Effects of test specimen geometry on creep behaviour of 12Cr steel in miniaturised disc bend tests

Abstract

The results of miniaturised disc bend creep tests carried out on flat and on preformed sombrero shaped disc test specimens made of high alloy 12Cr steel have shown that the time to rupture is practically the same for both kinds of test specimen. It was therefore proven that the initial, large and rapid hot plastic deformation of flat disc test specimens does not effect the regularity of the creep process in such tests. Miniaturised disc bend creep tests carried out on flat disc test specimens of slightly different thickness confirmed the general validity of the modified Mukherjee - Bird - Dorn power law relation for time to rupture with thickness of the disc as the equation parameter. However, the thickness of the disc should be smaller or at most equal to the actual die clearance of the disc bend creep testing equipment.