低温对TC4脉冲激光焊接接头组织和性能的影响

Effect of Low Temperature on the Microstructure and Mechanical Properties of Pulsed Nd∶YAG Laser Welding for TC4 Titanium Sheet

在-120~25℃温度范围内对TC4钛合金薄板脉冲激光焊接接头进行了拉伸试验,并对拉伸断裂后的显微组织进行了观察,研究了低温对TC4钛合金脉冲激光焊接接头组织和力学性能的影响。试验结果表明:随着温度的降低,TC4钛合金脉冲激光焊接接头的显微组织并未出现明显变化,拉伸强度升高而延伸率下降,呈延性断裂模式。在低温拉伸过程中,TC4钛合金脉冲激光焊接接头母材区域的α相中有滑移带形成,预示变形机制仍然是位错滑移机制。

To study the influence of low temperature on the microstructure and mechanical properties of pulsed Nd：YAG laser welded TC4 alloy sheets, the tensile tests at the temperatures ranging from -120℃ to 25℃ were carried out, and the specimens after tensile fracture were examined by scanning electron microscopy. Experimental results show that the microstructure of pulsed laser welded TC4 joint varies little under the low temperature. With the decrease of temperature, the tensile strength and ductility of pulsed laser welded TC4 joint increases and decreases, respectively. The mode of failure for pulsed laser welded TC4 joints is ductile with microvoid coalescence under low temperature conditions. In addition, the slip bands are observed in the a phase of base metal for pulsed laser welded TC4 joints during low temperature tensile process, indicating that the deformation mechanism is still the dislocation slip.