船用10CrNiCu钢缺口拉伸性能及临界损伤参数研究

Research on Tensile Properties and Critical Damage Parameters of Notched Specimens of Marine Steel

为了研究应力三轴度对船用10CrNiCu钢延性断裂的影响,分别对无缺口试样和带有不同曲率半径缺口的试样测量了其力学性能及临界损伤参数Wdc,并用扫描电镜对断口进行观察.试验结果表明:缺口试样的塑性变形集中在缺口根部很小的区域,材料强度随应力三轴度的增大而升高;在准静态加载条件下,临界损伤参数Wdc基本保持恒定,且与加载速率无关.临界断裂应变与应力三轴度满足Johnson-Cook断裂准则,即满足指数衰减关系.微观断口分析表明,随着应力三轴度的增大,韧窝尺寸逐渐增大.

In order to study the effect of stress triaxiality on the ductile fracture of marine 10CrNiCu steel,mechanical properties and critical damage parameters were measured for smooth specimen and specimens circumferentially notched with various radius,and the fracture surface was observed with scanning electron microscope.Test results show that plastic deformation of notched specimen is concentrated in a very small area at the notch root,and strength of the material increases with the increase of the stress triaxiality.Under quasi-static loading,the critical damage parameter is verified as a material constant independent of loadingrate.The critical fracture strain and stress triaxiality meets the exponential decay formula in Johnson-Cook fracture criterion.Microfracture analysis shows that the dimple size increases with the increase of stress triaxiality,which is consistent with mechanical test results.