Free surface roughening under simple tension

Abstract

The effect of process parameters on surface roughening under simple tension in a tensile test is investigated. The assumption that the surface roughness is caused by the difference between the axial tensions of the top and bottom of the asperities in the thickness direction on the surface layer is used to model the free surface roughening. An equation is derived for the relationship between surface roughness and process parameters such as the initial roughness, effective strain, strain hardening exponent, and normal anisotropic value. In a tensile test, free surface roughness decreases nonlinearly as the normal anisotropic value and strain hardening exponent increase; it increases linearly with effective strain or grain size. Experimental results support the proposed model, which improves our understanding of the mechanism of the free surface roughening of sheet metals under tension.