Dimensional change in high carbon steel wire owing to heavy reduction by tandem cold drawing

Abstract

Curious behaviour has been found in a heavily reduced high carbon steel AISI 1070. A wire of 1˙5 mm in diameter manufactured through tandem cold die drawing with total elongation of 13˙4 was subjected to heating. When it was heated above 473 K, remarkably, the length of specimen slightly increased after cooling. The ratio of increase in length was about 0˙1%. The decrease in diameter was slightly larger than the expected value to ensure the volume constancy condition owing to plastic metal working. This change in dimensions did not occur in the parent wire of 5˙5 mm in diameter, and it was concluded that this change was induced by heavy reduction by cold tandem drawing. SEM observation showed the occurrence of new isolated cementite when the heating temperature exceeded 473 K and it was assumed that it might be closely related to the mechanism through which increase in length occurs.