Changes in mechanical properties of dual-phase steel due to post-welded microstructure and loading geometry

Since the early 2000's there has been increasing adoption of dual-phase steels for automotive manufacture. Dual-phase steels have a multiphase microstructure containing ferrite martensite and sometimes bainite, which is achieved through complex processing that often requires a high alloy content. This combination of a multiphase microstructure containing metastable phases and a heavily alloyed chemistry can cause a high degree of heterogeneity in the properties of welded joints. This paper explores the literature of both the metallurgy reactions responsible for the post-welded properties and the effect that these properties have on three linear welding techniques used in the automotive sector: laser welding, gas metal arc welding, and HF tube welding. Finally welding parameters and joint designs are suggested to optimize post-weld properties in DP steels. Copyright © 2013 ASM International® All rights reserved.