Techniques for investigating the yield surface behaviour of pressure-vessel materials

Abstract

The Mises shear strain energy model has long been accepted as satisfactory for defining initial yield in the general three-dimensional stress state. For materials which strain-harden after initial yield, the situation is complex and subsequent yield surfaces will depend on the direction and level of pre-stress. This paper describes experimental techniques for investigating general yield surface behaviour, and presents illustrative results for a 2 1/4 per cent Cr, 1 per cent Mo pressure-vessel steel.