Cr元素对热轧耐磨钢显微组织和耐磨性的影响

Effect of chromium on microstructure and wear resistance of hot-rolled wear-resistant steel

对两种热轧耐磨钢(Cr质量分数分别为0和0.65%)经过在线层流冷却后的组织性能进行了研究,使用磨损试验机MLG-130在60 N载荷下进行摩擦磨损试验,利用场发射扫描电镜分别对试样磨损表面进行观察。两种耐磨钢冷却后组织为铁素体和马奥岛,由于Cr元素的加入,含Cr钢组织中以马奥岛为主,体积分数为82.6%。此外,在不同磨损时间下含Cr钢的耐磨性均优于无Cr钢。经过0.5、1和1.5 h磨损后,含Cr钢的磨损失重分别为0.357 8、0.769 5和1.427 2 g,其耐磨性分别为1.40、1.30和1.05 g^(-1)。无Cr钢磨损表面出现了明显的犁沟和剥落坑,磨损机制主要为微犁削和微断裂。而含Cr钢由于屈服强度和表面硬度更高,塑性变形被抑制,因此磨损表面更加光滑平整,主要磨损机制为微切削和微断裂。

Microstructures and mechanical properties of two hot-rolled wear-resistant steels with 0 and 0.65% Cr were investigated after online laminar cooling. Wear tests of samples were carried out by MLG-130 abrasion-test equipment under the load of 60 N. Then worn surfaces of samples were studied by field emission scanning electron microscopy(SEM). These results showed that the microstructure of both wear-resistant steels consisted of ferrite and martensite/austenite constituents. Due to Cr addition, the microstructure of Cr-alloyed steel was dominated by martensite/austenite constituents, the volume fraction of which was 82.6%. Moreover, the wear resistance of the Cr-alloyed steel was better than that of the Cr-free steel after wear testing with different times. After wear testing for 0.5, 1 and 1.5 h, the abrasion weight of the Cr-alloyed steel was 0.357 8,0.769 5 and 1.427 2 g and the wear resistance is 0.48, 0.30 and 0.22 g^(-1), respectively. The worn surface of the Cr-free steel was characterized by furrows and peeling pits, and the main wear mechanism was micro-furrow and micro-fracture. For the Cr-alloyed steel, plastic deformation was suppressed due to its higher yield strength and hardness, which caused the worn surface became smoother and flatter, and the main wear mechanism was micro-cutting and micro-fracture.