抄録
The present paper describes experimental results on contribution of the padding and the characteristic mode of freezing to form the sound area in the casting of several metals, such as commercially pure aluminum, high strength yellow brass, tin bronze and steel. The bar and plate castings which were of 220mm length and variously tapered linearly from end to riser were tested, and from those results discussions were given on the critical padding about each alloy and casting shape.
Considerable increase in sound area was obtained with relatively small padding in the skin formation type alloys, such as pure aluminum and high strength yellow brass. On the other hand, the increase of sound ares could not be expected in the castings of mushy type alloy such as tin bronze.
In the case of tin bronze, it is rather desirable to avoid padding because the mechanical properties were made worse with the increase in thickness of castings.
Estimating the effect of degree of padding in each casting shape, less degree of padding was sufficient to obtain enlarged sound area in plate than in bar. Linear relationship was found between the critical padding and the critical temperature gradient, therefore the former may be decided by obtaining the latter experimentally.
