Abstract
A study was made to determine the adequate amount of nickel, chromium and molybdenum enough to obtain the desired hardness in as-cast state in accordance with the wall thickness of the product.
Experimental variables were as follows:
Nickel percent: 0, 1·0, 2·0
Chromium percent: 0·5, 1·0
Molybdenum percent: 0·5, 1·0
Sample size: 30, 45, 60 mm in diam.
Molds: green, dry
To simplify the experiment a “latin-square” design was applied and the results obtained were as follows.
(1) Bainitic structure was obtained when 2% nickel, 1% chromium and 1% molybdenum had been added.
(2) The mixed structure of eutectic cementite and bainite was obtained in the low-silicon range (1·5% Si) when each content of nickel, chromium and molybdenum was 1%, respectively.
(3) From the conclusions mentioned above, the following experimental formula to determine nickel, chromium and molybdenum amount required for 300-600 Brinell hardness number was developed:
Dry mold……HB=114·4X-68·2XY+178·7 (Y+Z) +9·9
Green mold……HB=35·2X+195·OY+58·2XY+195·3Z-10·0,
where X=nickel %,
Y=chromium %, and
Z=molybdenum %.
