高钒耐磨合金在不同冷却方式下的高温氧化行为

研究了950℃高温下高钒耐磨合金的高温氧化行为,并研究了在随炉冷却和空冷两种不同冷却方式下的氧化增重与开裂行为.结果表明:氧化初期材料表面发生"暂态氧化",所有元素均参与氧化反应,随后在炉冷时氧化增重比空冷时的氧化增重要大的多,当氧化8 h后单位面积氧化增重分别为82.7 mg·cm-2与39.1 mg·cm-2,炉冷与空冷氧化增质量相差一倍多.虽然在基体/氧化层界面形成了能起到一定保护作用的50～200 nm厚Cr2 O3致密氧化层,但同时也存在疏松氧化层;而炉冷时样品以生长应力为主,氧化层发生"翘曲"现象,但较少引起氧化层脱落.然而空冷时冷却速度较大,氧化层内易产生较大热应力,致使氧化层较易开裂或者脱落.

High temperature oxidation behavior of high-vanadium wear resistant alloy in different cooling approaches

The oxidation mass increasing method was adopted to explore the oxidation behavior of high-vanadium wear-resistant al-loy at 950℃. The oxidation mechanism and cracks behavior were studied with different cooling types ( furnace cooling and air cool-ing) . The results indicated that the weight increment per unit area was obviously large at the beginning of the oxidation due to the ma-trix being in direct contact with the air. Additionally, the oxidation increase gains of furnace and air cooling were 82. 7 mg·cm-2 and 39. 1 mg·cm-2 , respectively, after 8 h of oxidation. At the same time, the preferential formation of Cr2 O3 was observed with 50-200 nm at the matrix and oxidation layer interface. Remarkable thermal stress was produced in the oxidation layer due to the larger cooling rate. The warped phenomenon appeared at the oxidation layer due to the production of growth stress. However, the shedding phenomenon rarely occurred in the oxide layer.