Abstract
In the steel casting foundry, properties of the steel which satisfy tbe casting are hitherto been neglected, but for manufacturing the good steel castings the properties of the steel are very important. And melting practice whicl satisfies these properties is necessary. Properties which are demanded for the steel castings are as follows:
1. Free from blow holes, pin holes.
2. Safety for the hot tear.
3. Good fluidity.
4. Mechanical property.
5. Good. weldability.
These properties are satisfied by the melting practice under the conditions.
1. Elimination of H2, O2-
2. Control of the composition.
3. Control of the temperature of the molten steel.
So that, the melting of the steel castines by the basic electric furnace should be differ from that of the ingot making. And following should be demanded.
1. An object of the oxidizing period is to eliminate H2.
2. Moderate decurburizing speed should be necessary and other composition should not be decreased as possible.
3. Deosidizing should be forced as possible in the deoxidizing period.
4. Consequelltly. non metallic inclusions are allowed unavoidably.
5. S should be decreased as small as possible to avoid the hot tear.
6. Mn should be added much more than the quantity which needed for the deoxidation to prevent the hot tear.
7. Elimination of the gases in the molten steel is the most important which decide the fini-shing condition of the steel.
8. Tapping temperature should be higher than 1520°C.
