20MnMo钢内裂纹修复现象的发现及其金属组织的变化

通过物理模拟研究，发现了２０ＭｎＭｏ钢内裂纹在高温下可修复的现象，并总结了其初步规律，认为这种修复过程主要是由原子的扩散迁移所造成．内裂纹的修复可分为空洞填充和晶粒长大两个阶段。填充物初期由细小晶粒所组成，存在Ｆｅ的成分偏析，与基体的分界面清晰．随后的晶粒长大与成分均匀化同时进行．一定的塑性变形，可使内裂纹及空洞等被很好的填充和压合．为保证内裂纹的完全修复，需一定的保温时间，使晶粒充分长大．

DISCOVERY OF INNER CRACK RECOVERY AND ITS STRUCTURE CHANGE IN 20MnMo STEEL

By physical modelling, the recovery phenomenon of inner crack in 20MnMo steel at high temperature was discovered, and its regular pattern was concluded.It was believed that the recovery process was mainly controlled by the diffusion and migration of metal atoms. The recovery process can be divided into two steps, void filling and grain growing. The filling materials consisted of many very fine grains with segregation of iron. There was a very clear boundary between the filling materials and matrix. The grain growing and composition homogenzing occurred simultaneously. Inner cracks and voids can be filled and taken away in a certain deformation. A certain holding time was necessary for grain growing and inner crack recovery entirely.