Material analyses of high strength steels for automotive safety parts

Abstract

The martensitic high strength steels after hot stamping are currently widely used for safety automotive components characterized by a high strength-to-weight ratio and an increased resistance to impact. The durability of each parts is determined by dynamic strength of welded joints. The objective of presented analyses was study of weldability of martensitic steels and relevant degradation processes. The structural heterogeneity and diffusion processes in the AlSi coating have proved as a significant problem. The paper presents a selected results of revealed parameters, which influenced the phase transformation during welding and fracture behavior of heat affected zone. In order to avoid the identified harmful effect of redistribution of Al and Fe, the limited acceptable parameters of coating was proposed. The influence of austenitization process was estimated and the real intensity of discussed effects was evaluated by experimental welding.