钎焊TA2/Q235用Zr-Ti-Ni-Cu非晶钎料研究

Study of Zr-Ti-Ni-Cu Amorphous Brazing Fillers Applied to Brazing Titanium TA2 and Q235 Steel

摘要: 本文针对钎焊温度高于882.5℃发生α-Ti向β-Ti相变，组织粗化，性能降低问题，采用正交试验优化钎料成分，得到二种成分熔点较低的Zr-Ti-Ni-Cu非晶钎料。利用快速冷凝设备制备钎料箔，实施对TA2/Q235的高频感应钎焊。结果表明，采用正交试验优化出的非晶钎料为Zr₅₂Ti₂₂Ni₁₈Cu₈和Zr₅₂Ti₂₄Ni₁₆Cu₈，钎料完全熔化的温度低于800℃，满足TA2钛不发生相变的钎接温度要求。钎接接头由钎缝区、钎缝与钛基材反应层及钎缝与钢基材结合层三部分组成。钎缝为方向性较强的粗大的Ti(Fe、Zr)固溶体枝晶，与TA2母材间存在反应层，与钢的结合区为Fe、C、Ti形成的亚稳态化合物组织。在钎接温度800℃，加热电流25 A，加热时间15 s，保温时间15 s条件下，获得的钎接接头剪切强度最高达到149 MPa。

Abstract: When brazing temperature is higher than 882.5˚C, titanium TA2 translates from α phase to β phase, whose microstructure is coarsened and the joint properties is decreased. For this issue, the compositions of brazing fillers were optimized by using orthogonal experiment and two kinds of Zr-Ti-Ni-Cu amorphous brazing fillers with lower melting temperatures were obtained in this paper. Filler foils were prepared by using rapid solidification apparatus and high frequency induction brazing of TA2 and Q235 were conducted. The results show that, amorphous brazing fillers Zr₅₂Ti₂₂Ni₁₈Cu₈ and Zr₅₂Ti₂₄Ni₁₆Cu₈ optimized by using orthogonal experiment, whose fully melting temperature is lower than 800˚C, totally satisfying the brazing temperature requirement that no phase transformation of TA2 occurs. The brazing joint is consisted of three parts: the brazing zone, the reaction layer of brazing seam and base metal TA2, and the bonding layer of brazing seam and base metal Q235. The microstructures of brazing seam are coarse Ti(Fe, Zr) solid solution dendrites with stronger orientation. Reaction layer is existed between brazing seam and base metal TA2, and the microstructures of the bonding layer of brazing seam and base metal Q235 are metastable compounds formed by Fe, C, Ti. When brazing parameters are temperature 800˚C, heating current 25 A, heating time 15 s and holding time 15 s, the shear strength of the joint obtained is up to 149 MPa.