The welded joint of rails will form a heat-affected zone after thermal cycling. In the heat affected zone,due to the existence of incomplete phase transformation affected zone,the hardness decreases and the softening occurs. Severely softened joints will produce saddle-shaped wear after service,resulting in uneven lines. In this paper,the variation of hardness in softening zone of high-strength wear-resistant steel rail gas pressure welding joints under different cooling conditions are studied. The results show that in the cooling process,the cooling rate is increased by jet-air and spraying,which has a significant effect on reducing the width of softening zone of the joint. The hardness of the softest point of the welded joint increases with the strength of the base metal,but the higher the strength of the rail,the lower the ratio of the softest point to the hardness of the base metal. When the rail is at the strength level of 1 280 MPa and above,the hardness standard requirement of the softening zone of the pressure welding joint(H,J1,/H,P,≥0.8) is difficult to be stably met. It is recommended to modify or reduce the index requirement.
railgas pressure weldingsoftening zonehardnesscooling process