Liquid Metal Embrittlement of Steel with a Coating Obtained by Batch Hot Dip Method in a Zn + 2% Sn Bath

Abstract

The article presents investigation of steel subjected to external stress during hot-dip metallization. The results of experimental investigations of the LME phenomenon, reasons of its formation and influence of different parameters are described. Samples made of C70D steel subjected to various loads inducing tensile stress (400-800 MPa) during hot dip metallization ina zinc bath with 2% tin addition were investigated. The processes of hot dip metallization were carried out at 450°C temperature and immersion time of 180 s. It can be observed that the stress value can affect the behaviour of metal during the hot dip metallization process. Coated samples were analysed on a light microscope to specify the possibility of the occurrence of LME. These studies provided the basis for the selection of samples and areas for further quantitative andqualitative analysis on a scanning electron microscope (SEM) with a microanalysis system. The analysis of cracks in three microareas revealed that the tin content in the front of a fracture is twice as big as it is in other measuring points. It may be related to crack propagation due to the phenomenon of LME, by the accumulation of the initiating element atoms and those propagating the fracture.