ZL205A大厚板铝合金TIG堆焊组织与性能研究  

Microstructure and Properties of Large Thick Plate ZL205A Aluminum Alloy by TIG Bead Welding

作　　者：刘浩 温泉 吴雪猛 陈潜 赵静[1] 向辉耀 LIU Hao;WEN Quan;WU Xue-meng;CHEN Qian;ZHAO Jing;XIANG Hui-yao(State-owned Sida Machinery Manufacturing Company,Shaanxi Xianyang 712203,China)

机构地区：[1]国营四达机械制造公司,陕西咸阳712203

出　　处：《精密成形工程》2023年第7期136-145,共10页Journal of Netshape Forming Engineering

摘　　要：目的解决壁厚25 mm的ZL205A铸造铝合金在多层多道TIG焊过程中接头易出现气孔和虚焊等问题,进而实现大厚板ZL205A的高质量焊接。方法采用TIG堆焊方法对25 mm厚的ZL205A进行焊接,研究不同层间焊接电流对接头组织和力学性能的影响。结果焊后接头焊核区存在明显的气孔缺陷,随层间焊接电流的增大,气孔缺陷数量和尺寸显著增加。焊接接头根据组织特征分为焊核区、熔合区、热影响区和母材区,其中焊核区晶粒尺寸最小,约为20μm,仅为母材晶粒尺寸的1/5左右。在焊核区晶界处弥散分布了大量Al2Cu、AlCu及少量Al12CuMn2颗粒相。随焊接电流的增大,接头拉伸强度及伸长率呈现先增大后减小的趋势,其最大拉伸强度为母材强度的94%,最大伸长率仅为母材伸长率的41.72%。在最优焊接电流下,接头拉伸断裂位置为母材处和焊缝处,气孔缺陷是导致焊缝断裂的主要原因,而母材断裂的主要原因为晶界间存在较多脆硬性AlCu/颗粒相。结论采用TIG多层多道的焊接方法通过控制不同层间电流可以实现25 mm厚ZL205A的高强度焊接。The work aims to solve the problem of air hole and insufficient welding caused by multi-layer and multi-pass welding in TIG welding process of ZL205A cast aluminum alloy with wall thickness of 25 mm,and realize high quality welding of large thick plate ZL205A.25 mm thick ZL205A was welded by TIG bead welding,and the effect of interlayer welding current on the microstructure and mechanical properties of the joint was studied.The results showed that there were obvious air hole defects in the welding nugget zone.With the increase of the welding current,the number and size of air holes increased.Welded joints were divided into welding nugget zone,fusion zone,heat affected zone and base metal zone according to their microstructure characteristics.The minimum grain size in the welding nugget zone was the smallest,which was about 20μm,and about 1/5 of the grain size of the base metal.A large number of Al2Cu,AlCu and a small number of Al12CuMn2 particulate phases were widely distributed in the welding nugget zone.With the increase of the welding current,the tensile strength and elongation of the joints increased first and then decreased.Its maximum tensile strength and elongation were 94%and 41.72%of the base metal.When the welding current was optimal,the tensile fracture of the joint was located at the base metal fracture and the weld seam fracture.Air hole defects was the main cause of weld fracture,while the main cause of base metal fracture was that there were many AlCu particulate phases between crystal boundaries.The high strength welding of 25 mm thick ZL205A can be realized by controlling the current between different layers with TIG multi-layer and multi-pass welding.

关 键 词：铸造铝合金 大厚板 焊接电流 多层多道 颗粒相 

分 类 号：TG146.21[一般工业技术—材料科学与工程]