Optimization of strength, ductility and wear resistance of low-carbon grade A shipbuilding steel by post-ECAP annealing

Effect of equal channel angular pressing (ECAP) and subsequent annealing on the microstructure, mechanical properties and tribological behavior of grade A shipbuilding steel was investigated. Coarse-grained microstructure of initial sample is eliminated during the ECAP at 375 °C and more refined microstructure is achieved. Post-ECAP annealing at 575 °C results in some grain growth, and also the cementite lamellae in the pearlite colonies is broken and got spheroidised during the annealing treatment. ECAP increases strength and hardness of steel significantly while it decreases the ductility. On the other hand, post-ECAP annealing treatment brings about an increase in ductility and diminishes the hardness, as expected. Strain hardening capacity, ductility, hardness and oxidation rate were found to be the main factors affecting wear resistance of the grade A steel. It was found that high hardness and strength, good wear resistance with sufficiently high ductility can be achieved in the grade A steel by applying ECAP + annealing processes.