高速列车用A6N01-T5铝合金激光-MIG复合焊接头疲劳性能研究

发布时间：2018-09-15 19:38

【摘要】：采用显微硬度和拉伸性能测试对比了激光-单丝脉冲MIG复合焊和MIG焊接的4 mm厚A6N01-T5铝合金板接头的力学性能。通过高周疲劳测试、疲劳裂纹扩展速率试验以及疲劳断口分析,探讨了激光-MIG复合焊接头的疲劳性能和断裂行为。结果表明,与母材相比,复合焊接头和MIG焊接头焊后均发生强度损失现象,且MIG焊接头的损失程度更为严重。复合焊接头疲劳寿命随应力幅的增加而减小,且同一应力幅下,寿命分布具有分散性,50%存活率下A6N01铝合金复合焊接头的疲劳强度为104 MPa,为母材(117 MPa)的88.9%。A6N01铝合金母材和复合焊接头的da/d N-ΔK曲线存在交叉现象,当ΔK18.63 MPa·m~(1/2)时,焊缝的裂纹扩展速率慢于母材,认为可以安全可靠地进行服役。复合焊接头疲劳裂纹由加工缺陷处萌生,裂纹源区呈现类解理河流花样;裂纹稳定扩展区未发现疲劳条带;瞬断区存在大小不一的韧窝和较为尖锐的撕裂棱,呈现准解理断裂和韧性断裂的混合断裂形式。
[Abstract]:The mechanical properties of 4 mm thick A6N01-T5 aluminum alloy plate joints welded by laser-monofilament pulse MIG composite welding and MIG welding were compared by means of microhardness and tensile test. The fatigue properties and fracture behavior of laser-MIG composite welded joints were investigated by high cycle fatigue test, fatigue crack growth rate test and fatigue fracture analysis. The results show that, compared with the base metal, the strength loss of the composite welding joint and the MIG welding joint occurs after welding, and the loss degree of the MIG welding joint is more serious. The fatigue life of composite welded joints decreases with the increase of stress amplitude, and at the same stress amplitude, When the fatigue strength of A6N01 aluminum alloy composite welding joint is 104 MPa, as base metal (117 MPa) and the da/d N- 螖 K curve of composite welding joint has cross phenomena, when 螖 K 18.63 MPa m ~ (1 / 2), the fatigue strength of A6N01 aluminum alloy composite welding joint is 50% dispersed and the fatigue strength of 88.9%.A6N01 aluminum alloy base metal is 117 MPa. The crack growth rate of the weld is slower than that of the base metal, and it can be safely and reliably in service. The fatigue crack of the composite welding joint originates from the machining defect, and the crack source area presents cleavage river pattern; no fatigue band is found in the crack stable growth zone; there are dimples of different sizes and sharp tearing edges in the transient fracture zone. There are mixed fracture forms of quasi-cleavage and ductile fracture.
【作者单位】：四川工程职业技术学院;
【分类号】：TG407

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