Effect of Die Angle and Frictional Conditions on Fine Grain Layer Generation in Multipass Drawing of High Carbon Steel Wire

Fine grain layers that generate near frictional interfaces in metal forming processes affect the quality of products. The present paper aims to contribute to the continuum-mechanics-based phenomenological approach for predicting such layers' properties. In particular, it studies the generation of fine grain layers in the process of multipass drawing of thin high carbon steel wires experimentally. The wires are drawn in three passes under different friction conditions. All three dies in each multipass process have the same semiangle. In total, two die semiangles are used, 4 degrees and 5 degrees. The effects of such processing conditions as the die semiangle, the number of passes, and the friction conditions on the thickness of fine grain layers are observed and discussed. The criterion for determining this thickness is based on the coefficient of anisotropy. Under soft friction conditions, the fine grain layer's thickness decrease occurs during the consequential passes independently of the die semiangle. On the other hand, in the case of hard friction conditions, the thickness may or may not be a monotonic function of the number of passes, and its general qualitative behavior depends on the die semiangle.