The forging process, one of the oldest methods of metalworking, is often still the best suited for many part applications. Due to upgraded computer controlled production equipment, new raw material grades, and tooling advancements, the forging industry has grown to meet modern needs.
There are several forging processes available, including impression or closed-die, cold forming, open-die, and seamless rolled rings. This column will detail specifically the benefits of open-die and seamless rolled ring forgings.
Forging is the process of forming and shaping metals through the use of localized compressive forces. Open-die and seamless rolled ring forgings are worked above their recrystallization temperature and are gradually shaped into the desired configuration through the skillful hammering, pressing, or rolling of the workpiece.
Since both ferrous and nonferrous metals can be forged and raw material mills allow for the development of custom-melt materials, the options for grades as well as physical and mechanical properties are endless. To give an idea of options available, the following list shows the wide spectrum of materials options that can be forged:
•Carbon and alloy steel
While the material options are impressive, the unique advantages of open-die and rolled ring forging methods is really what sets this type of metalworking process apart from others. The open-die and rolled ring forging process takes the unique advantage of elevated-temperature plasticity of metals to deliver significant economic, manufacturing, and part quality advantages when compared to alternative metalworking processes. The biggest three integrity advantages of the open-die and rolled ring forging methods are directional strength, structural strength, and fracture resistance.
By mechanically deforming the metal above their recrystallization temperature and under specifically controlled conditions, the forging process produces predictable and desirable grain flow characteristics and grain refinement, which results in improved mechanical properties and metallurgical soundness. These qualities translate into superior metallurgical and mechanical capabilities by delivering increased directional strength in the final part as required.
Forging provides structural integrity that is unmatched by other metalworking processes. By consolidating the ingot center, forging eliminates internal voids and porosity. The process also breaks up and eliminates the dendritic structure that is inherent in the original cast ingot. Predictable structural integrity reduces the need for part inspection requirements, simplifies heat treating and machining, and ensures optimum part performance under field service conditions.
Parts can also be forged to meet many challenging fracture test requirements. Fracture testing includes the common Charpy impact test and also fracture toughness, drop-weight, and dynamic tear tests. Targeted orientation of grain flow assures maximum fracture and fatigue resistance in critical locations. The high-strength properties of the forging process can be used to reduce sectional thickness and overall weight without compromising final part integrity.
*References used: Forging Industry Association trade publications.