【摘要】 本文研究20Cr,20CrMo,34CrNi3Mo,30CrMnSiA,OCr13Ni4Mo（铸钢）等材料三点弯曲试样的开裂点。利用单试样的实验数据以计算机计算,求得开裂点,J_1c与国标多试样法结果基本一致。 本文注意到钢的硬化指数可能变化,推导了裂纹扩展量的公式,与实验结果符合良好。更多还原

【Abstract】 An analytical method for determining the initiation of crack growth in TPB specimens is developed.Several kinds of medium-high strength steel with yield strength in the range 53 kg/mm2 to 115 kg/mm2 are used to test the method.It is satisfactory in JIc determination of a single specimen when it is compared with the usual multi-specimen method.The dimensions of the specimens are B×W×L=20×24×110 mm,where B,W,L are respectively the thickness,width and the length of the specimen,With such size limitation,it is found that the steel investigated fall into different types.It is important to distinguish the plastic behavior at the crack tip before the initiation of crack growth.The analytical method developed in this paper takes account of the possible change of work hardening capacity at the crack tip region.更多还原