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华能玉环电厂1 号机组是国内首台超超临界机组, 首次在主蒸汽管道采用SA335P92、SA335P122材质。在1 号机组P92、P122 钢的现场焊接施工中, 采用了GTAW+SMAW工艺, 内充氩保护, 焊前预热, 进行2层氩弧焊打底, 2 层氩弧焊厚度为5~6mm, 预热方法采用电加热方式, 采用较小的焊接热输入量进行施焊。焊接结束后, 立即降温进行马氏体转变。玉环电厂1 号机主蒸汽( P122、P92) 及再热热段( P91) 经过焊缝硬度及微观金相检验符合业主的要求。 相似文献
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AbstractFinite element (FE) simulations of the welding of two high grade steel pipes are described. The first is a P91 steel pipe welded with a similar P91 weld consumable, and the second is a P92 steel pipe welded with dissimilar nickel–chromium based weld consumables. Both welds are multipass circumferential butt welds, having 73 weld beads in the P91 pipe and 36 beads in the P92 pipe. Since the pipes and welds are symmetric around their axes, the FE simulations are axisymmetric, allowing high FE mesh refinement and residual stress prediction accuracy. The FE simulations of the welding of the P91 and P92 pipes comprise thermal and sequentially coupled structural analyses. The thermal analyses model the heat evolution produced by the welding arc, determining the temperature history throughout the FE models. Structural analyses use the computed temperature history as input data to predict the residual stress fields throughout the models. Post-weld heat treatment (PWHT) of both pipes has also been numerically simulated by assuming that the FE models obey the Norton creep law during the hold time period at 760°C. The residual stresses presented here have all been validated by corresponding experimental measurements. Before PWHT, it has been found that, at certain locations in the weld region and heat affected zone (HAZ) in the pipes, tensile hoop and axial residual stresses approach the tensile strength of the material, presenting a high risk of failure. It has also been found that PWHT substantially reduces the magnitude of residual stresses by varying degrees depending on the material. 相似文献
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Nitin Saini Chandan Pandey Manas Mohan Mahapatra 《International Journal of Hydrogen Energy》2017,42(27):17328-17338
In the present investigation, varying electrode conditions (dried and contaminated) have been employed during welding of P92 steel to study the effect of diffusible hydrogen level on hydrogen-assisted cracking (HAC). Shielded metal arc welding process was employed to deposit the metal on a P92 steel plate. To evaluate HAC, the Granjon implant test with varying diffusible hydrogen content in the deposited metal was utilized. The diffusible hydrogen level was measured in the deposited metal by using the mercury method. Lower critical stress (LCS), embrittlement index (EI) and normalized critical stress ratio were evaluated from the Granjon implant test. The fracture surface morphology of fractured implant specimens has been studied by using a field emission secondary electron microscope. The P92 steel plate welded by the contaminated electrode with a high level of diffusible hydrogen was found to be more susceptible to HAC. As diffusible hydrogen content increased in the deposited metal, the LCS value and EI were observed to be decreased. 相似文献
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T. M. Hoey W. Sun D. G. McCartney J. Mansfield J. Foster 《Energy Materials: Materials Science and Engineering for Energy Systems》2018,13(2):500-509
The main limiting factor for P92 steel, in power plant at high temperature, is the increased oxidation damage on the inside surface which causes enhanced damage of components. Industry have attempted to address this problem by applying oxidation resistant coatings to the inside surface of the P92 pipework to prevent damage. Aluminide diffusion coatings have been a particular focus for research to date, however they have been found to have a number of detrimental effects on the creep properties and coating-substrate integrity. This paper introduces a Co-Cr-C type coating, composed of Cr3C2 particles electro-deposited within a cobalt matrix. On exposure to high temperature oxidation conditions the coating is shown to form a cobalt and chromium rich oxide which is slow growing, adherent and ideal for oxidation resistance. When applied to P92 substrate and exposed at service relevant temperatures the coated system retains its integrity and appears suitable for long term service. The coated P92 system is also shown to retain its integrity during high temperature creep testing and coating application does not have a negative effect on the mechanical properties of P92. Overall the Co-Cr-C coating has a number of superior properties compared to previously investigated coatings. 相似文献
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以M-92分子筛为催化剂生产异丙苯的研究 总被引:1,自引:0,他引:1
利用M-92分子筛为催化剂以丙烯和苯为原料进行液相烷基化技术生产异丙苯,烷基化最佳条件:反应温度为125~145℃;反应压力2.4~2.6MPa;n(苯)∶n(丙烯)=(2~4)∶1;丙烯空速为0.5~1.0h-1。该技术与传统AlCl3相比具有工艺简单、丙烯基本可完全转化、异丙苯选择性高、原材料消耗低、节能、及环境友好等优点,具有一定经济效益。 相似文献