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采用高功率碟片激光器焊接8mm厚TC4钛合金,研究了激光焊接接头的显微组织和力学性能。结果表明,焊缝组织为晶界明显的粗大原始β柱状晶,晶内为针状马氏体,随着激光功率的增加,马氏体分布更加密集;近焊缝侧的热影响区组织为残余α相+针状马氏体,近母材侧的热影响区只发生α相向β相转变。焊接接头的显微硬度从母材到焊缝呈增加趋势,至焊缝处达到最高,不同功率下的焊缝显微硬度相当;8mm厚TC4钛合金在速度为2.7m/min,7.3~7.9kW高功率工艺参数下可获得质量良好的焊缝,焊接接头的抗拉强度、延伸率与母材相当,断裂在母材;在速度为2.7m/min,7.0kW低功率工艺参数下,焊缝有气孔倾向,焊接接头的延伸率只有母材的24%,断裂在焊缝。断在母材和焊缝的断口都呈韧窝形貌,断在焊缝的断口韧窝数目更少。
High-power disc laser welding 8mm thick TC4 titanium alloy, laser welded joints of the microstructure and mechanical properties. The results show that the weld microstructure is coarse primary β columnar grain with grain boundaries, and the microstructure is acicular martensite. With the increase of laser power, the martensite distribution is more intensive. The heat affected zone near the weld joint is Residual α phase + acicular martensite, near the parent material side of the heat-affected zone only α-phase β-phase transition. The microhardness of the welded joints increased from the base metal to the weld, reaching the highest at the weld, and the microhardness of the weld at different power was quite high. The 8mm thick TC4 titanium alloy was found to be stable at speeds of 2.7m / min and 7.3 ~ 7.9 kW high-power process parameters to obtain good quality weld, the tensile strength of the welded joints, elongation and the base metal equivalent fracture in the base metal; at a speed of 2.7m / min, 7.0kW low-power process parameters, welding There is a tendency of stomatal cracks, the elongation of the welded joint is only 24% of the base metal, fracture in the weld. Broken off in the base metal and weld fracture showed a dimple morphology, broken in the weld fracture dimples less number.