Page 126 - 机械工程材料2024年第十一期

李国强，等：基于多温度SDFF模型的反应堆压力容器钢韧脆转变区韧性评价

Toughness Evaluation in Ductile-to-Brittle Region of Reactor Pressure Vessel
Steel Based on Multi-temperature SDFF Model

LI Guoqiang , YU Haibing , WU Yuanjun 2
1
1
(1. Guangxi Fangchenggang Nuclear Power Co., Ltd., Fangchenggang 538001, China; 2. Applied Mechanics and
Structure Safety Key Laboratory of Sichuan Province, School of Mechanics and Aerospace Engineering,
Southwest Jiaotong University, Chengdu 610031, China)

Abstract: The parameter calibration for a strain-energy-density-based fracture failure (SDFF) model was
improved by a maximum likelihood estimation method, and the multi-temperature SDFF model whose parameters could
be calibrated by the fracture toughness test data at different temperatures was established. The model parameters were
calculated with low-temperature fracture toughness test results of a one-inch thick compact tension (1T CT) specimen
and a 0.5-inch thick compact tension (0.5T CT) specimen sampled from reactor pressure vessel (RPV) steel. The ductile-
brittle transition temperatures of the two specimens were predicted, and the lower boundary lines of fracture toughness
were analyzed. The results show that the ductile-to-brittle transition temperatures of the 0.5T CT specimen and 1T CT
specimen calculated by the multi-temperature SDFF model were −81 ℃ and −64 ℃, respectively, and the calculated
results were in good agreement with the test results with a relative error about 6%. The fracture toughness data measured
at −90 ℃ to 20 ℃ were all within the 5% to 95% failure probability envelope, and the model had good adaptability to
specimens of different size from −90 ℃ to normal temperature. When the 0.5T CT specimen was used to analyze the
fracture toughness of the material in the ductile-brittle transition zone, with whose 5% fracture failure probability curve
as the lower boundary line of fracture toughness could cover all the test data of 0.5T CT specimen and 1T CT specimen,
and the margin was small; the margin with the 1% fracture failure probability curve as the lower boundary line of fracture
toughness was larger.
Key words: RPV steel; ductile-to-brittle transition region; maximum likelihood estimation; SDFF model;
fracture toughness

118