PURPOSE: To extend the life of a die by carburizing the surface of the die consisting essentially of tungsten for die casting then subjecting the same to treatment of titanium carbide.

CONSTITUTION: The surface of a die for die casting consisting of a refractory metallic material consisting essentially of tungsten, for example, W(90%)-Mo(4%)-Fe (2%) is subjected to carburizing with a carburizer, whereby a WC layer is formed. Next, it is subjected to titanium-carbide treatment by causing gaseous TiCl4 and H2 to react at about 900°C, whereby a TiC layer is formed.