Influence of the mode of thermal treatment and load ratio on the cyclic crack-growth resistance of wheel steels

We study the microstructure, mechanical properties, and micromechanism of fatigue fracture of high-strength railway-wheel steel (0.63% C and 0.1% V). The necessity of elevation of the cyclic fracture toughness of this type of steel by isothermal hardening and tempering at 500°C is substantiated. It is shown that the cyclic crack-growth resistance of steel decreases for high loading amplitudes as the load ratio (simulating the influence of residual thermomechanical stresses) increases.