The effect of cyclic heat treatment on the structure of 5140 steel after cold plastic deformation

The objective of this work are experimental research of steel 5140 damages appearance under cold plastic deformation and healing continuity defects characteristic study by following periodic heat treatment. The experimental research of deformation defects continuity appearance in steel 5140 with the granular and lamellar perlit under cold plastic deformation in dependence to original structure was conducted. The deformation defects appearance pattern in steel, their growth in dependence to degree of deformation, microstructure and capacity for healing in the process of cold forging are seemed to be pertinent are explored. It was concluded, that at early deformation stages independently of perlit morphology in steel 5140 the damage is related to micropore appearance in ferrite. The possibility of defects healing by periodic heat treatment is found out. For damage changes studying in the process of cold plastic deformation and healing heat treatment the following experimental design was used: the preliminary periodic heat treatment - deformation with varying degrees - healing periodic heat treatment - deformation up to failure. The periodic heat treatment with phase recrystallization is shown to bring about more full healing damages in comparison with recrystallization annealing. Herewith the microdefects critical size increases up to 2 micrometers, and invertible damage stage extend to 0.4. © Published under licence by IOP Publishing Ltd.