Al-12.7Si-0.7Mg合金焊接热裂纹倾向性研究  

Research on hot cracking susceptibility of Al-12.7Si-0.7Mg alloy

作　　者：王东[1] 何长树[1] 王浩[1] 刘建[2] 赵骧[1] 左良[1] 

机构地区：[1]东北大学材料各向异性与织构教育部重点实验室,沈阳110819 [2]南车青岛四方机车车辆股份有限公司,青岛266111

出　　处：《材料与冶金学报》2014年第4期266-271,共6页Journal of Materials and Metallurgy

基　　金：国家科技支撑计划项目(节约型高硅变形铝硅合金生产工艺开发与示范;2009BAE80B01);国家科技支撑计划项目(高速列车关键材料及部件可靠性;2009BAG12A07-B02);长江学者和创新团队发展计划项目(IRT0713)

摘　　要：在不填丝的情况下,采用自动TIG焊对Al-12.7Si-0.7Mg合金热挤压型材进行鱼骨状裂纹试验.通过目测、金相观察、EDS分析、显微硬度测定等方法研究了该合金的焊接热裂纹倾向性及焊接接头显微组织与硬度分布.结果表明:焊缝表面与内部均未发现裂纹,合金焊接热裂纹倾向性低.焊缝区是母材在焊接热作用下熔化后激冷形成的铸态组织,主要由α-Al、Al-Si共晶相以及少量Mg2Si、含Fe相等金属间化合物构成。经T6处理后,焊缝区中呈密集纤维状的共晶硅粒状化.显微硬度测试结果显示焊态接头焊缝区硬度最高,熔合区急剧下降,在热影响区达到最低,经T6处理后,接头各区显微硬度整体提升,且波动较小.Fish -bone cracking test was carried out on the hot extruded Al - 12. 7Si -0. 7Mg alloy by using automatic TIG welding method without filler metal, The hot cracking susceptibility of the alloy and microstructures as well as micro- hardness distribution of the welded joint were studied by visual inspection, optical microscopy, EDS spectra analysis and micro - hardness test. The results showed that there is no cracking found on surface or in interior of the welded joint, the hot cracking susceptibility is low. The weld zone is a typical casting structure formed during the weld solidification affected by the welding heat input. The weld zone is mairdy composed of α- Al, Al - Si eutectic phase and a few ofintermetallics phases （Mg2Si, Fe - containing phase） precipitated in the interdendritic regions. Treated by T6, the fibrous eutectic Si in the weld zone is spheroidized. Distribution of the micro - hardness showed that the hardness of as - welded joint gets maximum values in the weld zone, drops rapidly in the fusion zone and reaches minimum values at the heat affected zone. Treated by T6, hardness on the joints increases entirely and stably.

关 键 词：Al-12.7Si-0.7Mg合金 TIG焊 焊接热裂纹倾向性 显微组织 

分 类 号：TG457.14[金属学及工艺—焊接]