Effect of metallurgical factors on the low-endurance fatigue of steel in some ambient media

Abstract

1. Vacuum-refining, which brings about a reduction in the quantity of non-metallic inclusions, harmful impurities, gases and other metallurgical defects, increases the fatigue resistance of steel (in the low endurance range) in air and in corrosive and hydrogen-charging media. The largest difference in endurance between open-hearth and vacuum-refined steel is observed for-specimens fatigued in a hydrogen-charging medium. 2. Specimens cut in the direction of rolling have a higher endurance than transverse specimens. Increasing the fatigue test strain amplitude causes a substantial increase in this difference for specimens tested in air and, to a lesser extent, in a corrosive medium, and markedly reduces it in tests in a hydrogen-charging medium. 3. Increasing the degree of reduction of steel in hot-rolling causes a slight increase in its endurance in air, but has little effect on this property in a corrosive medium. When the fatigue tests are carried out in a hydrogen-charging medium, increasing the degree of hot-working causes a reduction in the endurance of steel to an extent which increases with increasing fatigue strain amplitude.