Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第24卷    第7期    总第184期    2014年7月

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文章编号:1004-0609(2014)07-1736-08
激光胶接焊镀锌钢/铝合金的显微组织与性能
周惦武,戴 婷,徐少华,刘金水

(湖南大学 汽车车身先进设计制造国家重点实验室,长沙 410082)

摘 要: 采用光纤激光器对1.4 mm厚的DC56D+ZF镀锌钢和1.2 mm厚的6016铝合金平板试件进行有无胶层加入的激光搭接焊和耐蚀性实验,利用卧式金相显微镜、扫描电镜、X射线衍射仪、微机控制电子万能试验机等分析胶层加入前后焊接接头的金相组织、断口形貌、界面元素、腐蚀速度、腐蚀产物形貌与成分以及接头力学性能,探讨胶层影响钢/铝焊接试样耐腐蚀性能的作用机制。结果表明:激光功率1650 W,焊接速度35 mm/s,离焦量+3.0 mm,Ar为保护气体且流量为20 L/min的工艺条件下,加入胶层,焊接试样正面焊缝均匀连续,无气孔和裂纹等缺陷;胶层的加入改善了搭接焊中因间隙而产生的热传递受阻现象,与未加胶层相比,横截面金属平板试件间隙减少,熔深值增大;胶层受激光作用分解形成气体和固体残留物,改变铝合金表面高反射率状况,加大铝合金对激光能量的吸收,钢/铝熔融金属冷却后互相嵌入,与未加入胶层相比,钢/铝界面分界线不十分连续;激光焊接中加入胶层,焊接接头抗剪强度与平均剪切力分别为41.45 MPa和1.04 kN,力学性能并没有因为胶层的加入而减弱;同等腐蚀条件下,焊接试样腐蚀方式为电偶腐蚀,腐蚀产物主要为Fe2O3、FeO(OH)、Fe6(OH)12CO3,与未加入胶层相比,焊接试样腐蚀速度减慢,耐蚀性提高;由于胶层具有绝缘性,可以抑制阳极和阴极之间的电子交换,减缓电偶腐蚀,因此,胶层的加入明显提高了钢/铝焊接试样的耐腐蚀性能。

 

关键字: 钢/铝异种金属;激光胶接焊;焊缝形貌;耐腐蚀性能

Microstructure and properties of galvanized steel/ aluminum alloy laser-adhesive hybrid bonding
ZHOU Dian-wu, DAI Ting, XU Shao-hua, LIU Jin-shui

State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,
Hunan University, Changsha 410082, China

Abstract:The fiber laser welding and corrosion resistance test with/without adhesive layer addition were carried out on the DC56D+ ZF galvanized steel with thickness of 1.4 mm and the 6016 aluminum alloy with thickness of 1.2 mm. By using optical microscopy, scanning electron microscopy, X-ray diffractometry and tensile test, the microstructure, fracture morphology, interface element distribution, corrosion rate, corrosion morphology, composition and mechanical properties of joints were studied, the effect of adhesive layer on the corrosion resistance of weld joint was also discussed. The results indicate that addition of adhesive can improve the block of heat transfer caused by the interstice of overlap welding and the feature of welding are uniformly continuous without pore or flaw at the welding process parameters as follows, such as laser power of 1650W,welding speed of 35mm/s, defocusing amount of +3.0 mm, Ar as the protection gas and flowing at the speed of 20 L/min. Comparing with the sample without adhesive layer, the interstice of metal plate specimen decreases and the penetration is deeper, the adhesive layer is decomposed into gas and solid residue, thus, the aluminum alloy surface with high reflectivity feature is changed, and the laser energy absorption of aluminum alloy increases, the molten metals of steel and aluminum embed into each other after cooling. Comparing with the sample without adhesive layer, the steel and aluminum interface boundary is not continuous. In laser weld bonding, the average shearing strength and average shearing force of steel/Al joint are 41.45 MPa and 1.04 kN. The mechanical properties are not weakened by the addition of adhesive layer. Under the same corrosion condition, galvanic corrosion of welding specimen is found and corrosion product are Fe2O3, FeO(OH) and Fe6(OH)12CO3. Comparing with the sample without adhesive layer, the corrosion rate of the sample with adhesive layer decreases, and the corrosion resistance properties are improved. Because the adhesive layer has electric resistance and insulation properties, it controls electron exchange between the anode and the cathode, reduces galvanic corrosion effect which improves corrosion resistance of steel and aluminum welded specimen with adhesive layer addition.

 

Key words: steel/Al alloy dissimilar metal; laser-adhesive hybrid bonding; weld appearance; corrosion resistance properties

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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