SA543钢在高温锅炉水中的应力腐蚀性能试验研究

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To solve the stress corrosion crack（SCC） problem of Ethylene Oxide（EO） reactors in the boiler feed water containing Na3PO4 of a company,the stress corrosion cracking of SA543 steel in the boiler feed water containing Na3PO4 and improved boiler feed water containing（NH4） 3PO4 were investigated by using stress corrosion tests with pre-cracked wedge-open loading（WOL） specimens and slow strain rate tests（SSRT）.The results of WOL tests show that the stress corrosion crack growth rate of SA543 steel is nearly zero in the improved boiler feed water at 100 ℃;the SSRT tests find that sensitivity index of SA543 steel to stress corrosion at the 260 ℃ boiler feed water containing Na3PO4 is comparatively high,which has certain stress corrosion tendency;while the sensitivities indexes of SA543 steel in the boiler feed water containing（NH4） 3PO4 are slightly lower than 25% without stress corrosion tendency.The experimental results implies the resistance to SCC initiation and propagation of SA543 steel significantly increases in the improved boiler feed water,which provide some technical supports for safety assessment of Ethylene Oxide reactors.针对某公司乙二醇装置R-110/R-120环氧乙烷反应器在含磷酸钠锅炉水中出现的应力腐蚀裂纹问题,通过楔形张开加载（WOL）预裂纹试样应力腐蚀试验和慢应变速率试验,研究SA543钢在含Na3PO4锅炉水和改进后含（NH4）3PO4锅炉水中的应力腐蚀开裂行为。楔形张开加载预裂纹试样应力腐蚀试验结果表明,SA543钢在100℃的锅炉水中应力腐蚀裂纹扩展速率几乎为零;慢应变速率试验发现SA543钢在260℃下含Na3PO4的锅炉水环境中的应力腐蚀敏感性指数较大,有应力腐蚀倾向;而在含（NH4）3PO4锅炉水中的应力腐蚀敏感性指数均小于25,没有应力腐蚀倾向。说明在改进后的高温锅炉水中,SA543钢应力腐蚀裂纹萌生和扩展的抗力明显增强,为环氧乙烷反应器缺陷的安全评定提供了数据支撑。