AA3003铝合金散热器的开裂失效分析  

Cracking failure analysis of AA3003 aluminum alloy radiator

作　　者：金林奎 郭联金[3] 欧海龙 黄持伟 阮育煌 

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 [3]东莞职业技术学院,广东东莞523808 [4]东莞市奕东电子有限公司,广东东莞523808

出　　处：《金属热处理》2018年第1期236-240,共5页Heat Treatment of Metals

基　　金：广东省东莞市产学研合作项目(201550910500294)

摘　　要：采用火花放电直读光谱仪、数显维氏硬度计及光学显微镜,对AA3003铝合金散热器总成开裂失效件的化学成分、表面硬度及显微组织进行理化检测和分析。检测结果表明,该失效件开裂形成的主要原因是由于焊缝部位焊后未进行退火处理,焊缝保留长条状共晶硅的铸态组织,使得焊缝部位强度降低,脆性增大。焊缝部位未焊足,焊接拘束应力未消除,在循环冷却液的腐蚀和冲击下,未焊足的焊缝间隙产生缝隙腐蚀,最终形成应力腐蚀开裂。与此同时,散热器总成开裂失效件还存在早期腐蚀的失效形式。腐蚀失效的原因是由于循环冷却液长时期未更换,冷却液的酸碱值提高,活性离子增多,造成零件表面大面积腐蚀。插件部位表层存在拉应力,造成表面应力腐蚀开裂的穿晶裂纹。主片部位组织中沿晶分布较多量的夹杂相,降低材料的耐腐蚀性能,因而导致表面沿晶腐蚀和腐蚀凹坑。The chemical composition,surface hardness and microstructure of AA3003 aluminum alloy radiator assembly with cracking failure were analyzed by means of physical and chemical tests using spark-discharge direct reading spectrometer,digital Vickers hardness tester and optical microscope. The test results show that the main reason for the cracking failure is that the weld seam does not undergo annealing after welding,and the weld seam retains the as-cast structure of the strip eutectic silicon,so that the strength of the weld seam decreases and the brittleness increases. Weld seam of the part is not filled enough,and the restraining stress is not eliminated. The weld seam corrosion happens under the action of corrosion and impact by the circulating coolant,and finally form the stress corrosion cracking. At the same time,the heater assembly with cracking failure also exists early corrosion. Corrosion failure is due to the p H value of the coolant increases during long-term circulating,resulting in the increase of the active ions,and severe corrosion of large area. The residual tensile stress on the surface of the plug-in part results in transgranular cracks in the stress corrosion cracked surface. The larger amount of inclusions distributed at the grain boundaries of the main part reduces the corrosion resistance of the material,resulting in grain boundaries corrosion and corrosion pits on surface of the radiator.

关 键 词：焊接加工 拘束应力 缝隙腐蚀 沿晶腐蚀 穿晶裂纹 

分 类 号：TG147[一般工业技术—材料科学与工程]