Measurement of low resistances by means of the wheatstone bridge

Abstract

Dissimilar joints between ferritic and ausenitic materials are complex in terms of the heterogeneity of the weldment structures and their physical, mechanical and time dependent properties. Recent work studied the effect of slow thermal cycles, incorporating pressure increases and hold periods at the peak temperature, on the strain accumulated in dissimilar welds between 2.25CrIMo low alloy steel and Type 316 stainless steel fabricated with Inconel and Type 316 filler metals. The current paper examines the effect of thermal cycles and the time at peak temperature and stress on the elastic strains developed during pressure loading of the joints. The results suggest that creep damage caused during the hold period at high temperature can influence the loading-unloading strains, which generally increases with increasing damage. It is suggested that such methods could have potential for monitoring of creep damage in dissimilar welds in service and laboratory test situations.