| Blast Furnace Top Gas Recovery Turbine Unit is a secondary energy recovery device(TRT for short).Its core component,TRT blade,operates at a very high speed in an environment containing a large number of furnace dust particles.The high frequency and high speed impact of furnace dust particles on blades is an important cause of blade surface fatigue failure.In this paper,laser surface alloying technology was used to strengthen TRT blades,so as to improve the surface erosion resistance and prolong the working life of the blades.The gas-solid two-phase flow in TRT unit was simulated numerically by ANSYS software.Firstly,according to the basic theory of fluid-solid coupling,a finite element analysis model of gas-solid two-phase flow in TRT device was established to simulate and solve the pressure load caused by particle impact on blade,erosion stress under pressure load,stress value under the coupling of erosion stress and centrifugal force,Angle value and velocity value of particle impact on blade.Based on the values obtained in the flow field,the Explicit Dynamic module was used to simulate the process of a single particle impacting the uncoated blade and Fe-Cr-W-V,Fe-Cr-Ni coated blade at different angles,and the instantaneous deformation and stress of the blade were analyzed.Fe-Cr-W-V and Fe-Cr-Ni Fe-base alloy powders were used as surface alloying powder materials,and a strengthening scheme of adding ceramic hard phase and graphite phase to the metal powders was designed.The microstructure and microhardness of the alloyed samples were analyzed,and the crystal morphology of the samples at the bottom,middle and top of the coating was analyzed.The formation reasons of the crystals were described.The compounds in the coating of the alloyed samples were determined by XRD phase analysis combined with EDS element detection.The microhardness and macro-hardness of alloyed specimens were compared,and the mechanism of the variation of hardness was analyzed.The results show that the grain sizes of the four kinds of alloyed samples are refined to different degrees,among which,after adding graphite phase C3N4 to Fe-Cr-W-V powder,acicular crystals appear on the top of the coating,and new hard phases such as VC and V8C7 are formed in the coating,with microhardness up to 800HV0.5.After adding WC ceramic hard phase to Fe-Cr-Ni powder,the grain size of the coating decreases significantly compared with that of Fe-Cr-Ni sample.The hard phases of Cr23C6 and WC appear in the coating,and the microhardness reaches 590HV0.5.The properties of alloyed specimens were compared and analyzed.Firstly,the friction and wear properties of the samples were tested,and the friction coefficient and wear amount of the alloyed samples were compared and analyzed.Among them,the friction coefficient of Fe-Cr-Ni+WC sample was the lowest,less than 0.16,and the wear resistance of Fe-CrW-V+C3N4 sample was the best,with the relative wear resistance reaching 0.68.The wear morphology and wear mechanism of the samples were analyzed in detail.Secondly,the corrosion resistance of each alloyed sample was tested,and the quality of the sample was compared before and after the experiment,and the micromorphology of the sample after the experiment was observed,and the corrosion mechanism of the sample was explained.Finally,the erosion resistance of the sample was compared and analyzed.The poor quality of the sample was taken as the index to evaluate the erosion resistance.The surface of the sample was observed by electron microscope after the experiment,and the erosion resistance mechanism of the sample was discussed.The results show that Fe-Cr-Ni+WC samples have higher hardness,better wear resistance,excellent corrosion resistance and erosion resistance. |
PDF Full Text Request