Article

Steel Casting

Steel casting is a special form of casting involving various types of steel. Steel casting is used when cast irons cannot deliver enough strength or shock resistance. Examples of items that are steel casting includes: hydroelectric turbine wheels, forging presses, gears, railroad car frames, bodies for valves and pumps, machinery used in mining, marine equipment, and engine casings. Steel casting are categorized into two general groups: carbon steel and alloy steel.

The methods of steel casting: The Szekely method consist of employing metal molds, one of the chief points being to coat the molds with chalk and paraffin. Shaw also employs metal molds. Slavianoff's electric steel casting method appears to be simply a method of melting steel by connecting it to one terminal of a strong electric circuit, the crucible in which it is to be melted, or the plate on which it is to be cast being attached to the other.

The solid metal must be heat up to a sufficiently high temperature, and there are two steel casting methods which are usually distinguished as (a) casting on, where the solid metal is heated with a flame, and (b) burning on, where the molten metal is first caused to run into and out of the mold until the solid portion has been sufficiently heated, when the outlet hole is closed, and the mold allowed to fill up.

STEEL CASTING WILL TEND TO HAVE THE ADVANTAGE OVER EQUIVALENT STEEL FORGINGS WHEN ANY OF THE FOLLOWING INSTANCES OCCUR:

► An unusual chemistry is required (i.e., a chemistry other than that which
 is the norm for steel mills)
 ► The parts being considered is relatively large or has complex geometry.
 ► Stresses to be applied to the part are multi-axial.
 ► Materials call-out is for high manganese (approximately 13%),
 work-harden able steel.
 ► Minimal set-up and tooling costs are a factor.

Steel casting is ISOTROPIC - meaning similar properties in all directions”. Steel forging is ANISOTROPIC - meaning “similar properties in the direction of flow’’. Thus, in the direction of flow, a steel forging’s strength is high along its longitudinal axis, and decreases in the transverse direction. Whereas, in steel casting, the properties are similar in all directions.

Steel casting is almost always lighter their forged counterparts “redesign from forgings to castings usually results in substantial savings in weight”. For example - a forged cannon muzzle brake weight 600 lbs; this same part as a casting weight 400 lbs.