THE WARM PRESTRESSING EFFECT IN STEELS UNDERGOING INTERGRANULAR FRACTURE

Abstract— The warm prestressing (WPS) effect has been studied in three different steels. One of these, a Cr-Ni steel (EN36), was heat treated to cause fracture to occur either intergranularly, by cleavage, or by a mixture of cleavage and intergranular fracture. A plain carbon steel (EN3) was also used for experiments involving cleavage fracture and thermally aged A533B was used for additional experiments involving intergranular fracture. A significant WPS effect was found for each fracture mode. There were slight differences in the magnitude of the effect for different groups of specimens but, except in certain special cases, these were not considered significant. Experiments involving stress relieving treatments following warm prestressing were also carried out. They indicated that the WPS effect was not completely eliminated by stress relieving. Crack blunting during warm prestressing has been proposed to account for this and for certain other aspects of the results.