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从10座电站调查证实,电站中非直接受热的锅炉承压元件的实际损坏类型绝大多数均具有局部蠕变开裂特征或局部应力腐蚀开裂特征,这两种破坏仅仅发生在应力集中部位。调查中未见到一次膜应力控制的破坏(错用钢材者除外),也未见由启停机次数较多引起的低周疲劳破坏,仅见少数断口具有疲劳特征的热疲劳破坏。 为了保证电站锅炉承压元件的安全运行,设计规范中必须有防止局部蠕变开裂和局部应力腐蚀开裂的相应规定。
Investigation from 10 power stations confirmed that most of the actual types of damage to the pressure-bearing components of boilers that are not directly heated in the power station are characterized by local creep cracking or local stress corrosion cracking, both of which occur only in the site of stress concentration. No damage to membrane stress control was observed during the investigation (except for those who misused steel), and no low-cycle fatigue failure caused by a high number of start-stop operations was observed. Only a few thermal fatigue failures with fatigue characteristics at the fracture surface were observed. In order to ensure the safe operation of power plant boiler pressure components, there must be provisions in the design code to prevent local creep cracking and local stress corrosion cracking.