焊缝管液压成形技术及热影响区对成形的影响

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

结合研究成果讨论了焊缝材料性能对管材液压成形规律的影响，阐述了焊缝管液压成形的研究现状及发展趋势，以及亟待解决的关键问题。论述焊缝及热影响区材料性能的测定技术，包含焊缝及热影响区材料特性的有限元数值模拟模型的建立方法。结果表明：焊缝及热影响区的存在造成焊缝管的液压胀形特点及成形规律不同于无缝管。有缝管自由胀形后轮廓形状不对称；在距焊缝对称中心0°～15°之间的壁厚沿环向分布不均匀，在15～180°之间的壁厚基本上呈均匀分布，且壁厚值和与同种材料的无缝管在相同条件下胀形的壁厚值接近；焊缝材料比基体材料强度高，则极限胀形高度大。

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 nonuniform 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.