Non-heat treatable grades of steel are those which cannot have their mechanical properties modified due to heat treating. They achieve their mechanical properties through a combination of chemistry selection and forging method.
Forging reduction should be sufficient to consolidate the defects inherent to the casting process such as porosity and other voids while achieving a general wrought structure by breaking down the cast structure. A 3-to-1 reduction, using the open die process, is usually sufficient to achieve these results (with strict control of the process, less than 3-to-1 can be sufficient). Depending on the alloy and customer requirements, higher reduction may be necessary to achieve certain additional mechanical or physical requirements.
A forging is metal that has been heated in order to soften it then pressed, hammered, or otherwise formed into a shape. All forgings begin as cast starting stock. Forgings benefit from the forming operation which enhances their overall toughness and fatigue resistance.
