25Cr2Ni2MoV钢的固有疲劳门槛值  

THE INTRINSIC FATIGUE THRESHOLD OF 25CR2NI2MOV STEEL

作　　者：沈学成 杜彦楠 朱明亮[1] 黄毓晖[1] 轩福贞[1] SHEN XueCheng;DU YanNan;ZHU MingLiang;HUANG YuHui;XUAN FuZhen(School of Mechanical and Power Engineering,East China University of Science and Technology,Shanghai 200237,China;Shanghai Special Equipment Inspection Technology Research Institute,Shanghai 200062,China)

机构地区：[1]华东理工大学机械与动力工程学院,上海200237 [2]上海特种设备监督检验技术研究院,上海200062

出　　处：《机械强度》2020年第6期1332-1336,共5页Journal of Mechanical Strength

基　　金：国家自然科学基金项目(51922041,51575182)资助。

摘　　要：开展了两种不同热处理(550℃×20 h,580℃×20 h)的25Cr2Ni2MoV钢在应力比R为0.1、0.3、0.5和0.7时的疲劳裂纹扩展实验,分析了疲劳门槛值ΔKth的变化规律及其微观机理。研究结果表明,ΔKth随R增大而减小,在较低R下热处理对ΔKth有不同程度的影响,在较高R下热处理影响不大。断口观察表明,低R下试样存在大量面型断裂形貌,随R增大面型断裂形貌逐渐减少,面型断裂百分比随ΔK变化呈现抛物线分布规律。R与微观组织是影响ΔKth的重要因素,在较高R下裂纹闭合减弱,ΔKth代表着材料的抗疲劳能力,可以认为是材料的固有属性,并建立了估算公式。Fatigue crack growth tests of 25 Cr2 Ni2 MoV steel with two different heat treatments(550℃× 20 h,580℃× 20 h) were conducted at stress ratios R of 0.1,0.3,0.5 and 0.7,and the fatigue threshold,△Kth,and microscopic mechanism were investigated.Results showed that △Kth increased with the decrease of R,and the heat treatment had varied effects on △Kthunder lower R,while it had less effect under higher R.Fracture morphology observation showed that there existed a large number of facet morphology under lower R,while the facet morphology was gradually reduced with the increase of R.Additionally,the percentage of facet morphology followed a parabolic pattern with △K.It is indicated that R and heat treatment are important influencing factors on △Kth.The crack growth at higher R has weak effect of crack closure,representing the fatigue resistance of the material,and thus can be regarded as the intrinsic property of the material which can be estimated by the proposed model.

关 键 词：25Cr2Ni2MoV钢 疲劳门槛值 应力比 裂纹闭合 物理本质 

分 类 号：TG115.57[金属学及工艺—物理冶金]