Effects of Process Conditions, Material Properties, and Initial Shape of Flaw on the Deformation Behavior of Surface Flaw during Wire Drawing

摘要

The effects of process conditions, material properties, and initial shape of flaw on the deformation behavior of surface flaw during wire drawing process have been investigated to understand the deformation behavior of surface flaw and to find solutions to decrease them using the finite element (FE) analysis. The surface flaw decreased with decreasing die angle and friction coefficient, and with increasing reduction of area (RA) per pass. Interestingly, the surface flaw and strain inhomogeneity of wire rod were simultaneously decreased at the same process conditions. The shape of surface flaw was somewhat varied with strain hardening exponent (n) and almost same regardless of strain hardening coefficient (K), which means the effect of material properties such as K and n values is not critical. The higher flaw angle has a positive effect on removing or reducing the surface flaws during wire drawing process. The V shape surface flaw in wire rod was relatively well removed; whereas, U shape flaw tends to deform in the manner of overlap with increasing total RA, which means U shape surface flaw was much more detrimental than V shape flaw. To reduce or remove the surface flaw during wire drawing, homogeneous plastic deformation along the radial direction was necessary. Based on above results, seven strategies were proposed to remove or reduce the surface flaw of wire rod during wire drawing process, which can be helpful in determining the guideline to design the wire drawing process.