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ΔK<18.63 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。
The mechanical properties of 4 mm thick A6N01-T5 aluminum alloy plate joints obatained by laser-single wire pulse MIG hybrid welding and MIG welding were compared by using microhardness and tensile properties tests. The fatigue properties and fracture behavior of laser -MIG hybrid welding joint were discussed by high cycle fatigue test, fatigue crack growth rate test and fatigue fracture analysis. The results show that compared with that of base metal, the loss of strength exists in both laser-MIG welding joint and MIG welding joint, and the loss degree of MIG joint is worse. With the increase of stress amplitude, the fatigue life of hybrid welding joint decreases. Meanwhile, under the same stress amplitude, the life data are scattered. Under 50% survival rate, the fatigue strength of A6N01 alloy laser hybrid welding joint is 104 MPa, which is about 88.9% of that of base metal （117 MPa）, The da/d N-△K curves of the base metal and hybrid welding joint intersect, and when △K〈18.63 MPa. m1/2, the crack growth rate of the joint slower than that of base metal, which can be considered safe. The fatigue crack of the hybrid welding joint is initiates at the machining defect, the crack source shows cleavage river pattern. No fatigue bands are found in the crack growth zone. There are dimples with different sizes and sharp tearing edges in the final fracture region, which shows a mixed fracture mode of quasi cleavage fracture and ductile fracture.
出处
《热加工工艺》
CSCD
北大核心
2017年第7期64-67,71,共5页
Hot Working Technology
