材料期刊网

文中详细分析了目前孔型设计对于钢轨质量的影响的各种因素和存在的问题,并对于帽形孔中切入楔子的深度和角度进行了比较细致的研究。此外在钢轨轧制过程中每一道次机械性能的变化作了全面的比较分析并探讨了产生这些变化的原因。 结果指出了: 1.在帽形孔中切入楔子的深度和角度的变化,对轨底的机械性能影响不大,因此可以采用比较矮而钝的楔子。此外不均匀变形对成品性能的影响亦不大,因此采用2个或4个帽形孔主要决定于设备条件和生产情况。 2.随着轧制道次的增加,轧件性能有很大的变化。在第二孔或第三孔轧制后,轧件的机械性能有下降的现象,但第六孔以后,轧件的性能则变化很小。较快冷却情况下,加工温度对成品的机械性能影响不大,因此可以考虑提高加工温度、加工量和轧制速度,从而把孔型数目减少。

The effects of roll pass design on the mechanical properties of rails and the changes inmechanical properties in the processes of rolling and the causes for these changes have beeninvestigated. The height and the angle of the wedge in the trapezoidal passes have also been stu-died. The results show that in the trapezoidal passes a change in the height and the angle of thecutting-in wedge has little effect on the mechanical properties at the foot of the rails; hence itis better to use wedges with a smaller height and a greater angle. It is found that the effect ofinhomogeneous deformation on mechanical properties is also small; hence the question of using2 or 4 trapezoidal passes may be settled by consideration of the mill construction and the condi-tions of production only. The mechanical properties of the bloom undergo considerable changes when it is rolledthrough the successive passes. After the second or the third pass, a lowering in mechanical pro-perties has been recorded; but after the sixth pass the changes in mechanical properties becomesmall. When the rate of cooling is great, the temperature of rolling has little effect on themechanical properties; hence, it is possible under this condition to increase the temperature ofrolling, the amount of reduction and the speed of rolling in order to achieve a reduction in thenumber of passes used.