不同镍基堆焊材料在高温高压水中的应力腐蚀行为研究

STRESS CORROSION CRACKING BEHAVIORS FOR DIFFERENT NI-BASED WELDING MATERIALS IN HIGH TEMPERATURE AND HIGH PRESSURE WATER

通过U弯浸泡实验研究了电渣焊600合金、电渣焊690合金和埋弧焊690合金三种材料的应力腐蚀行为。研究结果表明:模拟压水堆核电站一回路水化学工况,温度为325℃,压力为15.8 MPa,溶液中含1.5×10^(-3)B、2.3×10^(-6)Li、2.5×10^(-6)H_2,浸泡1193 h后,电渣焊600合金、电渣焊690合金和埋弧焊690合金样品均未发生应力腐蚀开裂。在温度为330℃,压力为11 MPa,含10 mass%NaOH的高温高压强碱溶液中,电渣焊600合金样品浸泡720 h后发生了应力腐蚀开裂,最大裂纹长度为835μm;浸泡1440 h后,裂纹进一步扩展,达到1135μm,具有典型的沿晶应力腐蚀开裂(IGSCC)特征;电渣焊690合金样品经过1440h浸泡后,表面萌生长度为0.3μm到1.15μm不等的微裂纹;埋弧焊690合金样品经过1440 h浸泡后未发生应力腐蚀开裂。

U-bend immersion tests were used for studying the stress corrosion cracking behaviors for electroslag welding （ESW） Alloy 600, electroslag welding （ESW） Alloy 690 and submerged-arc welding （SAW） Alloy 690. Results showed that electroslag welding Alloy 600, electroslag welding Alloy 690 and submerged-arc welding Alloy 690 samples were immune to stress corrosion cracking in simulated primary water of pressurized water reactor （PWR） after being immersed for 1193 h, which contained 1.5×10-3 , 2.3×10-6 Li, 2.5×10-6 H2 at 325℃, 15.8 MPa. However, stress corrosion cracks were observed in eleetroslag welding Alloy 600 after being immersed in 10 wt.% NaOH alkali solution for 720 h at 330 ℃, 11 MPa. The maximum crack length was 835 pm after 720 h immersion and further expanded to 1135μm after 1440 h immersion with a typical intergranular stress corrosion cracking （IGSCC） characteristic. For eleetroslag welding Alloy 690, mierocraeks were initiated with the length of 0.3 μm to 1.15μm and stress corrosion crack was not observed.