EVALUATION OF EMBRITTLEMENT OF WELD METAL IN PRIMARY COOLANT CIRCUIT.

SUS 304型不锈钢的两个厚面板由SUS 308型不锈钢使用沉积弧焊接过程进行焊接。A change in the compositional and toughness of the weldmetal during aging at temperatures of 350℃ and 425℃ have been investigated by Mossbauer spectroscopy and Charpy impact testing.The width of the internal magnetic field distribution curve increased in the initial stage of aging followed by an increase in the paramagnetic absorption峰。而且，平均的内部磁场也随着衰老而增加。这些实验性结果导致了一个模糊的模糊性分裂的集合。铁矿石拆除的激活能量估计约为160- 200千焦/摩尔。衰老时间中的衰变部分的变化被两个超自然切线曲线的总和所解释。一个计算的曲线被呈现为预测在320℃的组合中的变化，由使用一个equation combined the activation energy.Charpy impact tests have been undertaken at 0弧度。由于Charpy的影响，能量被在上面的温度下测量了。按顺序计算老化时间（t）和温度（T）的综合影响，老化参数： p（T，t）=logt+0.4343（Q/R）（1/673-1/T），已引入。Charpy的影响数据被绘制为p（T，t）的一个函数，给出了Q = 125千焦/摩尔的最佳拟合值，所有实验点都落在一个主曲线上。实验数据拟合到一个hyperbolic tangent function， U = U = D20 y D2+D{1+tanh（p（T， t）-E）/F}。需要老化时间，以便Charpy的影响能下降到一半的未老化金属在320℃的基础上估计为500千瓦小时。

Two thick panels of SUS304 type stainless steel were welded by SUS308 type stainless steel using submerged arc welding process. A change in the compositional and toughness of the weldmetal during aging at temperatures of 350℃ and 425℃ have been investigated by Mossbauer spectroscopy and Charpy impact testing.The width of the internal magnetic field distribution curve increased in the initial stage of aging followed by an increase in the paramagnetic absorption peak. And also the mean internal magnetic field increased with aging time. These experimental results led to a conclusion that the ferrite undergoes spinodal decomposition. The activation energy for the ferrite decomposition was estimated to be about 160-200kJ/mol. The change in the decomposition fraction of ferrite with aging time was interpreted by the sum of two hyperbolic tangent curves. A calculated curve was presented to predict the change in the composition of ferrite during aging at 320℃ by using an equation combined the activation energy.Charpy impact tests have been undertaken at 0℃ . Reductions in the Charpy impact energy were measured by aging at the above temperatures. In order to take account of the combined effect of aging time(t) and temperature(T), an aging parameter : p(T,t)=logt+0.4343(Q/R)(1/673-1/T), was introduced. The Charpy impact data were plotted as a function of p(T,t) to give a best fit value of Q = 125kJ/mol , for which all experimental points fell on a single master curve. The experimental data were fitted to a hyperbolic tangent function, U = UィイD20ィエD2+D{1+tanh(p(T, t)-E)/F}. The aging time required for the Charpy impact energy to drop to a half of that of the unaged weldmetal was estimated as 500kh at 320℃ on the basis of the above equation.