珠光体球化对20G拉伸力学性能的影响

Effect of Pearlite Spheroidization on the Extensibility of 20G

珠光体球化是低碳钢材质20G材质老化的主要表现形式。它使20G材质的拉伸力学性能发生变化,随着球化程度的加深,抗拉强度和屈服强度都会降低,屈服强度降低得更加明显,其降低幅度以完全球化阶段为最大,但其塑性指标稍有改善。本文分析了珠光体球化导致这些变化的微观机理,指出材质老化过程中珠光体的球化会减小位错运动的阻力,使得材料的屈服强度降低,塑性略有上升。并综合材质的拉伸力学性能的变化与实际焦炭塔在工作循环中温度、应力的变化详细地分析了焦炭塔产生腰鼓变形的原因。

Pearlite spheroidization is the main change during the degradation of mild steel of 20G which results in changes for the extensibility of 20G that involves with the development of material degradation, the tensile strength and yield strength both decrease, among which the yield strength reduces more obviously whose amplitude of decline comes to the most when the materials is in the stage of complete spheroidization while plasticity rises a little. In the essay the micro mechanism of the pearlite spheroidization's causing these changes is analyzed, and it showed that in the development of degradation the spheroidization of pearlite can make less obstructs to the movement of the dislocation, which decreases the yield strength and enhances the plasticity of the material a little. At the same time the reason why coking tower have the deformation in the waist of the tower was dwelt on considering both the changes of the extensibility of the material and the changes of the temperature and stress experienced by the coking tower in the cycle of its operation.