Forging Terms and Definitions: F-I

From Flow lines to Isothermal forging
Courtesy of Forging Industry Association

Flow lines: patterns that reveal how the grain structure follows the direction of working in a forging.

Forgeability: relative ability of a material to deform without rupture.

Forging reduction: ratio of the cross-sectional area before and after forging; sometimes refers to percentage reduction in thickness.

Forging stock: wrought rod, bar, etc. used as the raw material or stock in forging.

Free-machining-steel forgings: those made from steels with special alloying-element additions to facilitate machining.

Grain flow: fiberlike lines that show (via macroscopic etching) the orientation of the microstructural grain pattern of forgings achieved by working during forging processes. Optimizing grain flow orientation maximizes mechanical properties.

Hammer forging: one produced on a forging hammer, usually between impression dies but sometimes flat dies; the process of forging in a drop hammer (see drop forging).

Hand forging: one made by manually controlled manipulation in a press without impression dies, usually between flat dies with progressive forging of the workpiece; also referred to as flat-die forging.

Heat treatment: heating or cooling operations, sometimes isothermal, to produce desired properties in forgings.

High-energy-rate forging: forgings made on equipment that utilizes very high ram velocities.

Hog-out: product machined from bar, plate, slab, etc.

Hollow forging: a cylindrical open die forging, e.g., thick-walled tubes or rings.

Hot-die forging: a process in which dies are heated close to the forging temperature of the alloy being forged/ used for difficult-to-forge alloys.

Hot forging: same as hot working - plastically deforming an alloy at a temperature above its recrystallization point, i.e., high enough to avoid strain hardening.

Hub: a boss in the center of a forging that forms an integral part of the body.

Iconel Alloy:  a trademark of Special Metals Corporation that is a nickel-chromium-based superalloys.

Impact extrusion: a reverse extrusion process in which metal is displaced backwards between a punch and a die to form a hollow part.

Impression die forging: one formed to shape and size in die cavities or impressions; also commonly referred to as closed die forging.

Isothermal forging: is most commonly conducted at about 2000 degrees F under a controlled atmosphere or vacuum to prevent oxidation while forging superalloys.

For more information about common forging terminology, visit the Forging Industry Association (FIA) website.

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