Study on Die Steel for Die Casting Die (3rd Report)

Thermal Fatigue Characteristics for Tufftriding and Sulphonitriding Treated on Die Steel Sample

Abstract

The effects of tufftriding and sulphonitriding treatments on the life of hot die steel have been investigated. The thermal fatigue test, erosion test, X-ray probe microanalyses and optical microscopy of hot die steel samples were carried out after tufftriding and sulphonitriding treatments. It was found in the thermal fatigue test that the number of cracks per unit area of tufftrided and sulphonitrided samples markedly smaller than those of ordinary SKD61 sample. For the tufftrided sample, the high concentration region of nitrogen, i.e., Fe_2-3N compound layer, disappeared and became a diffusion layer after the test. For the sulphonitrided sample, the surface layer was contained oxide and nitride, and the nitride was disappeared after the thermal fatigue test. In the erosion test, the sulphonitrided sample showed the most excellent erosion resistance, i.e., 10 times of the tufftrided sample and 30 times of the ordinary SKD61 sample.