Microstructure of fibre laser welded joint of dual phase steel with bake hardening steel

Abstract

The fibre laser welding of dual phase DP600 steel and bake hardening BH220 steel were studied with a concentration on the microstructure of butt joints, but microhardness and tensile properties were also measured. The temperature peaks influenced the microstructure of the fusion zone and heat affected zone. The microstructure in the fusion zone was predominantly built of acicular ferrite with small areas of upper and lower bainite, and martensite. The similar microstructure was observed in the heat affected zone near DP600 steel. The microstructure in the heat affected zone near BH220 steel consisted mostly of coarse ferrite and acicular ferrite. The microhardness increased in the fusion zone and in the heat affected zone near DP600 steel, which was the consequence of martensite and bainite formation in these areas. The tensile strength of the fibre laser welded joints exceeded the strength of the BH220 steel base material with failure occurring in this steel.K e y w o r d s : dual phase steel, bake hardening steel, fibre laser welding, microstructure, microhardness

The Influence of Fiber Laser Pulse Processing on Coercivity and Nanohardness of Fe-3.2Si Grain-Oriented Electrical Steel in relation with its Surface Changes and Magnetic Domains Modifications

“…The commercially available laser scribing systems have been optimized typically for other applications and other materials such as scribing of crystalline Si, resistor trimming, or circuit repair [11,12]. In contrast to laser welding [13] or surface alloying by laser melt deposition [14], the laser * corresponding author; e-mail: vpuchy@saske.sk scribing may apply only a very low input power (e.g. up to 100 W), thus avoiding surface melting related deterioration of the treated material.…”