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Creep-Resistant Steels. Z-phase, inaccurate data.

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Presentation on theme: "Creep-Resistant Steels. Z-phase, inaccurate data."— Presentation transcript:

1 Creep-Resistant Steels

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3 Z-phase, inaccurate data

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6 Thermodynamics Cannot win, can only break even Cannot reach absolute zero Can only break even at absolute zero

7 Goal Increase as far as is possible, the maximum temperature in the cycle i.e. better materials & engineering

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10 Taylor & Thornton, ALSTOM Power, Rugby

11 0.5 µm

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15 time = t time = t+∆t  

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17 2.25Cr1Mo 600°C

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19 Yamasaki & Bhadeshia, 2003

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24 x

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27 diffusion flux distance concentration c  r c r 1 2 r 1 r 2    Coarsening

28 10 9 8 7 6 5 4 3 2 -9 10 -8 10 -7 10 -6 Time / s Mean radius / m 1/3 1/2 10 9 8 7 6 5 4 3 2 0 2 4 Number density 10 m 18 -3 Fujita & Bhadeshia, 2000 Time / s

29 10 4 3 2 1 -2 10 10 0 1 Time at 600 °C / h M_23C_6 size / µm 0W 1W 2W 4W Data from Abe, 1999 Fe-9Cr-W alloys

30 543210 0.00 0.01 0.02 0.03 Tungsten / wt% Mole fraction of phase Laves phase M_23 C_6

31 Multicomponent coarsening Venugopalan & Kirkaldy, 1978

32 543210 1.5e-19 1.6e-19 1.7e-19 1.8e-19 Tungsten / wt% Effective diffusivity / m s multicomponent chromium alone 2 Coarsening accelerated by tungsten

33 distance concentration in ferrite Laves   Multiphase coarsening ?

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35 Cole & Bhadeshia, 2002 650 o C


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