(哈爾濱工業(yè)大學(xué) 現(xiàn)代焊接生產(chǎn)技術(shù)國家重點(diǎn)實驗室，哈爾濱 150001)
摘 要: 通過在不銹鋼表面預(yù)涂釬劑層，采用鋁硅共晶釬料實現(xiàn)鋁合金/不銹鋼TIG熔釬焊連接，獲得具有熔焊與釬焊雙重性質(zhì)的對接接頭，運(yùn)用OM、SEM、EDS分析接頭的微觀組織及成分，通過拉伸實驗評定接頭的力學(xué)性能。結(jié)果表明：鋁母材局部熔化，與液態(tài)釬料混合后凝固形成焊縫，焊縫組織主要由α(Al)基體和在晶界析出的Al-Si共晶相組成；不銹鋼不發(fā)生熔化，液態(tài)釬料與不銹鋼在界面反應(yīng)形成不均勻分布的金屬間化合物層，最大厚度不超過10 μm，界面上部金屬間化合物較厚，呈鋸齒狀，主要相成分為α(τ5)-Al7.4Fe2Si；界面下部金屬間化合物較薄，呈細(xì)須狀，由α(τ5)-Al7.4Fe2Si+α(Al)混合相構(gòu)成；接頭的平均抗拉強(qiáng)度為90.6 MPa，焊縫/不銹鋼界面下部為連接的薄弱環(huán)節(jié)，成為斷裂的起始位置。
關(guān)鍵字: 異種金屬；鎢極氬弧熔釬焊；預(yù)涂釬劑層；界面反應(yīng)層；力學(xué)性能
（State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology,
Harbin 150001, China）
Abstract:Dissimilar metals TIG welding-brazing of aluminum alloy to stainless steel was conducted using Al-Si eutectic wire with precoating special flux layer on the steel surface. The microstructure characteristics of aluminum alloy/stainless steel butt joint were analyzed by OM, SEM and EDS, and the tensile strength of the joint was measured by instron-testing machine. The results show that the aluminum base material is melted and mixed with the liquid filler metal to form the welded seam, which consists of α(Al) matrix and Al-Si eutectic phases in the intergranular. The stainless steel is not melted and reacts with the melted metal to form nonuniform intermetallic compound (IMC) at the welded seam/steel interfacial layer, of which the thickness is less than 10 μm. At the upper part of the layer, the IMC is thick and presents serrated-shape and consists of α(τ5)-Al7.4Fe2Si phase, while at the lower part, the IMC is thinner than the upper part and presents thin whiskered-shape and consists of α(τ5)-Al7.4Fe2Si+α(Al) mixed phases. The average tensile strength of joints is 90.6 MPa and the fracture starts at the lower part of the welded seam/stainless steel interfacial layer, which is the weak bonding zone of the joint.
Key words: dissimilar metal; TIG welding-brazing; precoating flux layer; interfacial layer; mechanical property
