Microstructure and performance of 2Y-PSZ/TRIP steel composites

2Y-PSZ/TRIP steel composites have been sintered by the hot-pressing method. Their microstructure and mechanical properties were investigated by means of SEM, TEM, XRD and static tension, split Hopkinson pressure bar method. The results showed that the strength and the elastic modulus of 2Y-PSZ/TRIP steel composites at room temperature decreased with the increase of 2Y-PSZ content. The main reason was that the combining strength was quite weak between the grains of ZrO₂. The distortion induced martensite transformation and plasticity during the dynamic loading increased the strength and the distortion capability of the 2Y-PSZ/TRIP steel composites. The transformation was carried out mainly through the twins formation. The shape of the martensite induced by distortion was lamellated with substructures of twins. The habit plane was near (259)_γ with no mid-ridge phenomenon and no explosion phenomenon. The interface was straight between the austenite and the martensite induced by distortion. The increase of 2Y-PSZ content, on the one hand, made the composite dynamic flow stress improved. Thereby, the fracture strength was improved. On the other hand, it depressed both the distortion capability and the martensite transformation induced by distortion. This resulted in the decrease of the dynamic fracture strength.