新型精铸热锻模具钢高温磨损性能同其显微组织的相关性

Correlation between Microstructures and High-Temperature Wear-Resistance of a New Type Hot-Forged Precisely Cast Die Steel

研究了经不同热处理条件下的新型精铸热锻模具钢的组织同其高温磨损性能的相关性,对比分析了新型铸钢与H13锻钢的高温磨损性能,并探讨了其磨损机理.结果表明:新型精铸热锻模具钢的高温耐磨性能明显优于锻钢H13;在马氏体、贝氏体和马贝复相3种组织中,贝氏体和马贝复相的高温耐磨性能较好,马氏体相的高温耐磨性能最差;经过400～620℃回火处理的新型精铸热锻模具钢的硬度为42～43HRC,高温耐磨性能较好;当回火温度大于650℃或小于400℃时,新型精铸热锻模具钢的磨损率明显增大,耐磨性显著降低.

The correlation between the microstructures and wear-resistance of a new type hot-forged cast die steel was investigated using forged steel H13 as a comparison. Thus the microstructures of the hot-forged precisely cast die steel after being heat-treated at different conditions were examined by means of transmission electron microscopy. The hardness of the new-type cast die steel specimens was measured, and their wear behavior under dry sliding against W18Cr4V2 steel at elevated temperature was evaluated using a pin-on-ring test rig. Moreover, the morphologies of the worn surfaces of the new-type cast die steel specimens and the H12 forged steel specimen were observed using a scanning electron microscope. It was found that the new-type cast die steel specimens had better wear-resistance at elevated temperature than the H13 forged steel specimen. And the wear-resistance of the new-type cast die steel specimens was greatly dependent on the microstructures. Namely, the new-type cast die steel specimens tempered at 400-620°C had better wear-resistance at elevated temperature, while those specimens tempered above 650°C or below 400°C had poor wear resistance at elevated temperatures. The better wear-resistance of the new-type cast die steel specimens tempered at 400-620°C was attributed to the formation of bainite and martensite plus bainite microstructures, while the formation of martensite microstructure led to a significant decrease in the wear-resistance of the new-type cast die steel specimens tempered at a too high or too low temperature. Moreover, both the new-type cast die steel specimens and the H13 forged steel specimen were characterized by adhesion wear and oxidation wear in sliding against the W18Cr4V2 steel at elevated temperatures.