【作者】 严志刚； 俞树荣； 梁瑞； 李淑欣； 陈剑虹；

【Author】 Yan ZhiGang~1 Yu ShuRong~2 Liang Rui~2 Li ShuXin~2 Cheng JianHong~2 (1.Nanchang Hangkong University Jiangxi Nanchang 330063 2.Lanzhou University of Technology Gansu,Lanzhou 730050)

【机构】 南昌航空大学； 兰州理工大学；

【摘要】 通过对铁素体晶粒尺寸不同的两种低合金钢COD裂纹试样断裂韧性的测试,对铁素体晶粒尺寸对裂纹试样断裂韧性的影响及其机理进行了研究。结果表明:在裂纹试件中,临界事件是铁素体尺寸的微裂纹扩展进入周围的基体中。韧性值的波动是由于预裂纹长度的不同及纤维裂纹在扩展过程中,其尖端宽度的随几分布和材料中薄弱环节的随机分布引起的。韧-脆转变的主要因素为纤维扩展其前端三向应力和最大正应力上升并超过临界值,最终引发解理断裂。更多还原

【Abstract】 The fracture toughness COD of pre-cracked specimens for two alloy steels with the different sizes of ferrite grain is measured to investigate effect of size of ferrite grain on cracked fracture toughness and its mechanism.Combined with the observations of configuration changes and fracture surfaces of pre-crack tips,the results show that in pre-cracked specimens,critical event is that micro crack grows in vicinity region.Fluctuation of fracture toughness is induced by different pre-crack sizes and scatter of both crack width and inherent defects in material.The main reason of ductile-to-brittle transition is that stress triaxiality and max normal stress in crack tip exceed critical value,which leads to cleavage fracture.更多还原