【摘要】 采用电子光学等分析手段和机械性能试验方法,测定了不同热处理状态下65Cr4W3Mo2VNb（简称65Nb）钢的各种显微组织参量和机械性能。根据试验结果,从合金化、热处理和冶金质量的角度,探讨了影响强度、韧性和疲劳性能的组织因素。得出如下主要结果:（1）Nb的作用在于既能生成稳定的NbC,又可溶入其它碳化物中,从而影响相变过程和相变组织,提高钢的强韧性和工艺性能。（2）韧性第二相和基体的塑性对K_（?）、α_k值起有利影响,而强度主要受碳比物弥散强化所控制,细化晶粒则对两者均有益。工艺——性能曲线上的峰值或谷值,是由于在相变过程中不同强韧化机制。（3）冶炼方法对拉伸性能无甚影响。但电渣钢的韧性和抗疲劳性能比电弧钢高。（4）△K_th对微观组织比较敏感.而中速区的（da）/（dN）则主要取决于基体的韧性。更多还原

【Abstract】 The various microstructures and mechanical properties of the 65Cr4W 3 Mo 2 VNb（Sim-plified as 65Nb）steel in different heat treating conditions were determined by means of electronmicroscopic analysis and the mechanical property tests.According to the experimental result,thestructure factors in view of alloying,heat treatment and metallurgical quality,that influenced thestrength,toughness and fatigue were discussed.The principal result may be discribed as follows:（1）the action of Nb is not only to form stable NbC but also to dissolve in other carbides,（2）the tough second phase and the ductility of the matrix have a beneficial effect on K_?,ak,but the strength is controlled mainly by carbides dispersion strengthening,and so the grainrefining is beneficial to both.The peak and the valley on the property curves are due to the differ-ent mechanisms of strengthening and toughening during Phase transformation.（3）Smelting methodhas no effect on elongation properties,but the toughness and fatigue of steel made in electroslagfurnace are better than that made in are furnace.（4）△K_th is sensitive to the microstructure,and da/dN in mid-speed area mainiy depends on the toughness of matrix.更多还原