摘要
在某火力发电厂660MW超临界机组在役锅炉检修过程中,发现左侧水冷壁上集箱筒体外壁存在一条长达1520mm的纵向裂纹。通过光谱分析、硬度测试、金相显微组织试验和应力分析等方法结合筒体的成型工艺,对裂纹的形成原因进行分析。结果表明:集箱筒体原材料管坯经热加工成型后,在外壁形成与金属锻造流线方向一致的分层缺欠是引发裂纹的原因。集箱在后续的使用过程中,经高温、高应力工作环境服役后引起分层缺欠处夹杂物剥落和组织发生变化而形成裂纹源,随着服役时间的增加,裂纹不断扩展,由开始的沿晶开裂特征,慢慢演变成穿晶开裂特性。
It was found that there was a 1520 mm longitudinal crack in the outer wall of the upper header of the left water wall during the overhaul of the 660 MW supercritical unit’s boiler in a fossil-fuel power plant.The causes of crack formation had been analyzed by means of spectral analysis,hardness testing,metallographic examination and stress analysis combined with the forming process of the barrel.The results showed that the laminar imperfections formed in accordance with the direction of the metal forging streamline on external wall of the header after the hotworking processes were the causes of cracking.The inclusions flaking and tissue changes occurred in the laminar imperfections of the header and formed the crack source after serving in the high-temperature and high-stress working environment.With the increase of service time of the header,the crack expanded continuously and gradually evolved from the initial intergranular cracking characteristics to transgranular cracking characteristics.
作者
邓博华
王安平
梅作军
吴红辉
窦洪
Deng Bohua;Wang Anping;Mei Zuojun;Wu Honghui;Dou Hong(Guangdong Dianyan Bolier Pressure Vessel Inspection Center Co.,Ltd.,Guangzhou 510700;Chongxin Power Generation of Powerchina Gansu Energy Co.,Ltd.,Pingliang 744200)
出处
《中国特种设备安全》
2019年第8期52-56,共5页
China Special Equipment Safety
关键词
超临界机组
锅炉集箱
纵向裂纹
分层缺欠
Supercritical unit
Boiler header
Longitudinal crack
Laminar imperfections
