利用X射线衍射仪和TEM等微观结构分析手段,探讨了韧化处理后300M钢的孔挤压强化机制。研究结果表明,经孔挤压强化后,疲劳强度极限从σ0.1=410MPa提高到σ0.1=530MPa.其强化机制的来源是多方面的,包括在强化层内宏观残余压应力的产生,晶面的拉伸和压缩,晶格的弯曲和歪扭,位错密度的升高,胞状位错的形成,部分残余奥氏体向形变马氏体的转变,孔壁表面粗糙度的降低。当孔边承受交变应力时,由于以上强化机制的综合作用,从而提高了疲劳强度。

The strengthening mechanisms of hole expansion in toughening treated steel 3 00M have been studiedby x-ray diffractometer and TEM. It was shown that the fatigue strength was improved from σ0.1=410MPa to σ0.1=530 MPa after the expansion. The strengthening mechanisms came from many aspects, in-cluding the formation of residual compressive stress, the tension and compression of crystal plane, thebending and distortion of crystal lattice, the increase of dislocation density,the formation of cellular dislo-cations, the transformation of part of the residual austenite to deformation martensite, and the decrease ofthe hole surface roughness,Due to the comprehensive effects of these factors during the fatigue test, thefatigue strengths was thus improved.