Thermal Fatigue Behavior of New Type High-Cr Cast Hot Work Die Steel

The thermal fatigue (TF) behavior of a new type high-Cr cast hot work die steel was investigated. The results indicate that TF cracks initiate at the grain boundaries or at the interface between inclusion and matrix, which had been oxidized, and then propagated along the grain boundaries. The thermal fatigue crack initiation and propagation have been accelerated greatly by oxidation. The new type cast high Cr hot work die steel has a better thermal fatigue resistance compared to 4Cr5MoSiV1(8407) steel under thermal cycling temperatures of 650-25°C. Good oxidation and temper resistances are the main causes for the better TF resistance of the new type high-Cr cast hot work die steel.