Corrosion leaking of preheater weldment in alumina factories  

作　　者：张利 陈文汨 龚竹青 刘红召 

机构地区：[1]School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China [2]School

出　　处：《Journal of Central South University of Technology》2005年第4期443-447,共5页中南工业大学学报（英文版）

摘　　要：Stress corrosion cracking (SCC) and anticorrosion measures of TU42C weld-joint were studied by constant load experiments and pickling experiments. The results show that in 40%(mass fraction) NaOH solution at 110℃, caustic SCC occurs in TU42C weld-joints at the applied potential of-1020mV(vs SCE) for 3d while at the potential of-950mV(vs SCE) for 10d. All the cracks are intergranular. In the 10% sulfuric acid, the cracks have the most negative self-corrosion potential-432.5mV(vs SCE) and are active to be further corroded by the acid. Because of the same corrosion behaviour as the lab weldment, preheater’s cracking in alumina factories is attributed to the combining actions of previous caustic SCC in Bayer solutions and continuous acid corrosion by pickling with the addition of RD. The following measures are effective to prevent the corrosion failure of preheater, such as postweld heat treatment at 620℃ to relax the residual weld stress, addition of CC3 and L826 as the corrosion inhibitors to improve the pickling and cleaning by the high pressure water instead of by pickling.Stress corrosion cracking （SCC） and anticorrosion measures of TU42C weld-joint were studied by constant load experiments and pickling experiments. The results show that in 40% （mass fraction） NaOH solution at 110℃, caustic SCC occurs in TU42C weld-joints at the applied potential of —1020 mV（vs SCE） for 3 d while at the potential of—950 mV（vs SCE） for 10 d. All the cracks are intergranular. In the 10% sulfuric acid, the cracks have the most negative self-corrosion potential —432.5 mV（vs SCE） and are active to be further corroded by the acid. Because of the same corrosion behaviour as the lab weldment, preheater＇s cracking in alumina factories is attributed to the combining actions of previous caustic SCC in Bayer solutions and continuous acid corrosion by pickling with the addition of RD. The following measures are effective to prevent the corrosion failure of preheater, such as postweld heat treatment at 620 ℃ to relax the residual weld stress, addition of CC3 and L826 as the corrosion inhibitors to improve the pickling and cleaning by the high pressure water instead of by pickling.

关 键 词：stress corrosion crackingl constant load experimentl pickling corrosion inhibitor postweld heat treatment 

分 类 号：TG172[金属学及工艺—金属表面处理] TG174.4[金属学及工艺—金属学]