含碳量对过共晶高铬铸铁显微组织与耐磨性的影响

Effects of Carbon Contents on Microstructure and Wear Resistance of the Hypereutectic High Chromium Cast Iron

通过显微组织观察、图像分析仪定量金相测定,力学性能测试,低应力湿态磨料磨损试验,研究了碳对含33.5%Cr的过共晶高铬铸铁的影响。结果表明,过共晶高铬铸铁显微组织主要特征是含有较大尺寸的六边形和杆状M7C3型初生碳化物。并且随着含C量的升高,过共晶高铬铸铁组织中的初生碳化物逐渐变得粗大,初生碳化物和碳化物总体积分数增加。随着含碳量的增加,过共晶高铬铸铁硬度逐渐升高。含4.80%C的高铬铸铁硬度最高,达到HRC65.5。但随着含碳量的增加,高铬铸铁的冲击韧度逐渐下降。在40 N、70 N、100 N载荷下,随着含C量的增加,过共晶高铬铸铁的耐磨损性能提高。在40 N、70 N和100 N载荷下,含4.80%C的高铬铸铁的耐磨性分别比含3.86%C的高铬铸铁提高了26.1%、24.5%和24.1%。在含碳量相同的情况下,重载荷下高铬铸铁的耐磨性能下降。随着载荷的增加,高含碳量高铬铸铁的耐磨性优势逐渐下降。与含23%Cr的过共晶高铬铸铁相比,含C量分别为3.86%、4.13%、4.65%和4.80%的含33.5%Cr的过共晶高铬铸铁耐磨性分别提高了42.9%、52.0%、54.6%、56.6%。

The effects of carbon contents on microstructure and wear resistance of the 33.5% Cr hypereutectic high chromium cast iron were investigated by optical microscope, quantitative metallographic determination on image analyzer, mechanical properties tester, low-stress wet-abrasive wear. Experimental results show that the mainly microstructure characteristic was hexagon and rod-shaped coarse primary M7C3 carbides. With the increase of carbon content, the primary carbides grew larger, the volume of primary carbides and total volume of carbides became larger, but the impact toughness declined and the wear resistance increased gradually. Under 40 N, 70 N, 100 N loads, the wear resistance of specimens with 4.80% C were improved 26.1%, 24.5%, and 24.1% than that of specimens with 3.86% C. With the increase of load, the wear resistance of high chromium cast irons with the same carbon contents decreased, and the advantage of wear resistance decreased too. Compared with 23% Cr hypereutectic high chromium cast iron, the wear resistance of the 33.5% Cr hypereutectic high chromium cast irons with 3.86% C, 4.13% C, 4.65% C, 4.80% C were improved 42.9%, 52.0%, 54.6% and 56.6%, respectively.