Mechanism of surface rust defects on tinplate strip steel during storage and transportation

Abstract

This study elucidates the rusting mechanism on tinplate during storage and transportation. It was found that the absence of a Sn layer on the sheared edges, combined with a thinner Sn layer in the centre compared to the edges, leads to increased ATC values and porosity at the centre. Consequently, this results in diminished rust resistance at both the sheared edges and central regions. Simulations of storage and transportation conditions, along with electroplating experiments, demonstrated that waviness in the tinplated substrate contributes to higher porosity and reduced thickness of the Sn–Fe alloy layers in both electroplating and reflowing processes. Moreover, the choice of electroplating processes significantly influences the rust resistance of tin-plated plates. The adherence of rust factors during the tinplating process, particularly when subjected to condensation during storage and transportation, exacerbates the rust of tinplate.