服役2900 h的HR3C受热面管失效原因分析  

Analysis of failure causes of HR3C heating surface tubes in service for 2900 h

作　　者：刘献良 夏福庆 张国栋[1] 夏咸喜 LIU Xianliang;XIA Fuqing;ZHANG Guodong

机构地区：[1]苏州热工研究院有限公司,江苏苏州215004 [2]华能宁夏大坝电厂四期发电有限公司,宁夏青铜峡751607

出　　处：《电力科技与环保》2021年第6期57-62,共6页Electric Power Technology and Environmental Protection

基　　金：国家重点研发计划“超期服役承压设备寿命预测及延寿关键技术研究”(2016YFC0801905)。

摘　　要：为了研究某660 MW火电锅炉末级再热器管失效的原因,对失效管进行了宏观检查、化学成分分析、力学性能测试、金相组织检验及断口分析等试验。结果表明:爆口管爆口张开较大,开口长度约200 mm,爆口一侧吹损减薄,边缘锋利,另一侧无明显减薄,边缘粗糙;断口截面由减薄侧向无减薄侧形成放射扩展线;材质HR3C开裂管化学成分C,Si,Mn,P,S含量符合ASME SA-213的标准要求;硬度及室温时拉伸性能R_(m)(772 MPa)、R_(p0.2)(373 MPa)符合ASME SA-213的标准要求;高温(650℃)时拉伸性能R_(m)(482 MPa)、R_(p0.2)(212 MPa)符合GB/T 5310-2017标准要求,但室温和高温(650℃)拉伸试样断口及爆口均以沿晶脆断为主,且压扁试验中,试样出现开裂,反映出失效管子具有较大的脆性;镍基合金焊材的选用符合焊接要求。管子固定块焊缝熔合区存在咬边、未熔合等焊接缺陷,且焊趾处过渡不光滑。裂纹优先在脆性较大的HR3C材质的管子与固定块焊接的焊趾处形成,裂纹穿透管壁后高压蒸汽溢出,对临近的Super304H管子造成了吹损,导致后者减薄爆管。针对上述问题,从焊接质量、监督运行方面给出了具体的建议措施。In view of the failure of the final reheater tube of a 660 MW thermal power boiler,macro inspection,chemical composition analysis,mechanical performance test,metallographic inspection and fracture analysis were carried out on the failure tube sampling.The results show that the burst opening is larger,the length of the burst opening is about 200 mm.The blow loss on one side of the blast hole is thinned,and the edge is blade-shaped,and the other side has no obvious thinning,and the edge is rough;the fracture section forms a radial expansion line from the thinned side to the non-thinned side.The chemical composition C,Si,Mn,P,S content of the failed HR3C pipe meets the requirements of ASME SA-213.The hardness value,and tensile properties of R_(m)(772 MPa)and R_(p0.2)(373 MPa)at room temperature of the HR3C tube that failed first meet the requirements of the ASME SA-213 standard;the tensile properties of R_(m)(482 MPa)and R_(p0.2)(212 MPa)at high temperature(650℃)meet the requirements of GB/T 5310-2017 standard requirements.The fracture of the tensile specimen at room temperature and high temperature(650°C)and the blast hole are mainly intergranular fracture,and the sample cracked during the flattening test,reflecting the greater brittleness of the failed tube.At the same time,the nickel-based alloy welding consumables also meets the welding requirements.There are welding defects such as undercut and unfused seam in the welding seam of the fixed block of the pipe,and the transition of the weld toe is not smooth.The cracks are preferentially formed at the weld toe between the brittle HR3C tube and the fixed block.After the crack penetrates the tube wall,the high-pressure steam overflows,causing blow damage to the adjacent Super 304H tube,causing the Super 304H tube to thin and burst.In response to the above problems,specific recommendations are given in terms of welding quality and supervision of operation.

关 键 词：HR3C钢 TP310HCbN 再热器管 爆管 材料脆化 焊接缺陷 

分 类 号：TK175[动力工程及工程热物理—热能工程]