余热锅炉过热器管焊缝开裂原因分析

Cracking reasons analysis of superheater tubes of a waste heat boiler

针对某电厂一台余热锅炉煮炉后试运行期间出现了过热器管焊缝开裂的问题,取样开展了宏观检查、化学成分分析、硬度测试、金相组织检验及能谱分析等试验,结合管道布置结构等,对焊缝开裂原因进行了分析。结果表明,锅炉结构及焊接工艺不当引起了焊缝位置较高的应力,且煮炉过程控制不当,导致碱液进入了过热器管并浓缩,最终在温度、应力和碱液的共同作用下导致了焊接接头苛性脆化开裂。并针对开裂原因提出了建议。

To solve the problem of some weld cracks appeared on the superheater tubes of a waste heat boiler during the trial operating, a series of experiments were carried out,such as macroscopic inspection,chemical composition analysis,hardness test,metallographic structure inspection and energy spectrum analysis,etc.. Based on the experimental results and tubeline arrangement, the reasons for weld cracking were analyzed. The result shows that the caustic embrittlement of welded joints occurred under the action of temperature, stress and alkali solution, which was due to the improper structure and welding process of the boiler cause high stress to the welded joint,and the improper control of the boiler boiling process caused the alkali liquid to flow into the superheater and concentrate. In this paper, some suggestions are also given for the reasons of weld cracking.