硅对贝氏体铸钢高应力冲击磨损性能的影响

Effect of Si on Wear Resistance of Bainitic Cast Steel under High Stress Impact

研究了不同硅含量 (0 .7%～ 2 .4% ,质量分数 ,下同 )贝氏体铸钢的抗高应力磨损性能和失效机制。结果表明 :高硅贝氏体铸钢的耐磨性能较低硅钢显著提高 ,其磨损失重约是低硅贝氏体铸钢的 1/ 2。这是因为硅使贝氏体铸钢在高应力冲击磨损下表现出不同的失效机制。低硅 (0 .7% )贝氏体铸钢由于韧性低、组织结构粗大及树枝晶的微区成分偏析 ,故材料抵抗冲击的能力很低 ,常在表面还未形成强烈变形层 (白层 )甚至变形层时 ,就在变形层和材料基体内产生裂纹并扩展 ,故低硅贝氏体铸钢的失效方式为变形层和基体剥落机制。而硅含量为 1.6 %～ 2 .4%的高硅贝氏体铸钢 ,因脆性的渗碳体被韧性的残余奥氏体所代替 ,钢的韧性显著提高 ,失效方式表现为白层的剥落机制。

The high stress wear resistance and mechanism for bainitic cast steels with different Si content (0.7 %～2.4 %) have been studied systematically. The experiments have shown that the wear loss of high Si bainitic cast steels is only about 1/2 times as that of low Si bainitic cast steels, showing better wear resistance of the former under high stress impact. The reason is that the impact wear mechanism is different for low and high Si bainitic cast steels. Low Si bainitic cast steel has poor wear resistance under high stress impact because of its low toughness, coarse dendrite and micro segregation, etc. So the damage cracks are easily formed in the wear surface before formation of white layer, and propagate inside the deformation zone and matrix, exhibiting mechanism of deformation zone and matrix delamination. The impact toughness of high Si bainitic cast steels are improved apparently for the reason that the brittle cementite is replaced by ductile retained austentite film, resulting in the brittle delamination of white layer.