Coverage and Microstructure of Fe-Sn Alloy Layer on Tinplate Formed at High Temperature Region

Abstract

The morphology of Fe-Sn alloy layer on tinplate formed at temperature between 237 and 700°C was investigated. The alloy formation was carried out by the use of an infrared heating furnace which was capable of varing alloying temperature and its heating rate.
The alloy layer formed between 400 and 550°C had granular structure and improved degree of coverage on steel surface which was remarkably different from usual alloy layer formed at normal reflowing condition (pillar structure). The morphology of alloys did not change even if the heating rate varied. It was found that the crystal structure of alloys on fully-alloyed tinplates produced during heat-treatment whose alloying temperature varied from 400 to 700°C changed in the order FeSn₂→FeSn→Fe₃Sn₂→Fe₃SnC with increasing alloying temperature. The degree of coverage of the alloy layer improved as alloying temperature was elevated.