Critical Assessment 21: oxygen-assisted fatigue crack propagation in turbine disc superalloys

Figures & data

1 Fatigue crack propagation rates in four advanced turbine disc superalloys,^5,9,21,22 where the figure legend indicates: alloy-environment-test temperature (in °C) – loading waveform (where 1:x:1:1 indicates a trapezoidal waveform: 1 second ramp up, x s at maximum load, 1 s ramp down and 1 second at minimum load).

2 Fractography of supersolvus heat treated LSHR alloy tested in vacuum and air at 650 and 725°C using 1-1-1-1 and 1-20-1-1 loading waveform.²²

Table 1  Grain size and γ΄ size in the disc superalloys presented in Fig. 1^5,9,21,22

	Grain size (µm)	Primary γ΄ (µm)	Secondary γ΄ (nm)	Tertiary γ΄ (nm)
N18	8.7 ± 4.7	2.19 ± 0.98	188 ± 112	25
U720Li	6.4 ± 1.8	1.99 ± 0.9	102	16
RR1000	7.4 ± 2.8	1.75 ± 0.9	140	18
LSHR	36.1 ± 18.1	N/A	153 ± 29	15

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