Aiming at the high temperature corrosion in a coal-fired boiler,the effect of H2S and SO2 on the corrosion of 12 CrlMoV under the water wall condition has been investigated by experiments.The results indicate that H2 ...Aiming at the high temperature corrosion in a coal-fired boiler,the effect of H2S and SO2 on the corrosion of 12 CrlMoV under the water wall condition has been investigated by experiments.The results indicate that H2 S can promote the corrosion significantly,and the coarse porous oxide film formed cannot stop the progress of corrosion.While SO2 presents little effect on the corrosion.The main composition of the surface of 12 CrlMoV corrosion products is Fe2 O3.With H2S in the atmosphere,the corrosion gradually develops into deeper layers by forming FeS,FeO and Fe2 O3 alternately.The corrosion rate is doubled for every 50℃ inerease in temperature at 400-500℃.展开更多
Shrinkage cavities and large inclusions are serious internal defects of heavy steel ingot and influence the quality of subsequent forgings. In order to remove these two types of defects, a 70 t 12Cr2Mo1 heavy ingot fa...Shrinkage cavities and large inclusions are serious internal defects of heavy steel ingot and influence the quality of subsequent forgings. In order to remove these two types of defects, a 70 t 12Cr2Mo1 heavy ingot fabricated by vacuum carbon de-oxidation process was sectioned and investigated by means of structure observation and EDS analysis. To further study the forming mechanism of shrinkage and inclusion defects and find possible solutions, simulation on pouring and solidification processes was also carried out using Fluent and ProCAST software, respectively. Results show that the shrinkage defects do not appear in the middle-upper part of the ingot. The critical value of shrinkage cavity criterion is ascertained as 0.013 on the basis of sectioning investigation and simulation results, which can be used in computer simulation to predict and avoid shrinkage defects in production of 12Cr2Mo1 ingots with different weights. However, large inclusions are found at the bottom of the ingot body. The bad thermal conditions of the ingot surface and large amount of entrained slag are the main origin of the large inclusions. The simulation result of the pouring process shows that large inclusions may be eliminated by combined measures of improving the top thermal condition and controlling the height of rudimental molten steel in the ladle to above 300 mm.展开更多
12Cr2Mo1VR钢板生产的流程为100 t EAF-LF-VOD-CC-ESR-轧制工艺。电渣重熔过程中,采用熔速降低(160~180)kg/h及氮气保护等工艺;轧制过程采用低速大压下量轧制工艺;轧后采用650~700℃长时保温扩氢退火工艺;热处理采用930-950℃正火(加速...12Cr2Mo1VR钢板生产的流程为100 t EAF-LF-VOD-CC-ESR-轧制工艺。电渣重熔过程中,采用熔速降低(160~180)kg/h及氮气保护等工艺;轧制过程采用低速大压下量轧制工艺;轧后采用650~700℃长时保温扩氢退火工艺;热处理采用930-950℃正火(加速冷却)+680-700℃回火工艺。生产的钢板表面质量良好,探伤级别满足NB/T47013.3-2015及第1号修改单TⅠ级要求,钢板成分、显微组织均匀,力学性能满足技术要求。展开更多
基金supported by the National Key Research and Development Plan of China (No. 2018YFB0604203)
文摘Aiming at the high temperature corrosion in a coal-fired boiler,the effect of H2S and SO2 on the corrosion of 12 CrlMoV under the water wall condition has been investigated by experiments.The results indicate that H2 S can promote the corrosion significantly,and the coarse porous oxide film formed cannot stop the progress of corrosion.While SO2 presents little effect on the corrosion.The main composition of the surface of 12 CrlMoV corrosion products is Fe2 O3.With H2S in the atmosphere,the corrosion gradually develops into deeper layers by forming FeS,FeO and Fe2 O3 alternately.The corrosion rate is doubled for every 50℃ inerease in temperature at 400-500℃.
基金financially supported by the Program of National Technological Cooperation and Communication(Project 2010 DFR 70640)Chinese National S&T Major Project(2011ZX06004-016)
文摘Shrinkage cavities and large inclusions are serious internal defects of heavy steel ingot and influence the quality of subsequent forgings. In order to remove these two types of defects, a 70 t 12Cr2Mo1 heavy ingot fabricated by vacuum carbon de-oxidation process was sectioned and investigated by means of structure observation and EDS analysis. To further study the forming mechanism of shrinkage and inclusion defects and find possible solutions, simulation on pouring and solidification processes was also carried out using Fluent and ProCAST software, respectively. Results show that the shrinkage defects do not appear in the middle-upper part of the ingot. The critical value of shrinkage cavity criterion is ascertained as 0.013 on the basis of sectioning investigation and simulation results, which can be used in computer simulation to predict and avoid shrinkage defects in production of 12Cr2Mo1 ingots with different weights. However, large inclusions are found at the bottom of the ingot body. The bad thermal conditions of the ingot surface and large amount of entrained slag are the main origin of the large inclusions. The simulation result of the pouring process shows that large inclusions may be eliminated by combined measures of improving the top thermal condition and controlling the height of rudimental molten steel in the ladle to above 300 mm.
文摘12Cr2Mo1VR钢板生产的流程为100 t EAF-LF-VOD-CC-ESR-轧制工艺。电渣重熔过程中,采用熔速降低(160~180)kg/h及氮气保护等工艺;轧制过程采用低速大压下量轧制工艺;轧后采用650~700℃长时保温扩氢退火工艺;热处理采用930-950℃正火(加速冷却)+680-700℃回火工艺。生产的钢板表面质量良好,探伤级别满足NB/T47013.3-2015及第1号修改单TⅠ级要求,钢板成分、显微组织均匀,力学性能满足技术要求。
