Microstruttura e proprietà meccaniche di giunti saldati a fascio elettronico in acciaio DP600

Considering the safety standards required in the automotive industry and the need to reduce fuel consumption and greenhouse gas emissions, dual phase (DP) steels have gained their popularity thanks to their higher tensile strength in conjunction with superior formability if compared to the steel grades of similar yield strength. Such properties are related to their microstructure, which consists of soft ductile ferrite matrix, strengthened by hard martensitic phase. It is well known that welding processes play an important role in the automotive industry since they modify the mechanical, fatigue and metallurgical properties of the base material. A way to counteract the detrimental effects of welding is to reduce the width of heat affected zone (where mechanical properties generally decay) by using high power density processes. This work is aimed at evaluating the effects of Electron Beam Welding on metallurgical and mechanical properties of DP600 steel joints. Allotriomorphic ferrite, bainite and islands of martensite were detected in fusion zone. Results show that mechanical properties of the electron beam welded joints are comparable with those of parent metal both in terms of static strength and ductility.