Effect of Microstructural Factors and Mechanical Properties on Axial Crash Fracture of High Strength Steel Sheets

Abstract

In the application of high strength steels to energy-absorbing parts of automobile, it is important to stably obtain high absorption energy by suppressing fracture in crash deformation. In this study, a new fracture resistance evaluation method simulating the axial crashing deformation in the press formed area was used to clarify the effects of mechanical properties and microstructure on the fracture behavior. High hole expansion ratio (λ) steel with tempered martensite and bainite suppressed both initiation and propagation of the crack in the pre-formed area. From these results, the fracture resistance was thought to improve by controlling microstructure for high λ.