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采用膨胀法,辅以金相法测定了Mn-Cr-Mo系空冷贝氏体钢轨钢的连续冷却转变曲线,结合不同冷速下的金相组织观察,分析并讨论了成分的选择及合金元素的作用。结果表明:由于合金元素的添加提高了贝氏体淬透性,试验钢在空冷速度0.05~2℃/s内即可得到贝氏体,为避免出现马氏体,应将冷速控制在4℃/s以下,最佳冷速应控制在0.8~2℃/s内,可得到性能优良的下贝氏体。
The continuous cooling transformation curves of the Mn-Cr-Mo air-cooled bainitic rail steel were determined by the dilatancy method combined with the metallographic method. The metallurgical microstructures of the Mn-Cr-Mo air-cooled bainitic rail steel were analyzed and discussed with the compositional choices and alloying elements . The results show that the addition of alloying elements increases the hardenability of bainite. The bainite can be obtained from the test steel at air cooling rate of 0.05 ~ 2 ℃ / s. To avoid martensite, the cooling rate should be controlled at 4 ℃ / s or less, the best cooling rate should be controlled at 0.8 ~ 2 ℃ / s, the lower bainite can be excellent performance.