【摘要】 对铁路重轨钢的热处理过程进行了计算机数值分析。对离线热处理过程的数值模拟表明,距圆角表面10～18mm处存在一个冷却速度达到7～8℃/s的区域,它处在贝氏体转变的临界冷却速度附近,很容易产生非平衡的异常组织。对在线热处理过程的数值模拟则表明,圆角效应使圆角内部相变区的冷却速度比表面快,从而导致圆角内部的硬度高于表面,这与实验结果是一致的。尽管钢轨心部总的冷却速度比表面慢,但相变区的冷却速度却有可能较快,若控制不好,甚至会在钢轨心部形成非平衡组织区域,对材料性能不利。更多还原

【Abstract】 A numerical method has been used to analogize the heat treatment of heavy rail steel. A simulation example for offline heat treatment showed that there is a zone of cooling speed 78 ℃/s at 1018 mm from the surface of circular bead. The zone is just in the vicinity of critical cooling speed of bainite transformation and is easy to cause abnormal disequilibrium structure. The calculated result for online heat treatment showed that the circular bead effect in heat treatment makes the cooling speed in transformed zone inside circular bead more than that on the surface. This would make the hardness inside circular bead more than that on the surface. The calculated results are in accord with experimental results. Although the total cooling speed of the rail core is slower than that of surface, the cooling speed of transformation zone could be greater. If the control is not proper, there will be disequilibrium structure in the rail core, deteriorating the rail performance.更多还原