Failure analysis at deep drawing of low carbon steels

This paper presents a comparison in behaviour of two Zn coated, low carbon steels during deep drawing of bearing housing. The failures occurred during deep drawing process only for one steel. The experimental work consisted of a visual inspection, microscopic examination and chemical analysis of both materials. Metallurgical tests revealed the difference in microstructure and in carbon content. The anisotropy in behaviour was observed during deep drawing process. Metallography confirmed formation of longitudinal micro and macrocracks and elongated chains of cementite particles in matrix of ferrite. This study highlights the detrimental effect of the interface cementite particle/ferrite matrix as the main reason for the microcracks formation and reduction of steel capacity for deep drawing.