AbstractThe effect of temperature on fatigue-crack propagation in air for 1·8 Ni–Cr–Mo–V steels over the range 24–400°C has been investigated. The variables examined were: (i) specimen orientation (Y–X and X–Y); (ii) steel preparation route (vacuum or air melted); and (iii) vanadium content. In general increasing the test temperature resulted in increased fatigue-crack growth rates, the same trend being observed for both Y–X and X–Y oriented specimens. The air-melted steel exhibited higher crack growth rates than the vacuum-melted steels. Fractographic studies showed that the crack-propagation mechanism was temperature dependent in the steels studied, but differed for vanadium-bearing and vanadium-free steels.MST/48