On the Peeling Strength of Soldered Joint in Tin and Zinc Coated Steel

Abstract

The joint strength of metals is usually tested by various methods, tensile, shearing, peeling, bending, impact and so on, but it is considered risky to judge the joint strength from only one kind of testing, because each testing has a characteristic. An investigation of soldered joint strength was undertaken to study on the peeling strength, that was most useful for inspecting the brittleness or toughness of the thin plate joint, in soldering of tin and zinc coated steels. The results obtained are as follows:
(1) Peeling strength of soldered joint did not depend on soldering area and soldering clearance but on soldering width.
(2) Peeling strength of soldered joint on tin cozated steel was dependent on tin content of the applied solder, being minimum at eutectic composition. An opposite relation was found between hardness or tensile strength of solder itself and peeling strength of soldered joint on steel and tin coated steel.
(3) Peeling strength of soldered joint on zinc coated steel showed nearly a constant value of 0.38 kg/mm, independently of tin content of solder.
(4) It was clarified that peeling mechanism of soldered joint on tin coated steel was different from zinc coated steel, the former peeled off the interface between solder and metallic compound FeSn₂ formed in soldering process, and the latter off the metallic compound FeZn₇ formed in zinc coating process.