Small punch testing in creep conditions

The creep behavior of low-alloy steel was studied using small punch tests u nder the action of constant force. Disks with a diameter of 8 mm and a thic kness of 0.5 mm were pushed against a die with a bore of 4 mm diameter usin g a ball of 2.5 mm diameter. The time dependence of the central deflection was registered. The resulting dependence has the sigmoidal shape typical of conventional creep tests but with a very significant primary stage. The co nventional constant-stress creep tests were performed fbr comparison. A sim ple method for the approximate correlation of the force in small punch test s with the stress in conventional creep tests of the same duration is sugge sted.