采用Gleeble-1500 热模拟试验机对6063铝合金进行热塑性实验, 确定了合金的脆性温度区间, 并用 SEM、EDS 等测试手段分析热裂纹的产生原因。研究结果表明, 综合Rm-T曲线和Z-T曲线可得到6063铝合金母材的脆性温度区间为460～620 ℃, 表明其具有较高的焊接热裂纹倾向。热输入量增大会使材料热塑性表现为先减小再增大的变化趋势, 热输入3.0 kJ/cm时试样的热塑性达到最低。热输入2.5 kJ/cm下, 在焊缝中没有观察到热裂纹; 热输入增大至3.5 kJ/cm, 试样的焊接热塑性明显增加, 呈现出朝焊缝中心发生纵向开裂的现象; 热输入3.0 kJ/cm下, 裂纹依然表现为从焊缝中心往纵向延伸开裂, 同时在母材的部分区域中形成许多断续分布的微坑。

The thermoplastic test of 6063 aluminum alloy was carried out by Gleeble-1500 thermal simulator. The brittle temperature range of the alloy was determined, and the causes of hot cracks were analyzed by SEM, EDS, etc. The results show that the comprehensive Rm-T curve and Z-T curve can obtain the brittle temperature range of 6063 aluminum alloy base material of 460～620 ℃, indicating that it has a high tendency to weld hot crack. The increase in heat input will cause the thermoplastic properties of the material to first decrease and then increase, and the thermoplasticity of the sample will be the lowest when the heat input is 3.0 kJ/cm. At the heat input of 2.5 kJ/cm, no hot crack was observed in the weld; the heat input increased to 3.5 kJ/cm, and the weld thermoplasticity of the sample increased significantly, showing a phenomenon of longitudinal cracking toward the center of the weld; heat input at 3.0 kJ/cm, the crack still appears to be cracked from the center of the weld to the longitudinal direction, and a plurality of intermittently distributed micro-pits are formed in a part of the base metal.