Tensile Flow Behavior of 9Cr–2WVTa Reduced-Activation Ferritic/Martensitic Steel

Tensile flow behavior of 9Cr–2WVTa ferritic/martensitic (RAFM) steel in normalized-tempered condition has been studied based on Voce equation over the temperature range of 25–600 °C. Yield strength (YS) and ultimate tensile strength (UTS) decrease with increase in temperature. However, the elongation decreases with increase in temperature up to 400 °C and then increases beyond 400 °C. True stress–true plastic strain curves at all temperatures are adequately described by the Voce equation. While saturation stress (σs) decreases with temperature, the rate at which the stress approaches the saturation value (nV) increases with temperature. The variation of the stress increment up to saturation stress (σun) with temperature shows a plateau in the temperature range of 200–400 °C. Moreover, the product of σun and nV (σun·nV) is inversely proportional to the elongation. The relation of elongation to σun·nV can be described by a power law with the exponent of −1.63.

Plane-Strain Compression of a Three Layer Strip Containing Viscoplastic Material with Saturation Stress

The plane strain compression of a long symmetric strip consisted of a three layer material between rigid, parallel, rough plates is under consideration. Two possible geometrical configurations of the layers are examined (a) a viscoplastic material is situated between two layers consisting of a rigid/perfectly plastic material, (b) a rigid/perfectly plastic material lies between two viscoplastic layers. It is assumed throughout the paper that the viscoplastic law is bounded in that sense that it reaches its critical value (saturation stress) as the strain rate tends to infinity. Exploiting closed form solutions obtained, qualitative differences between them and the known from literature solutions for three layer material structure with classic viscoplastic material are discussed. Asymptotic behaviour of solutions in the vicinity of maximum friction surfaces is analysed for any configuration.