Research on process and mechanism of connection between Q235 steel and tin-based alloy at low temperature

Due to the existence of oxide layer on the surface of Q235 steel, it is difficult to directly achieve metallurgical bonding with tin-lead alloy, in order to solve this problem, this paper designed and successfully prepared steel surface activation liquid with the composition of 1 L distilled water, 130 g ZnCl₂, 90 g NH₄Cl, 5 mL 6501, and adding C₃H₆O₃ to adjust pH 3. The results show that the activated molten tin-lead alloy has a low wetting angle of 7.5° on the steel surface, which was then successfully plated on the steel surface by hot-dipping. The microstructural analysis of the plating-substrate interface and the thermodynamic calculation of the reaction can be found. The main structure of the interfacial reaction layer is α-Fe/FeSn₂/α-Pb + β-Sn.