低合金高强钢延迟裂纹断口分析

The Fractography of Delayed Crack in HSLA Steel

本文用宏观分析与微观分析相结合的方法，对几种典型低合金高强钢的插销试棒断口形貌进行了分析。结果表明：钢材的Ｐｃｍ值及插销试验时的承载应力均影响断口形貌。在裂纹启裂及缓慢发展区中，断口组成是ＩＧ＋ＱＣ，随着Ｐｃｍ及承载应力变化，其所占比例也在改变。在裂纹快速扩展区的断口形貌主要为ＱＣ，但不同Ｐｃｍ其ＱＣ内部微细结构发生了变化。在终断区以ＤＲ为主。但随着承载应力的增加，Ｐｃｍ的降低，ＤＲ区所占面积增加且ＤＲ直径变大，深度加深。

Analyses the fracture surfaces of the specimens of HSLA steel by the method of combining the macrographic analysis with the micrographic analysis in the implant test.The results indicate that the fracture surface is mainly affected by P cm of steel and the bearing stress.The fracture in the initial and slow extensive area is consisted of IG+QC.The change of the proportion in the fracture depends on P cm and the bearing stress.When the fracture propagates fast,the fracture surface is mainly QC,but the variation of P cm affects the microstructrue of QC.The final fracture area is mainly DR.When the bearing stress is increased or P cm is decreased,the area of DR is extended,and the DR diameter becomes big and its depth deepens.