A new method for improving the resistance of high strength steel wires to room temperature creep and low cycle fatigue

Abstract

The effects of warm deformation treatments on the room temperature creep and the low cycle fatigue resistance of high carbon patented steel wires and high strength low carbon low alloy (HSLCLA) steel wires were studied. The low temperature creep strains of high carbon patented steel wires and high strength low carbon low alloy steel were decreased 85 and 65%, respectively, by the warm working treatments for the optimum warm deformation parameters (3% axial tensile plastic deformation at 300°C for 5 min). The low cycle fatigue lives of both steels were increased by 30–35% after warm deformation at the optimum deformation parameters. It is shown that the warm deformation treatment only affected the micro states such as lattice distortion, internal stress, dislocation density, sub-grain size and the amount of solute atoms in solid solution but did not change the overall microstructure or strength of the steel wires. Internal friction studies at different temperatures showed that the amount of solute atoms re-dissolved is different for different warm deformation temperatures and reaches a maximum at 300°C. It is considered that the improvement in the resistance of high strength steel wires to room temperature creep and low cycle fatigue can be attributed to the reduction of the amount of mobile dislocations through the rearrangement of dislocations and strengthening of matrix by the re-dissolution of solute atoms and dislocation pinning.