谈建平
,
王国珍
,
轩福贞
,
涂善东
机械工程材料
研究了紧凑拉伸（CT）试样厚度对25Cr2NiMolV钢在566℃时，蠕变裂纹扩展（CCG）速率的影响规律及其机理。结果表明：试样厚度对CCG速率的影响与载荷水平（C＊）相关；在低载荷水平区，随试样厚度的增加，面外拘束水平增大，试样趋向于以沿晶蠕变脆性方式断裂，CCG速率增大；在高载荷水平区，不同厚度的试样均以沿晶和穿晶的混合方式发生蠕变延性断裂，CCG速率基本不受试样厚度的影响；CCG速率与载荷水平在双对数坐标中并非呈单一的线性关系，而是由不同斜率的两段直线构成，低载荷水平区的直线斜率低于高载荷水平区的，如果用高载荷水平区的CCG速率数据外推得到低载荷水平区的CCG速率，将得到非保守的结果。
关键词:
蠕变裂纹扩展
,
试样厚度
,
蠕变断裂机理
,
载荷水平
,
拘束效应
何滨
,
刘军
,
陈建恩
,
葛为民
,
王肖锋
材料导报
doi:10.11896/j.issn.1005-023X.2016.16.031
基于蠕变损伤力学,仿真了蠕变裂纹扩展过程.用ABAQUS软件模拟研究了试样几何形状和宽度不同的两种面内拘束条件对P92钢在650℃时蠕变裂纹扩展(CCG)速率的影响,并进行了试验验证.仿真结果表明:试样几何形状和宽度对CCG速率的影响与载荷水平(C*)有关;在低载荷水平区内,C(T)试样的拘束水平大于SEN(T)试样,并且对应的CCG速率较大;在中载荷水平区,随着试样宽度的增大,裂纹尖端拘束和CCG速率增大;在高载荷水平区,CCG速率基本不受面内拘束(试样几何形状、宽度)条件的影响;在条件相同的情况下,试样宽度拘束水平大于试样几何形状.试验结果表明,试验与有限元分析(FEA)的蠕变裂纹扩展结果相符合.
关键词:
蠕变裂纹扩展
,
拘束条件
,
载荷水平
,
P92钢
F.Z.Shen
金属学报(英文版)
It is showed after the furnace tubes serviced for 8-10 years that the density of damage in the HAZ (heat affected zone) of the weld has higher than in parent metals, though the depth of damage is not equal to. By the test of creep crack growth, it is also acquired that under same mechanic parameter C* (t), the rate of creep crack growth in the HAZ is more than twice as fast as in parent metals. Two mechanisms (overheating and thermal shock) of failure occurred in an accident are presented. The stress of thermal shock is analyzed, in which the change of the elasticity modulus with the radius ET=f(r) is considered. Based on it, the safety region of the thermal shock is obtained. Finally, two sets of curves for the safe life are suggested which can facilitate to estimate the remainina life of HK-40 or HP-Nb tubes by their creep rupture data.
关键词:
failure
,
null
,
null
