碳化物的位向及尺寸对高铬铸铁耐磨性的影响

本文对成分为3.56%C及16.2%Cr的共晶高铬铸铁采用定向凝固的方法,获得了碳化物呈不同粗细的纤维状定向排列的试样。对它们进行了湿砂橡胶轮磨损、三体磨损、冲蚀磨损及冲击韧性试验,并以砂型铸造的试样作为对比。结果表明:在碳化物数量、碳化物类型及基体组织均保持恒定的条件下,碳化物垂直于磨损面定向排列时,耐磨性最高,尤其是在软磨料低角度冲蚀磨损的情况下,其耐磨性比砂型铸造试样的高156%。至于碳化物的粗细与耐磨性的关系与磨损条件有关,并不都是碳化物愈细耐磨性愈好。当碳化物纤维尺寸相同时,冲击方向与纤维相平行时的冲击韧性与砂型铸造的十分接近。

THE EFFECT OF CARBIDE ORIENTATION AND THICKNESS ON THE ABRASIVE WEAR RESISTANCE OF HIGH-Cr CAST IRON

By using unidirectionaI solidification technique, the test blocks of high-Crcast iron containing 16. 2% of Cr and 3. 5% of C were preoared to provide unidi-rectionally arranged carbide fibres. The carbide thickness in the blocks was dif-ferent at different levels. For comparison, some blocks were east in sand. In allspecimens cut from the test blocks, the carbide content, the carbide form andthe microstructure of matrix were the same. The wear resistance of the specimens was measured in rubber wheel testwith wet sand. Three body abrasion test and erosion test, and the impact strengthtests were carried out. It was found that wear resistances of the specimens withcarbide fibres perpendicular to wearing surface were higher than those of others.This was so especial in erosion teats with low attack angle using soft abrasives.The effects of carbide thickness on wear resistance were quite different in dif-ferent tests. Therefore, fine carbides cannot be considered as always beneficialto wear resistance. The impact strength of the specimens with carbide fibresparallel to impact direction was found to be close to that of sand cast ones.