摘要
Abstract
The corrosive medium generated by coal-fired power boilers during operation will form oxide scale and corrosion products on the surface of welding joints,resulting in a decrease in joint strength.To improve the quality of welding joints in coal-fired power generation boilers and reduce the corrosion rate of welding joints,laser TIG composite welding technology and corrosion performance test analysis were conducted for coal-fired power generation boilers.The new type of ferritic heat-resistant steel SA213-T23 was selected.The laser-TIG composite welding process was adopted,with YAG solid-state pulsed laser and paraxial TIG arc as the heat sources.The laser power was set at 300W,350W,400W and 450W respectively for welding.After the welding was completed,the basic mechanical properties and corrosion resistance of the specimens were tested.The results show that moderately increasing the laser power can improve the joint strength,and the basic mechanical properties of the weld reach the optimal level at 400W.Furthermore,for the welded specimens obtained at this laser power in electrochemical corrosion,intergranular corrosion and immersion-corrosion tests in different media,the specimen presents the highest corrosion potential and the lowest corrosion current,with its self-corrosion current,self-corrosion potential and passivation current superior to those of specimens welded at other power levels.Meanwhile,its mass loss is minimal and no cracks occur after bending.During the soaking process in H2SO4 and NaOH solutions of different mass fractions,the corrosion rate of the 400W specimens remained the lowest all the time.Therefore,when the welding laser power is 400W,the quality of the welded joints of coal-fired power generation boilers can be effectively guaranteed.关键词
燃煤发电锅炉/复合焊接/腐蚀性能/激光功率/腐蚀电流/腐蚀电位Key words
coal-fired power generation boiler/composite welding/corrosion performance/laser power/corrosion current/corrosion potential
