates that the driving force of cementite decomposition during plastic deformation is not related to a strong increase of the interfacial energy. Carbon atmospheres were also analysed. They probably result from pipe diffusion of carbon atoms along dislocations pined by Fe3C carbides.