氧化铝分解槽焊缝应力-碱脆开裂行为  

Stress Alkali Embrittlement Cracking Behavior of Welds in Alumina Decomposition Tank

作　　者：魏玉伟 彭安校 苏兰林 鞠成伟 梁圣钊 陆杰 李卫超 王小林 王毅 WEI Yuwei;PENG Anxiao;SU Lanlin;JU Chengwei;LIANG Shengzhao;LU Jie;LI Weichao;WANG Xiaolin;WANG Yi(Guangxi Special Equipment Inspection and Research Institute,Nanning 530200,China;Guangxi Branch Company of Aluminum Corporation of China Limited,Pingguo 531499,China)

机构地区：[1]广西壮族自治区特种设备检验研究院,南宁530200 [2]中国铝业广西分公司,广西平果531499

出　　处：《有色金属工程》2022年第7期57-67,共11页Nonferrous Metals Engineering

摘　　要：拜耳法生产氧化铝分解槽焊缝及附近出现大批次开裂,利用扫描电子显微镜(SEM)、光学显微镜(OM)等手段分析裂纹形貌和金相组织,利用有限元等方法分析分解槽罐体受力情况,最后综合分析开裂失效行为机理。结果表明:厚壁焊缝自身产生纵向、横向和厚度方向三种焊接残余应力,与罐体内部液体自重产生的应力叠加形成碱脆的多重应力环境。另外,潮湿的焊条在焊接时,在高温下分解的水蒸气会在焊缝中产生气孔,气孔造成应力集中,作为裂纹源在碱应力促进下沿晶界和珠光体区域扩展(IGPSCC)形成最终裂纹,造成泄露。最后,建立了多应力碱性环境下含气孔的厚壁容器焊缝应变诱发-阳极溶解导致的IGPSCC模型,为研究长期运行后的拜耳法氧化铝分解槽焊缝应力-碱脆开裂行为提供借鉴。Cracks appear in and around a large batch of welds of alumina decomposition tank produced in production of alumina by Bayer process.The crack morphology and metallographic structure are characterized by means of Scanning Electron Microscope(SEM)and Optical Microscope(OM),the stress of decomposition tank body is analyzed by means of finite element,and finally the failure mechanism is comprehensively analyzed.The results show that there are three residual stresses in the longitudinal,transverse and thickness directions of the thick wall weld,which are superimposed with the stresses generated by the liquid self-weight in the tank to form an alkali brittle multiple stress environment.In addition,when wet electrodes are welded,water vapor produces bubbles at high temperature.As a crack source,bubbles expand along grain boundaries(IGPSCC)under the promotion of alkaline stress to form final cracks,resulting in leakage.The IGPSCC model of multi stress thick wall weld with pores under strain anodic dissolution is established,which provides a reference for studying the stress alkali embrittlement cracking behavior of Bayer alumina decomposition tank after long-term operation.

关 键 词：拜耳法 焊缝 IGPSCC 碱脆 

分 类 号：TG171[金属学及工艺—金属表面处理]