Reverse-bend and push-pull tests at 550 C on small specimens of ½ Cr-Mo-V cast blocks have been used to obtain data relevant to crack formation in steam turbine components. A dwell period at peak tensile strain reduced the endurance, but increases in the length of the dwell did not reduce the endurance proportionately because the peak stress relaxed rapidly.

Neither forging, aging, nor differences in the normalizing cooling rates significantly affected the endurance of the ½Cr-Mo-V steels tested, but oil quenching to produce fully bainitic structures altered the slope of the strain/endurance relationship. The data obtained from tests in air appeared to give conservative life predictions for components in service in steam.