(湖南大學 汽車車身先進設計制造國家重點實驗室，長沙 410082)
摘 要: 采用光纖激光器對1.4 mm厚的DC56D+ZF鍍鋅鋼和1.2 mm厚的6016鋁合金平板試件進行有無膠層加入的激光搭接焊和耐蝕性實驗，利用臥式金相顯微鏡、掃描電鏡、X射線衍射儀、微機控制電子萬能試驗機等分析膠層加入前后焊接接頭的金相組織、斷口形貌、界面元素、腐蝕速度、腐蝕產(chǎn)物形貌與成分以及接頭力學性能，探討膠層影響鋼/鋁焊接試樣耐腐蝕性能的作用機制。結果表明：激光功率1650 W，焊接速度35 mm/s，離焦量＋3.0 mm，Ar為保護氣體且流量為20 L/min的工藝條件下，加入膠層，焊接試樣正面焊縫均勻連續(xù)，無氣孔和裂紋等缺陷；膠層的加入改善了搭接焊中因間隙而產(chǎn)生的熱傳遞受阻現(xiàn)象，與未加膠層相比，橫截面金屬平板試件間隙減少，熔深值增大；膠層受激光作用分解形成氣體和固體殘留物，改變鋁合金表面高反射率狀況，加大鋁合金對激光能量的吸收，鋼/鋁熔融金屬冷卻后互相嵌入，與未加入膠層相比，鋼/鋁界面分界線不十分連續(xù)；激光焊接中加入膠層，焊接接頭抗剪強度與平均剪切力分別為41.45 MPa和1.04 kN，力學性能并沒有因為膠層的加入而減弱；同等腐蝕條件下，焊接試樣腐蝕方式為電偶腐蝕，腐蝕產(chǎn)物主要為Fe2O3、FeO(OH)、Fe6(OH)12CO3，與未加入膠層相比，焊接試樣腐蝕速度減慢，耐蝕性提高；由于膠層具有絕緣性，可以抑制陽極和陰極之間的電子交換，減緩電偶腐蝕，因此，膠層的加入明顯提高了鋼/鋁焊接試樣的耐腐蝕性能。
關鍵字: 鋼/鋁異種金屬；激光膠接焊；焊縫形貌；耐腐蝕性能
（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
