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本文研究了用小型试样作断裂韧性试验时采用电位法测定稳定裂纹扩展起始的方法。试验材料是A533B钢和KAS钢,试验是在室温和低温下,作了三点弯曲试验和紧凑拉伸试验(CT试验)。并对所测得的断裂韧性值δ_i值及J_i值的各种性能进行了研究。其主要结果如下。 1)电位变化和夹式引伸计张开位移对应关系中的拐点,就是稳定裂纹扩展起始点。 2)J_i/σ_y值和δ_i值之间有良好的对应关系。 3)利用电位法所得的δ_i值及J_i值,与用断口表面分析的R一曲线法得到的δ_i值及J_i值大体上是相同的。
In this paper, a method of measuring the onset of stable crack growth by potentiometric method in the case of small fracture toughness test is studied. The test materials are A533B steel and KAS steel. The test is a three-point bending test and a compact tensile test (CT test) at room temperature and low temperature. The measured fracture toughness δ_i and J_i values of various properties were studied. The main results are as follows. 1) The point of inflection in the correspondence between the change of potential and the extension of clip-on extensometer is the starting point of stable crack growth. 2) There is a good correspondence between the value of J_i / σ_y and the value of δ_i. 3) The δ_i values and J_i values obtained by the potential method are substantially the same as the δ_i values and the J_i values obtained from the R-curve method using the fracture surface analysis.