Strain rate behaviour of multi-phase and complex-phase steels for automotive applications

E Cadoni,N.K Singh,M.K Singha,N.K Gupta

doi:10.1051/epjconf/20122605003

Abstract

A combined study on the mechanical behaviour of multi-phase 800 high yield strength steel (MP800HY) and complex-phase 800 steel (CP800) is carried out under tensile loads in the strain rate range from 0.001s −1 to 750s −1 . Quasi-static (0.001s −1 ) tests are performed on electromechanical machine, whereas, medium (5s −1 and 25s −1 ) and high strain rate (250s −1 , 500s −1 and 750s −1 ) experiments are conducted on hydro-pneumatic machine (HPM) and modified Hopkinson bar (MHB) setup respectively. The thermal softening behaviors of the materials are investigated at quasi-static condition and the materials’ m -parameters of the existing Johnson-Cook model are imposed in authors’ previous work. Thereafter, the predicted flow stress by Johnson-Cook model has been compared with the experimental results.

Highlights

The requirement of lightweight and high strength materials in the automobile industry has motivated researchers to use different advanced high strength steels
Study of the mechanical behaviours of such materials at different loading rates is needed to design the auto-body structures for the maximum possible dissipation of crash energy
The material m-parameter of the existing Johnson-Cook model has been imposed in the previous work and the predicted flow stresses by this model are compared with the experimental results at different strain rates

Summary

Introduction

The requirement of lightweight and high strength materials in the automobile industry has motivated researchers to use different advanced high strength steels. The material m-parameter of the existing Johnson-Cook model has been imposed in the previous work and the predicted flow stresses by this model are compared with the experimental results at different strain rates. The stress-strain curves of different strain rates at room temperature are compared and the measured experimental results are presented in [5, 6].

Results

Conclusion