某超临界锅炉螺旋管圈水冷壁开裂原因分析  

Causes Analysis on Cracking of Water Cooled Wall of Spiral Tube in A Supercritical Boiler

作　　者：蒋涛 JIANG Tao(Datang Northeast Electric Power Test and Research Institute,Changchun 130012,China)

机构地区：[1]大唐东北电力试验研究院有限公司,吉林长春130012

出　　处：《热加工工艺》2023年第5期158-162,共5页Hot Working Technology

摘　　要：某超临界锅炉在检查中发现螺旋管圈水冷壁发生开裂泄漏,通过现场检查、宏观分析、微观分析、化学成分分析、金相组织以及硬度分析等方法,综合判断水冷壁开裂的原因。结果表明:开裂位置焊缝组织中粒状贝氏体具有粗大原奥氏体晶界,针状铁素体细小,焊缝主裂纹沿原奥氏体晶界扩展,呈沿晶开裂特征;不合理的构件布置及较差的焊接质量是焊缝开裂的根本原因,气孔和夹渣等焊接缺陷为裂纹源,在拘束应力、自身重力、焊接应力、锅炉膨胀应力和张力板传递载荷的多重作用下,致使裂纹扩展。为防止发生类似事故,提出了相应的预防措施。The water cooled wall of a spiral tube cracked and leaked during the inspection of a supercritical boiler.The causes of water cooled wall cracking were comprehensively determined through on-site inspection,macroscopic analysis,microscopic analysis,chemical composition analysis,metallographic structure analysis and hardness analysis.The results show that the granular bainite has coarse pre-austenite grain boundary,and the acicular ferrite is fine in weld structure at cracking position.The main crack in the weld expands along the pre-austenite grain boundaries,showing intergranular cracking characteristics.Unreasonable component layout and poor welding quality are the root causes of weld cracking.The welding defects such as pores and slag inclusions are the source of cracks,and it leads to crack propagation under the multiple action of constraint stress,self-gravity,welding stress,boiler expansion stress and load transmitted by the tension plate.In order to prevent similar accidents,the corresponding preventive measures were proposed.

关 键 词：超临界锅炉 螺旋管圈 水冷壁 开裂 应力 

分 类 号：TG441.7[金属学及工艺—焊接]