ZnAl、AlSi(X)钎料钎焊铝/钢的接头耐腐蚀性研究

Study on the corrosion resistance of aluminum/steel joints brazed by ZnAl and AlSi(X) filler metal

采用扫描电镜、能谱分析及电化学腐蚀、盐雾腐蚀和力学性能测试等实验分析手段研究ZnAl2、AlSi12和AlSiNi钎料的铝/钢钎焊接头耐腐蚀性。实验表明,母材和钎缝耐腐蚀性由强至弱依次是:Q235钢、3003铝合金、AlSiNi钎缝、AlSi12钎缝、ZnAl2钎缝,钎缝金属易被腐蚀;经过240 h的盐雾腐蚀实验,AlSiNi接头抗拉强度降低27%,耐腐蚀性最强,Ni元素有效提高了AlSi钎料的耐腐蚀性,ZnAl2接头抗拉强度衰减达92%,耐腐蚀性最差;ZnAl2接头中残留的立体"花状"锌铝相表明钎缝中的Zn相会优先被腐蚀;AlSiNi、AlSi12接头中的腐蚀优先产生于母材钢/钎缝界面处,钎缝一侧的α-Al相优先被腐蚀。

The corrosion resistance of aluminum/steel joints brazed by ZnAl2,AlSi12 and AlSiNi filler metals were analyzed by means of SEM,EDS,electrochemical corrosion test,salt spray corrosion test and mechanical property test.Experiments show that the corrosion resistance from strong to weak are Q235 steel,3003 aluminum alloy,AlSiNi,AlSi12 and ZnAl2;brazing seam metal is more susceptible to corrosion.After 240 hours'salt spray corrosion test,ZnAl2 joints'tensile strength decreased by 92%,showed the worst corrosion-resistance;AlSiNi joints'tensile strength decreased by 27%,showed the best corrosion-resistance,Ni element could effectively improve the corrosion resistance of AlSi filler metal.The corrosion in AlSiNi and AlSi12 brazing joints preferentially occured at the interface of steel and brazing seam,theα-Al phase was firstly corroded.The Zn phase in ZnAl2 brazing joints was firstly corroded.