高牌号硅钢同材和异材激光−电弧复合焊接头组织及力学性能

Microstructure and mechanical properties of same-material and dissimilar laser-arc hybrid welded joints of high grade silicon steel

  • 摘要:
    目的 旨在研究常化态无取向高牌号硅钢V19合金同材和异材(Q235A)激光−电弧复合焊接头组织与性能,为高牌号硅钢激光焊及轧制工艺的制定提供指导依据。
    方法 利用电子背散射衍射、扫描电镜、拉伸试验等手段对比了焊接接头的微观组织及力学性能。
    结果 结果表明,同材焊和异材焊接头微观组织存在明显差异,其中,同材焊焊缝微观组织主要由铁素体柱状晶组成,异材焊焊缝由铁素体和珠光体组成。同材焊和异材焊V19合金侧热影响区受焊接热输入影响较小,组织形貌与母材基本保持一致,异材焊Q235A侧热影响区受焊接热输入不同而形成3个区域,分别为粗晶区、细晶区和组织不均匀区。同材焊和异材焊焊缝硬度均高于热影响区,但异材焊焊缝硬度分布更稳定。同材焊接头抗拉强度较异材焊提升9.3%,但均匀塑性变形能力低于异材焊。同材焊拉伸断裂模式为解理穿晶断裂,异材焊为韧性断裂。
    结论 Q235A与V19异材焊接头展现出优异的强塑性匹配,而V19同材焊焊缝粗大的柱状晶组织会降低塑性,并影响力学性能稳定性。

     

    Abstract: Objective The aim is to investigate the microstructure and performance of normalizing non-oriented high grade silicon steel V19 alloy of same-material and dissimilar (Q235A) laser-arc hybrid welded joint to provide guidance for formulating laser welding and rolling process for high grade silicon steel. Methods The microstructure and mechanical properties of welded joints are analyzed and compared using techniques such as electron backscatter diffraction, scanning electron micrcscope and tensile testing. Results The results show that obvious microstructure differences are found between the same-material and dissimilar welded joints. The weld of same-material welding is mainly composed of ferrite columnar crystal, while the weld of dissimilar joint is composed of ferrite and pearlite. The microstructure of heat affected zone on the V19 side of same-material and dissimilar welding is less affected by heat input and basically consistent with the base metal. The heat affected zone on the Q235A side of dissimilar welding can be divided into three kinds of zone, such as coarse grain area, fine grain area and microstructure non-uniform area, due to different heat input. The hardness of the welds is higher than that of the heat affected zone for the same-material and dissimilar welding. More stable hardness distribution on the weld is found for dissimilar welding. The tensile strength of the same-material welded joints is 9.3% higher than that of the dissimilar welded joints, but the dissimilar welded joints have better uniform plastic deformation ability than same-material welded joints. The tensile fracture mode of the same-material welded joints is cleavage transgranular fracture, while the dissimilar welded joint is ductile fracture. Conclusion The dissimilar welded joints between Q235A and V19 exhibit an excellent strength-plasticity matching, whereas the welds of V19 same-material welding characterized by coarse columnar grain structure reduces plasticity and affects the stability of mechanical properties.

     

/

返回文章
返回