Microstructures in historical and archaeological steel objects resulting from aging process

The passing of larger periods of time produces appreciable aging effects in iron and steels. This study, which has been conducted on historical and ar chaeological iron and steel objects originating from the Iron Age up to the Medieval period, has provided information concerning characteristic micros tructures with which the aging phenomenon can be explained. All examined ob jects show signs of important changes in the original microstructures. From observing the structures it has been deduced that conventional heat-treatm ents do not give completely stable structures. The passing of greater perio ds of time seem to promote slew diffusion processes, which results in more stat,le, crystalline forms [1].