高温模拟压水堆一回路水中SO<sub>4</sub><sup>2-</sup>对690TT镍基合金SCC敏感性的影响

高温模拟压水堆一回路水中SO₄^2-对690TT镍基合金SCC敏感性的影响

摘要: 采用慢应变速率试验(SSRT)研究了310℃模拟压水堆一回路水中硫酸根离子(SO₄^2-)含量对690TT镍基合金应力腐蚀开裂(SCC)敏感性的影响。结果表明:690TT镍基合金试样的断口附近均出现了颈缩,在SO₄^2-含量较低的模拟压水堆一回路水中,690TT镍基合金试样断口大多呈剪切状,应力腐蚀敏感性低;当SO₄^2-质量分数达到1 500 μg/kg时,断口边缘局部出现穿晶裂纹,高含量的SO₄^2-使690TT镍基合金的应力腐蚀开裂敏感性提高。

Abstract: The effect of SO₄^2- concentration on stress corrosion cracking (SCC) susceptibility of nickel-based alloy 690TT in simulated pressurized water reactor (PWR) primary water was investigated by slow strain rate testing (SSRT) at 310 ℃. The results show that necking occurred near the fracture of the nickel-based alloy 690TT samples. In the PWR primary water containing low concentration of SO₄^2-, most fractures of the nickel-based alloy 690TT samples were shear-like, and the stress corrosion susceptibility of the alloy was low. When the mass fraction of SO₄^2- reached 1 500 μg/kg, transgranular cracks occurred at the localized zones of fracture edge, which means high concentration of SO₄^2- increased the SCC susceptibility of nickel-based alloy 690TT.