含碳量对20%Cr合金氧化和高温磨损性能的影响

对不同含碳量的20%Cr合金进行了900℃大气气氛下的抗氧化性试验，测定了在此温度下的氧化动力学曲线，并在自制的高温磨损试验机上进行了800℃的高温磨粒磨损试验。用扫描电镜及电子探针分析和测定了氧化、磨损面的形貌及其亚表层的组织及成分分布。试验表明，随含碳量增加，氧化过程由良性的外部氧化转向恶性的内部氧化，从而使合金的抗氧化性下降。合金中共晶碳化物（Cr，Fe）7C3在高温下有较高的硬度和稳定性，因此，合金含碳量的增加，提高了800℃时的抗磨性。在高温磨损过程中由于基体组织的变形而使碳化物折断。因此，基体抵抗变形的能力将对利用碳化物来提高合金的抗高温磨损性能起到重要的作用。

INFLUENCE OF CARBON CONTENT ON THE OXIDATION AND WEAR RESISTANCE OF 20% Cr ALLOY AT ELEVATED TEMPERATURE

Oxidation test in atmosphere of 20%Cr alloy with different carbon content was carried out at 900℃ and their kinetic oxidation curves were determined at the same temperature. Abrasive wear test was conducted at 800℃ in a self-made high temperature wear tester. The morphologys of oxidized worn surface and the subsurface were observed by SEM. The composition distribution of the subsurface was determined by microprobe. The main conclusions were: (1) With increasing carbon content a change from normal external oxidation to catastrophic internal oxidation took place, resulting in a decrease of oxidation resistance (2) The eutectic carbide in alloy was hard and stable in high temperature, so that the increase in carbon content could increase the wear resistancs at 800℃. (3)Carbide fractured due to plastic deformation of the matrix in the wear at elevated temperature. Hence, the resistance to increase the wear resistance of the alloy.