© 2013 Siemens Energy, Inc. All rights reserved. 3.2. Effect of temperature on FCG rates Figure 5 compares the growth rate of cracks traveling in longitudinal direction at both temperatures. In longitudinal direction, cracks seem to grow equally fast at both temperatures, and no obvious differences can be found between T0 and T0+250 0C. Figure 5. Crack growth behaviors of TL type specimens at T0 and T0+250 0C In Figure 6, weak temperature dependence can be found on the LT type crack growth rate, i.e., cracks grow slightly faster at T0+250 0C than at T0. Figure 6. Crack growth behaviors of LT type specimens at T0 and T0+250 0C Figure 7 compares the growth behaviors for diagonal cracks traveling both at T0 and T0+250 0C, from which one can conclude that apparent temperature effect can be found on the diagonal crack growth. Generally, cracks propagate much faster at T0+250 0C than at T0, especially in the low- KΔ regime. Subsequently, the growth rate at both temperatures become more and more close to each other as KΔ arise, and they take nearly the same value when normalized 2.5 KΔ ≈ . After that, cracks at T0 start to exceed those at T0+250 0C, until the final break.
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