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针对换热管腐蚀泄漏问题,采用金相、扫描电镜、能谱等技术对换热管的腐蚀形貌、腐蚀产物成分进行分析。结果表明:换热管内冷却介质中高含量的氨氮对换热管应力腐蚀开裂起主要作用;管子端部与管板的胀接,使其胀管与未胀过渡区留下了较大的残余应力;换热管选用的HAl77-2铝黄铜管也不适合在含有很高氨氮介质的环境中使用。因此,在腐蚀介质、残余应力、敏感材料三个条件都具备的情况下,换热管短期内发生应力腐蚀开裂而泄漏失效。
Aiming at the problem of corrosion and leakage of heat exchange tubes, the corrosion morphology and composition of corrosion products were analyzed by metallographic, scanning electron microscope and energy spectrum techniques. The results show that the high content of ammonia nitrogen in the cooling medium plays a major role in the stress corrosion cracking of the heat exchange tube. The expansion of the tube end to the tube plate leaves a large residual stress ; Heat pipe selection HAl77-2 aluminum brass is not suitable for use in high ammonia nitrogen medium environment. Therefore, corrosion medium, residual stress, sensitive materials are three conditions are available, the heat transfer tube short-term stress corrosion cracking and leakage failure.