Tailor-welded tube in hydroforming and influence of the heat affected zone on bulge forming

In this paper,the state-of-the-art research and future trends of tailor-welded tube in hydroforming are reviewed and the paramount problems in this aspect are proposed.Emphases are given to the up-to-date measuring techniques of the mechanical properties of the weld line and the HAZ and the skilful approach to create finite element simulation model including base material,the weld line and the HAZ.Based on some of the research results of the authors,the influence of the weld properties on tube hydroforming is discussed.The results show that(1) seamed tube can maintain an asymmetrical profile during the free hydraulic bulges(FHB),(2) a non-uniform thickness distribution within 0°~15°,a uniform thickness distribution within 15°~180° in circumferential direction away from the weld line are observed in the FHB of seamed tubes,which is similar to that observed in the FHB of seamless tube with the same specification and(3) a larger bulge height can be obtained when the weld metal has a higher strength than the base metal.