复合金属材料激光焊接后热处理对焊缝脆性的改性研究

Study on modification of weld brittleness by heat treatment after laser welding of composite metal materials

  • 摘要: 激光焊接的高冷却速率易形成硬脆的粗大柱状晶粒,而后续热处理能促进位错重排及碳化物弥散析出,从而细化晶粒、降低内应力,提升焊缝的塑性和断裂韧性,但是对脆性有一定影响。因此,开展复合金属材料激光焊接后热处理对焊缝脆性的改性研究。选取铝合金作为复合金属材料焊接的母材,在焊条辅助下通过激光焊接技术实现焊接。设计三种不同焊后热处理工艺改性焊缝,检测各个工艺处理后焊缝的SEM图像。调整固溶保温时长,分析各工艺改性后焊缝力学性能、塑性、韧性的变化,以此分析出焊缝脆性特性。试验结果显示:热处理工艺2能显著降低焊缝脆性,提高韧性与延性;随固溶保温时间增加,晶粒增大导致力学性能下降,但工艺2处理后的焊缝力学性能更佳,固溶保温处理初期增强焊缝韧性,过长则下降,热处理工艺2能够降低焊缝的脆性实现焊缝改性。

     

    Abstract: The high cooling rate of laser welding can easily form hard and brittle coarse columnar grains, and subsequent heat treatment can promote dislocation rearrangement and carbide dispersion precipitation, thereby refining grains, reducing internal stress, and improving the plasticity and fracture toughness of the weld. Therefore, research is being conducted on the modification of weld brittleness through post laser heat treatment of composite metal materials. Selecting aluminum alloy as the base material for welding composite metal materials, welding is achieved through laser welding technology with the assistance of welding rods. Design three different post weld heat treatment processes to modify the weld seam, and test the SEM images of the weld seam after each process treatment. Adjust the duration of solid solution insulation and analyze the changes in the mechanical properties, plasticity, and toughness of the weld after various process modifications, in order to analyze the brittle characteristics of the weld. The experimental results show that heat treatment process 2 can significantly reduce weld brittleness, improve toughness and ductility; As the solid solution insulation time increases, the grain size increases, leading to a decrease in mechanical properties. However, the mechanical properties of the weld after process 2 treatment are better. The initial stage of solid solution insulation treatment enhances the toughness of the weld, and if it is too long, it decreases. Heat treatment process 2 can reduce the brittleness of the weld and achieve weld modification.

     

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