On the Recoveries of the Notch Toughness of Structural High Tensile Steel by Tesile Prestrain at Room Temperature

Behaviors of Over-Strained Metals (Report 6)

Abstract

The recoveries of the notch toughness of structural high tensile steel by tensile prestrain at room temperature were investigated through the standard V-notch Charpy test. The results obtained are as follows:
1. It has been generally conceived that impact value, lateral contraction and shear percentage decrease with increasing prestrain, but the recoveries of toughness at the low temperatuae range in the transition curve are recognized at about slight necking-point which is before maximum load (the 1st recovery) and at about maximum load-point (the 2nd recovery).
2. The recovery of lateral contraction is small and, on the other hand, that of impact value or shear percentage is to or above the toughness of virgin steel.
3. Ductility transition temperature rises with increasing prestrain, but it drops to that of virgin steel at the 1st and the 2nd recovery-points.
4. Fracture transition temperature is not almost affected by prestain, but it drops below that of virgin steel at the 1st and the 2nd recovery-points.
5. The recovery-points mentioned above are not changed extensively by testing temperature, within this experimental range.