Nearly any metal, or combination of metals can be forged. Choosing the right alloy combination is important to meeting your part requirements. Some things to consider when determining what your part should be made of includes:
- Strength – The mechanical property requirements for Yield Strength (Yield), Ultimate Tensile Strength (UTS), Elongation and Reduction of Area ROA) must be calculated A safety factor multiple over model predictions is often be needed to account for shock/momentary loading. The wrought properties provided by forging consistently provide ultimate strength for almost every alloy.
- Durability – Impact toughness is another means to provide guidance for shock/momentary loading, especially in-service conditions where such loads may be frequent or continuous. The thermomechanical process of forging drives recrystallization of fine-grained microstructure, metallurgy that provides the highest resistance to fatigue failure and the superior impact toughness of alloys.
- Corrosion Resistance – For alloys designed for corrosive environments, forgings provide best results, achieving 100% density of fine-grained microstructure, providing fewer pathways for chemical attack than competing metal working processes.
- Heat Resistance – Tough to forge, but providing even tougher end products, alloys containing refractory metals, subject to thermomechanical deformation, achieve metallurgy that survives longer and stronger than other means of production, uniformly sloughing sacrificial surface. Components constructed using other methods can form preferential fissures and weak spots leading to premature and unplanned failures.
- Conductivity – Alloys designed for thermal, magnetic, or electrical conductivity, such as copper, aluminum, and silicon/core iron, can gain improved conductivity or magnetic permeability from the thermomechanical processing of forging, due to assurance of full density and specific microstructure. Engineering the forging design to achieve optimum metallurgy assures these materials perform efficiently and effectively.
- Formability – Metals and metal alloys cover a wide range of formability, from “softer” metals, such as copper or aluminum, that require less force at relatively lower temperatures, to “super alloys” and refractory metals that must be forged at high temperatures with equipment capable of delivering high forces to deform the alloy. Choosing an alloy that will perform function while being highly formable will provide the maximum cost benefit.
- Machinability – With consistent metallurgical structure throughout the entire cross section, forgings provide repeatable machining outcomes. Unlike other metal working processes, voids, inclusions, alloy segregation or hard spots that interrupt machining operations and break tools are not found in forged product.
- Ductility – Often overlooked as attempts are made to increase yield strength of lesser alloys from other metal working processes, wrought product achieves high yield strength while maintaining ductility. Forged product is famous for withstanding extreme overload, tough but yielding, avoiding the catastrophic failure of sudden fracture.
- Tensile Strength – Wrought properties provide the ultimate strength achieved by any common alloy.
- Forging Process – The thermomechanical process in which material is deformed in a solid state to achieve bulk shape and metallurgical requirements of a component part. When components are intended for severe service, maximum safety or greatest durability, forging is the process of choice.
- Secondary Processes – Along with the benefits in machining versus other processes, forgings also provide superior results in heat treating, plating, and coating. Consistent metallurgy through an entire production run assures heat treat results without variations. Plating and anodizing forged surfaces, both “as forged” and machined, face no inconsistencies due to porosity or contamination from inclusions.
- Material Cost – In design, the question is, what material will meet the service and safety requirements with cost efficiency? The wrought properties from forging allows design using available alloys and the ability to depend upon the established standards through the entire cross section of the component. Providing consistent, assured properties, forging allows use of the most cost-effective alloys with highest reliability.
- Availability – Alloys suitable for forging are available from the warehouse and many more can be ordered in volume from mill supply. It is always best to check on what alloys are readily available before making a final design selection.
- Quantity Required – Small volumes mean warehouse availability will be necessary for try-out, first article, or initial production lots. Better pricing, available from mill purchase, can follow if volumes become sufficiently large.
- Waste – Every process produces scrap or waste material. Virtually every forging alloy can be recycled for every stage, from initial saw cut swarf and bar ends to end-of-life cycle of the finished product.