Neshicage The manufacture of Apy 22 APU requires extreme precision at every stage of the production process. In terms of fabrication, however, Crofer 22 APU is just as easy to handle as a standard stainless steel. Central Press Office for Journalists. Company Products Investors Newsroom.
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Creep properties of the given steels are evaluated by constant-load tests at oC to oC. Several creep lifetime models are applied to correlate the creep rupture time with applied stress or minimum creep rate. Comprehensive comparisons between Crofer 22 APU and Crofer 22 H steels are made on the tensile strength and creep resistance so as to characterize the influence of additions of refractory elements Nb and W.
Out-of-phase TMF tests as well as TMF-creep interaction tests under various combinations of cyclic mechanical and thermal loadings are conducted at a temperature range of 25oCoC for Crofer 22 H to study its long-term durability for applications in pSOFCs.
Experimental results show the variation of yield strength with temperature in Crofer 22 APU can be described by a sigmoidal curve for different deformation mechanisms. According to the creep stress exponent, activation energy, and microstructural observations, a diffusion-controlled dislocation creep mechanism is involved in the creep behavior of Crofer 22 APU steels at oCoC, while a power-law dislocation creep mechanism interacting with an in-situ precipitation strengthening mechanism is involved in the creep behavior of Crofer 22 H steels at oCoC.
A significant coarsening of the Laves phase is responsible for a reduced improvement of creep resistance in Crofer 22 H at the low-stress, long-term region of oC. The relation between creep rupture time and normalized stress for both steels is well fitted by a universal simple power law for all of the given testing temperatures.
Larson-Miller relationship is also applied and shows good results in correlating the creep rupture time with applied stress and temperature for both steels. Fractographic and microstructural observations indicate a ductile, dimpled fracture pattern with considerable necking is identified for the Crofer 22 APU and Crofer 22 H specimens after creep test.
Experimental results of Crofer 22 H steels under TMF loadings show the number of cycles to failure for non-hold-time TMF loading is decreased with an increase in the minimum stress applied at oC. There is very little effect of maximum stress applied at 25oC on the number of cycles to failure. The non-hold-time TMF life is dominated by a fatigue mechanism involving cyclic high-temperature softening plastic deformation.
A hold-time of h for the minimum stress applied at oC causes a significant drop of number of cycles to failure due to a synergistic action of fatigue and creep. Creep and creep-fatigue interaction mechanisms are the two primary contributors to the hold-time TMF damage. The creep damage ratio in the hold-time TMF damage is increased with a decrease in applied stress at oC and an increase in number of cycles to failure.
Crofer 22 APU is characterized by:? UNS applied for W. Mechanical properties Product 0. Fabrication and heat treament Crofer 22 APU can readily be hot and cold worked and machined. Heating Workpieces must be clean and free from all kinds of contaminants before and during any heat treatment.
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Kakinos Together with the other alloying elements titanium and manganese, the lanthan ensures that a protective coating of chromium manganese oxide forms on the surface of the interconnector plates as soon as the fuel cell becomes active. Central Press Office for Journalists. As well as making the electrical connection they also supply the cells with fuel gas and air via gas passages. During subsequent hot rolling it is important that the temperature window is observed precisely. Chromium also limits the thermal expansion of 2 alloy, giving it a similar coefficient of expansion to the surrounding ceramic xpu. The SOFC is a fuel cell variant which works at temperatures up to degrees. Home Cgofer Press releases.
Crofer 22 APU: new material for fuel cells
A methodology of evaluating the joint strength at room temperature RT and oC was developed by testing two types of sandwich-like specimens under shear and tensile loading. The effects of joining temperature, pre-oxidization of metallic interconnect, number of initial spreading side, aging treatment, and composition of metallic interconnect on the joint strength at RT and oC were studied. The measured shear strength of the specimens joined at oC was greater than that of those joined at oC. Apparently, an increase of joining temperature could improve the joining performance due to a better wetting behavior of glass ceramic.