【摘要】 在模拟压水堆一回路水化学环境(325℃、15.5 MPa、1.2 mg·L^-1硼、2.2μg·L^-1锂、2 mg·L^-1溶解氧或1.6 mg·L^-1溶解氢)中，采用应力腐蚀裂纹扩展速率在线测量技术，通过裂纹扩展试验对比研究了压水堆某阀门用国产和进口690镍基合金的应力腐蚀裂纹扩展行为。结果表明：国产690合金和进口690合金内部残余应变均低于10%，在模拟压水堆一回路工况下的裂纹扩展速率均处于10^-9 mm·s^-1数量级，2种合金均具有较低的应力腐蚀开裂敏感性，这与合金中较高的铬含量有关。与进口合金相比，国产690合金的晶粒尺寸较大，Σ3孪晶界占比较高，晶界的位错密度和残余应变水平较低，裂纹扩展速率略低，抗应力腐蚀开裂性能较好；国产690合金的裂纹扩展以穿晶模式为主，而进口合金则呈现明显的沿晶-穿晶混合特征。国产和进口690合金的裂纹扩展速率与应力强度因子呈幂指数关系，国产690合金在不同溶解氧浓度环境中的裂纹扩展速率均较低，溶解氧对其应力腐蚀开裂行为的影响不显著。更多还原

【Abstract】 In the simulated chemical environment of the primary circuit water in the pressurized water reactor(325 ℃,15.5 MPa,1.2 mg·L^-1 B,2.2 μg·L^-1 Li,2 mg·L^-1 dissolved oxygen or 1.6 mg·L^-1 dissolved hydrogen),the stress corrosion crack growth behavior of domestic and imported 690 nickel-based alloys used in a valve of a pressurized water reactor was comparatively studied by crack growth tests based on the online measurement technology of stress corrosion crack growth rate. The results show that the internal residual strain of both domestic and imported 690 alloys was less than 10%,and the crack growth rates under the simulated primary circuit conditions of pressurized water reactors were at the order of 10^-9 mm·s^-1. Both alloys had a relatively low sensitivity to stress corrosion cracking,which was related to the high Cr content in the alloys. Compared with those of the imported alloy,the grain size of domestic 690 alloy was relatively large with a high proportion of Σ3 twin boundaries,and the dislocation density and residual strain level at the grain boundaries were relatively low;the crack growth rate of domestic 690 alloy was relatively low,and the resistance to stress corrosion cracking was better. The crack growth of the domestic 690 alloy was mainly transgranular mode,and that of the imported alloy showed obvious intergranular and transgranular mixed characteristics. The crack growth rate of domestic and imported 690 alloys was in a power-exponential relationship with the stress intensity factor. Moreover,the crack growth rate of the domestic 690 alloy was relatively low in environments with different dissolved oxygen concentrations,and the effect of dissolved oxygen on the stress corrosion cracking behavior was not significant.更多还原