Low thermal-expansion gray cast iron strengthened by crystallizing dispersed carbide particles

摘要

Low thermal-expansion gray cast iron with high strength and hardness was produced by dispersing carbide particles by means of alloying carbide-stabilizing elements such as Nb, Cr, W, V, Ti and Mo up to 5 at.%. Increasing the alloying content of each element results in increasing the area fraction of carbide and decreasing in that of the graphite fraction, and it results in remarkable increasing in hardness. Tensile strength increases remarkably with increasing in alloying content of Cr or V, but it becomes maximum at some 1 at.% in the case of W or Nb. The increasing in tensile strength and hardness was discussed from such viewpoints as increasing in area fraction of carbide and increasing in effective sectional area ratio resulted from decreasing in area fraction of graphite. The coefficient of mean linear thermal-expansion at 373K increases largely with increasing alloying contents in the case of Cr, W or Mo, but it increases only slightly in the case of Ti,V or Nb.