This paper shows how fatigue tests at elevated temperature solve many problems pertaining to aeronautical materials. Prolonged periods (5000 or 10 000 h) at 150 C (302 F) did not diminish the fatigue limit at 150 C (302 F) of the aluminum alloy 2618-T6. Consequently, the aerodynamic heating of airframes at Mach 2 does not reduce the fatigue limit of this alloy.

The “bright shot” or shot-peened surface conditions do not increase the hot-fatigue limit of a heat-resistant alloy. The Office National Etudes et Recherches Aérospatiales (ONERA) process for the chromaluminization of the heat-resistant alloy Inconel 713 does not modify the fatigue limit at 700 C (1290 F). Similarly, gases resulting from kerosine (0.5 percent sulfur) combustion do not reduce the hot-fatigue resistance of four heat resistant alloys. The fatigue characteristics of various superalloys— unidirectional or composites made by the ONERA process—at 800 C (1470 F)—are equal to or even superior to those classic heat-resistant alloys, cast or forged. A cermet of 50 percent of chromium and 50 percent of alumina retains, even at 1200 C (2190 F), a resistance to fluctuating flexure stresses of 69 ± 49 MN/m² (10 ± 7 ksi).