AL6R01Z铝合金外壳粗加工开裂失效分析  

Gracking failure analysis on AL6R01Z aluminum alloy shell in rough machining

作　　者：金林奎 吴正环 程曦 黎肖辉 方曼婷 Jin Linkui;Wu Zhenghuan;Cheng Xi;Li Xiaohui;Fang Manting(Guangdong Dongguan Quality Supervision Testing Center,Dongguan 523808,China;National Mold Product Quality Supervision and Inspection Center,Dongguan 523808,China)

机构地区：[1]广东省东莞市质量监督检测中心,广东东莞523808 [2]国家模具产品质量监督检验中心,广东东莞523808

出　　处：《锻压技术》2023年第4期32-37,共6页Forging & Stamping Technology

基　　金：广东省东莞市产学研合作项目(202150901500294)。

摘　　要：针对铝合金外壳粗加工过程中产生的开裂问题,采用金相显微镜、扫描电镜及能谱仪对外壳件开裂样品进行检测和分析。铝合金外壳精锻后,锻件表面显示出变形不均匀的锻造流线,锻件圆角部位的变形量最大,在精锻件样品表层存在弯曲变形的表面裂纹,推测为锻造折叠裂纹。铝合金外壳粗加工后,沿变形量最大的外壳圆角底部产生开裂,开裂件样品的表面裂纹扩展特征呈弯曲圆弧状,裂纹间隙存在纤维组织以及酸洗残留腐蚀凹坑,由此推测表面裂纹属于热加工锻造裂纹。并且,在裂纹尾部存在塑性不足造成的龙爪状挤压裂纹,表明样品表层存在温度偏低现象。能谱测试结果表明,裂纹间隙的氧含量高达23.35%,说明该表面裂纹经过高温氧化,进一步验证了表面裂纹是在锻造过程中产生的。分析得出造成铝合金外壳开裂的主要原因为:锻造过程中的锻件表层温度低、材料塑性不足,导致锻件表层与次表层变形不一致,从而在锻件变形量最大的圆角底部产生锻造折叠裂纹,而锻造过程的持续变形使得表面裂纹重新闭合,但由于粗加工过程中发生应力释放,导致表面裂纹再次张开。For the cracking problem of aluminum alloy shell during rough machining,the cracking shell sample was detected and analyzed by metallographic microscope,scanning electron microscope and energy dispersive spectrometer.After precision forging of aluminum alloy shell,the surface of forgings shows the forging streamline with uneven deformation,and the deformation amount in the fillet part of forgings was the largest.And,there is a surface crack of bending deformation on the surface layer of precision forging sample,which is supposed to be a folded forging crack.Then after rough machining of aluminum alloy shell,cracks occurr along the rounded bottom of shell with the largest deformation amount.Furthermore,the surface crack growth characteristics of cracked sample are curved arcs,and there are fiber organization and pickling residual corrosion pits in the crack,so it is inferred that the surface cracks belong to hot forging cracks.In addition,there are claw-shaped extrusion cracks at end of the cracks caused by insufficient plasticity,indicating that the temperature of sample surface is low.The results of energy spectrum test show that the oxygen content in the crack is as high as 23.35%,indicating that the surface crack is oxidized at high temperature,and it is further verified that the surface crack is generated during the forging process.The main reasons for the cracking of aluminum alloy shell are obtained by the analysis that the surface temperature of forgings during the forging process is law and the plasticity of material is insufficient,the deformations in the surface and subsurface of forgings are inconsistent,the forging folding crack appears at the counded bottom with the largest deformation amount of forgings,and the surface cracks reclose due to the continuous deformation during the forging process,but the surface crack reopens due to the stress release during the rough machining process.

关 键 词：精锻 粗加工 锻造流线 腐蚀凹坑 折叠裂纹 挤压裂纹 

分 类 号：TG147[一般工业技术—材料科学与工程]