An original way for producing a 2.5 GPa strength ductile steel by rolling of martensite

TL;DR

This study presents a novel graded steel with a martensite core and bainite surface, achieving 2.5 GPa strength and ductility through partial decarburization and cold rolling, supported by a mechanical model.

Contribution

It introduces a new graded steel design and demonstrates its high strength and ductility via cold rolling, with a predictive mechanical model.

Findings

Achieved 2.5 GPa strength in graded steel

Cold rolled up to strain of 1.5 without cracks

Mechanical model explains ductility and stress state

Abstract

A compositionally-graded steel composed of martensite with 0.4%C on the centre and bainite with 0.1%C on the surface was manufactured by partial decarburization. It is reported that the as quenched material can be cold rolled up to an equivalent strain of 1.5 without cracks. The mechanical properties of the cold-rolled material exhibits up to 2.5 GPa strength and ductility. A simple mechanical model is developed to predict the stress state after rolling of the graded structure explaining the good ductility of the present high strength materials.