| The characteristics of ultra-supercritical power generation technology with high efficiency,energy saving and environmental protection are important technical ways to solve the high emission and low coal combustion utilization rate of thermal power generation.According to statistics,every 10°C increase in steam temperature increases thermal efficiency by 0.5%.At present,my country has begun to build a 630 ? demonstration power station,the biggest problem facing is the selection of materials and engineering application of hot end components,especially the turbine rotor material.Although FB2 steel is widely used in the manufacture of 620? steam turbine rotors for power plants,it cannot meet the high temperature performance requirements of power plants with temperature parameters of 630? and above.For 630 ? 650 ? unit,Japan and Europe have developed a variety of steel grades,such as: TOS110,HR1200,MARBN,FB2-3Ta,but the above steel grades lack practical application experience,and from the long-term Looking at the performance data,there are still questions about whether it can be used in 630 ? power plants.Based on the FB2 heat-resistant steel,this paper design components with reference to the strengthening ideas of TOS110,MARBN,HR1200 and other alloys,design different experimental steels with N content,Ni content,W,Mo content,combining chamber,high temperature mechanical properties and microstructure analysis,To study the strengthening and toughening mechanism of different alloy elements,to explore the enhancement effect of strengthening elements on high temperature performance,to preliminarily screen the composition range of N,Ni,W and Mo elements,to make the material selection for the steel of turbine rotor of 630? ultra-supercritical unit Pre-research and preparation work.The results of the research on the N content show that with the increase of the N content,promoting the precipitation of the MX phase improves the precipitation strengthening effect,the strength of the experimental steel increases,and the toughness decreases.The increase of N content makes the tendency of large particles of BN inclusions in the experimental steel increase,and the strengthening effect of N in the steel decreases significantly.The W and Mo equivalents have a greater influence on the mechanical properties of 9% Cr steel.The Mo equivalent increases and the strength increases,but the precipitation tendency of ?-Fe increases,and the toughness loss is serious.Mo equivalent 1.5 has good strength and toughness matching.Under the same Mo equivalent,the solid solution strengthening effect of W generation Mo is more obvious,and the experimental steel with W content of 3% can get a good plastic toughness match through the adjustment of heat treatment.The addition of Ni has no obvious effect on the room temperature strength of the experimental steel,and can improve the impact toughness of the experimental steel.When the Ni content in the experimental steel increases from 0 to 0.15%,it has no significant effect on the residual austenite content.A small amount of Ni element can ensure the impact toughness of the experimental steel.Through the analysis of the experimental and thermodynamic calculation results,it is recommended to select the N content of 0.015%,Mo equivalent of 1.5,and W,Mo compound addition and no addition or small addition of Ni element in the 630 ? rotor heat-resistant steel for subsequent experiments.Through the analysis of experiment and thermodynamic calculation results,it is suggested that the N content in steel should be selected from 0.015% to 0.020%.The combination of W and Mo should select Mo equivalent of 1.5 and replace W with Mo has good comprehensive mechanical properties,The amount of Ni added should be less than 0.15%. |
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