Abstract
Three kinds of fiducial microgrids with ion etched groove, deposited gold and deposited platinum lines were made on creep specimens by electron lithography using a usual scanning electron microscope, and assessed for high temperature use, particularly for the measurements of micro deformation during creep. The assessment showed that the microgrid with ion etched groove lines is most stable at high temperatures and suitable for the measurement of local micro deformation such as the grain boundary sliding. Using the microgrid with ion etched groove lines, the grain boundary sliding during creep in a 321 stainless steel was measured, and an effect of grain boundary triple point on the sliding and the morphologies of grain boundary cracks at surface were studied quantitatively and geometrically, respectively. It was suggested that the formation of a micro crack at the triple point allows the sliding easily, while a flawless triple point arrests the sliding evidently. Also it was confirmed that geometrical factors such as the morphologies and size of the surface cracks are controlled mainly by the direction and amount of the sliding.
