Abstract: A heat treatment and hot working method for producing a thin sheet of nickel base superalloy single crystals is described, wherein a single crystal preform of an alloy is first heat treated in vacuum at temperatures below the .gamma.' solvus temperature of the alloy in order to obtain an overaged .gamma.' microstructure in the preform, sized and surface ground in order to remove surface defects, and then preferably surrounded by plates and interlayers of refractory metal or alloy and parting agent coatings; the plates are then welded to form an enclosure and evacuated, preheated and soaked at 1093.degree. to 1150.degree. C. and rolled at roll speeds of about 0.12 to 0.25 rods in successive passes, at about 5 to 15% reduction per pass with reheating at the soaking temperature between successive passes, to a reduction in thickness of 50 to 75%; the plates are then removed and the preform is conditioned, repacked and successively rolled to preselected thickness.