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本课题着重研究了“W”型小试样的J积分公式(J=(2U)/(B(W-a))-(0.3887Ue)/(B(W-a)))在测定三种核压力容器钢S271,645-3和A508-3的J_(IC)-T特性上运用的可能性。随着温度下降,J_(IC)值也下降,因而单位裂纹扩展所需的能量也下降。从试样断口上可以看到,脆性断裂所占比例相应增加,J_(IR)曲线由陡峭变得平坦。尽管这种现象对多试样J_(IR)曲线的构成是不利的,但实验证明,在压力容器钢转变温度附近仍可获得J_(IR)曲线。这就为测定在转变温度附近的J_(IC)值提供了实际依据。
This project focuses on the J integral formula of small sample “W” (J = (2U) / (B (Wa)) - (0.3887Ue) / (B (Wa))) Potential for J_ (IC) -T characteristics of container steels S271, 645-3 and A508-3. As the temperature decreases, the J_ (IC) value also decreases, so the energy required per unit crack propagation also decreases. As can be seen from the fracture surface of the specimen, the proportion of brittle fracture increases correspondingly, and the curve of J_ (IR) becomes steep and flat. Although this phenomenon is unfavorable to the composition of the multi-sample J IR curve, experiments show that the J IR curve can still be obtained near the pressure vessel steel transition temperature. This provides a practical basis for determining the J_ (IC) value near the transition temperature.