查看更多>>摘要：The radiant tube burner was modeled and analyzed by the numerical simulation method to investigate the influence factors and rules of NOx emissions in a W-type radiant tube.These factors,which include air preheating temperature,excess air coefficient,and fuel gas composition,were modified to study their effects on NOx emissions under varying working conditions.Simulation results were compared with the theoretical calculation value based on chemical reaction equilibrium theory and the onsite experimental value to verify the simulation accuracy.The results show that NOx emissions rise with increasing air preheating temperatures.NOx production increases to an extreme value and then decreases during the oxygen-poor to oxygen-enriched process with the rise of the excess air coefficient.Enhancing the proportion of coke oven gas in the fuel gas raises the combustion temperature as well as the NOx discharge.Both the thermal efficiency and NOx emissions should be balanced.Therefore,the recommended values based on the simulation results are as follows:the air preheating temperature should not exceed 400 ℃,the excess air coefficient should be between 1.1 and 1.2,and the volume fraction of the coke oven gas should not exceed 30％.
查看更多>>摘要：An internal defect meter is an instrument to detect the internal inclusion defects of cold-rolled strip steel. The detection accuracy of the equipment can be evaluated based on the similarity of the multiple detection data obtained for the same steel coil.Based on the cosine similarity model and eigenvalue matrix model,a comprehensive evaluation method to calculate the weighted average of similarity is proposed.Results show that the new method is consistent with and can even replace artificial evaluation to realize the automatic evaluation of strip defect detection results.
查看更多>>摘要：The welding interface is crucial to the service safety of dissimilar metal weld (DMW)joints between stainless steel (SS)and low alloy (LA)steel.Different status of welding interfaces was prepared by cladding SS consumables to LA steel substrates with different heat inputs via tungsten inert gas arc welding (TIG),followed by a series of microstructural characterizations and hardness tests.Results showed that a hardening and transition layer (TL)would be generated along the welding interface,and the width and hardening degree of the TL would increase with the heat input.Meanwhile,heavy load hardness tests showed that highly severe inhomogeneous plastic deformation and the microcrack would be generated in the interfacial region and the welding interface respectively in the highest heat input sample (1.03 kJ/mm).These results indicate that the increase in heat input would deteriorate the bonding performance of DMW joints.Further microstructural observations showed that the higher hardening degree of the highest heat input sample was mainly attributed to the stronger grain boundary,solution, and dislocation strengthening effects.
查看更多>>摘要：When a steel plate produced by a steel plant leaves the factory,its upper surface should be marked with the specification,variety,batch number,and other identifying information,and its side should be marked with a side marking.The side marking contains the plate number,specification,batch number,and other information,which are convenient for customers to accurately identify relevant information after stacking.However,because of the influence of weather,environment,and other factors,the side marking becomes unidentifiable when the steel plate is corroded,affecting the customer's loading,unloading,and other operations.The development and application of side anticorrosion devices and cleaning of finished heavy steel plates with antirust agents will solve the problem of unrecognizable side marking due to corrosion.
查看更多>>摘要：Controlling inner-wall band segregation is one of the difficulties in the production of high-strength antisulfur pipes.Comparative tests were carried out on different casting processes (superheat,mold electromagnetic stirring,end electromagnetic stirring,casting speed and soft reduction)for the smelting of high-strength antisulfur pipes.The microstructures of continuous-casting billets and hot-rolled or tempered pipes were analyzed using a metallographic microscope and scanning electron microscope.The mechanism and evolution law regarding the inner-wall band segregation of high-strength antisulfur pipes were studied,and the influence of different casting processes was explored.
查看更多>>摘要：The BG110E high-strength expansion pipe was developed using medium manganese steel and subjected to a two-phase zone heat treatment process.Mechanical properties and microstructure analysis results have proven that the BG110E expansion pipe exhibits uniform elongation of more than 19％.Moreover,after undergoing expan-sion deformation,its strength,toughness,and plasticity are found to meet the stringent requirements of the P110 pipe.The microstructure of this high-strength expansion pipe,which has a strength of 110 ksi (1 ksi=6.895 MPa), consists of tempered martensite,ferrite,retained austenite,and granular bainite.The propotion of retained austenite reaches up to 12％,ensuring high plasticity and the occurrence of the transformation-induced plasticity effect during the deformation process.Consequently,it enhances the coordinated deformation ability between different phases, which significantly improves the internal yield pressure of the BG110E high-strength expansion pipe in turn.
查看更多>>摘要：GH984G alloy is a significant candidate material for 650-700 ℃ ultra-supercritical coal-fired generating units.In this paper,creep rupture properties and microstructure stability of the GH984G alloy tube were studied,and the findings indicated excellent creep rupture properties at 700 ℃.Furthermore,the extrapolated strength for 100 000 h was found to be 153.8 Mpa,which satisfies the requirements for the long-term performance of high-temperature materials in power stations.Aging at 700 ℃ with the extension of time,the grain boundary carbides and the particle size of the γ' phase on the matrix gradually coarsen,but its spherical morphology remains uniformly distributed.However,no harmful phase precipitates were found even after aging at 700 ℃ for up to 19 144 h. Excellent microstructure stability guarantees the 700 ℃ creep rupture properties of the GH984G alloy tube.
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