The invention discloses a preparation method for a large-size hard
alloy. The preparation method includes the following steps that S1,
raw material preprocessing is conducted so that surface sundries and
oxide can be removed; S2, fluxing agent
impurity removal is conducted so that impurities in internal melt can be extracted out; S3, pouring is conducted, the melt is placed in a water-cooled
copper mold, and after pouring is completed, the water-cooled
copper mold enters a water tank to be suddenly cooled, and a blank is obtained; S4, the blank is taken, ground and formed, the blank is taken out and ground, a rough blank is obtained, and the rough blank is pressed; and S5,
sintering is conducted, wherein secondary
vacuum sintering is conducted on the rough blank,
temperature and pressure are regulated in the secondary
vacuum sintering process, a large-size hard
alloy finished product is obtained, raw materials are purified, other nodules are prevented from appearing in the forming process,
grinding is conducted after the blank is obtained, secondary
sintering and die pressing are conducted after
grinding is conducted, holes are further removed, and on the premise that the
large size is ensured, the predicted rigid degree of the hard
alloy is reached, the production period is shortened, the die occupation time is shortened, and the production efficiency is improved.