高强铝合金脉冲变极性等离子弧焊接头组织与性能

采用脉冲变极性等离子弧焊对厚度10 mm的7075铝合金进行焊接，利用光学显微镜、扫描电子显微镜、X射线衍射仪、万能拉伸试验机和显微硬度仪对焊缝的显微组织和焊接接头的力学性能进行了分析和测试，研究植入脉冲对焊接接头组织及力学性能的影响.结果表明，植入脉冲后焊接接头成形良好，由于高低频脉冲的周期性变化引起熔池液体强烈的搅拌作用，细化了焊缝的显微组织，强化相T相得到细化，提高了焊缝的抗拉强度和显微硬度，焊缝处的抗拉强度为397.9 MPa，约为母材强度的67.5%，比未植入脉冲时提高了5.13%，焊缝质量有所提高.

Microstructure and mechanical properties of pulse VPPA welded high-strength aluminum alloy joints

The 7075 aluminum alloy sheet with thickness of 10mm was welded by pulse VPPA vertical welding process, the microstructures and mechanical properties of welded joint were studied by means of optical microscope(OM), scanning electron microscope(SEM), X-ray diffraction(XRD), universal tensile testing machine and micro-hardness testing machine. The effect of pulse on microstructure and mechanical properties of welded joint were comparatively investigated. Experimental results indicated that the finally welded products exhibited an excellent appearance. Due to the enhanced stirring effect in weld pool induced by the periodicity variation of pulse current, the microstructure and the strengthening T phase of the weld were refined, the tensile strength and the hardness of the welded joint were increased. The tensile strength reached 397.9 MPa, which was nearly 67.5% of the parent metal, and it was increased by 5.13% than the weld without pulse treatment, the welding quality was also improved.