Strain-controlled, and load-controlled fatigue tests for a 12Cr-2W ferritic heat-resistant steel were carried out at high temperatures in order to obtain the fatigue life in a wide range from 10
2 to 10
9 with loading alignment-adjusted testing machine. There was scarcely the scatter in a wide range from 10
2 to 10
7 cycles by strain-controlled tests and from 10
3 to 10
9 cycles by load-controlled tests. As for strain-controlled data, the Manson-Coffin relationship (Δε
p vs. N
f, where Δε
p is plastic strain range and is number of cycles to failure) was not linear but curved near 10
4 or 10&
5 cycles at 600, 650 and 700°C. Fish-eye fracture was observed at 400°C over 10
4 cycles, and at 650°C over 10
6 cycles. The fish-eye fracture seemed to reduce the fatigue strength in high-cycle region.
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