Q-P process on steels with various carbon and chromium contents

Abstract

The Q-P process is an innovative process of heat treatment, which allows tensile strength above 2000 MPa with an elongation over 10% to be obtained. To achieve a suitable structure, appropriate alloying strategies and process parameters have to be used. The influence of carbon and chromium on the micro structure development and on mechanical properties was explored with four experimental steels. In addition to carbon levels in the range from 0.2 to 0.56% and chromium from 0.65 to 1.33%, these steels also contained manganese and silicon. Martensitic structures with a small fraction of ferrite and with retained austenite (RA) were achieved after thermomechanical treatment. The highest tensile strength of over 2300 MPa with an elongation above 10% was obtained in the steel with the carbon content of 0.56%. With a carbon content of 0.2% the martensite with higher ferrite fraction and RA was achieved. The tensile strength reached 1000 MPa with A5mm elongation above 30%.