摘要
在800℃条件下,对国产压力容器(RPV)用A508-Ⅲ钢分别进行17.5 MPa、20 MPa和27 MPa 3种载荷下的蠕变试验及部分载荷下的蠕变中断试验(20 MPa和27 MPa)。微观组织及蠕变曲线研究表明,随着蠕变时间的增加,试样内空洞及第二相粒子的体积分数近似成线性增长;由此可以推断蠕变空洞萌生、扩展及第二相粒子的粗化是造成蠕变损伤的主要原因。本研究从细观力学思路出发,结合A508-Ⅲ钢蠕变过程中微观损伤机理,通过定义无损相、空洞相和第二相粒子相组成三相复合体作为代表性体积单元,提出考虑微结构损伤及演化的K-R蠕变本构方程。通过归一化处理,最终获得反映空洞及第二相粒子演化的蠕变本构方程和损伤演化方程的形式,建立微观结构损伤与本构方程之间的内在联系。
Creep tests for domestic RPV steel, A508-Ⅲ, have been performed under three types of load, 17.5MPa, 20 MPa and 27 MPa at 800℃. Furthermore, the staged creep tests of A508-Ⅲ steel under 20 MPa and 27 MPa are carried out. The study on the microstructure and creep curve shows that the volume fractions of cavities and second phase particles increase linearly in the process of creep, so the nucleation and growth of cavities as well as second phase particles coarsening have become the main reason of creep damage. Based on mesomechanics ideas and analysis on the microscopic creep damage mechanism of A508-Ⅲ steel at 800℃, an K-R creep damage constitutive equation involved microscopic damage and its evolution is established through defining a representative volume element, which is a three-phase composite volume consists of no damage phase, cavities phase and second phase particles. By the normalization process, the creep constitutive equation and damage evolution equation reflected the evolution of cavities and the second phase particles are obtained, which set up the inner relation between micro structure damage and macroscopic constitutive equation.
出处
《核动力工程》
EI
CAS
CSCD
北大核心
2016年第5期33-39,共7页
Nuclear Power Engineering
基金
国家自然科学基金资助项目(51575489)
浙江省公益技术研究社会发展项目(2014C23001)
