Cementite nano-crystallization in cold drawn pearlitic wires instigated by low temperature annealing

Abstract

The effects of low temperature annealing on the cementite structure and mechanical properties of cold drawn pearlitic steel wires were investigated. It was found that the thermal annealing at a temperature as low as 483 K could transform cementite in the as-drawn steel wires (ϵ = 2.0) from amorphous to nano-crystalline state. Against the conventional belief, the low temperature annealing treatment could simultaneously enhance the tensile strength and ductility of the cold drawn wires, for example, by 10% through the annealing treatment at 483 K. The underlying mechanisms responsible for enhanced mechanical properties were discussed, with a focus on the effects of solute carbon diffusion and cementite nanostructure.