THERMAL HARDENING OF HARD ALLOYS AND IMPLEMENTATION IN TOOLS

摘要

A method for thermally processing a sintered hard alloy to produce a hardened article which comprises heating a sintered hard alloy to a temperature of between about 700 and 850 DEG C at a first rate which avoids thermal shock; further heating the hard alloy to a maximum temperature of between about 1050 and 1350 DEG C at a second rate which is faster than the first rate; reducing the temperature of the hard alloy to between about 850 to 950 DEG C as soon as possible after the maximum temperature is achieved in order to substantially avoid the growth of carbide grains, said reducing being conducted at a third rate; and cooling the heard alloy to ambient temperature at a fourth rate that is slower than the third rate to obtain a hardened article. A further method of making an integral cast body containing a sintered hard alloy article which comprises sintering a hard alloy to form an article; brazing the article to an extension; placing said article and extension into a mold; and casting a body of a castable metal about said article and extension under conditions that provide thermal processing according to the method outlined above to form an integrally cast body about a portion of a hardened hard alloy article.