Reduction of Area (Contraction of Area)
The difference in a tension specimen between the size of the original sectional area and that of the area at the point of rupture. It is generally stated as an percentage of decrease of cross-sectional area of a tension specimen after rupture.
Residual Alloys
Small quantities of unspecified alloying elements found in steel but not added intentionally.
Ring Rolling
The process of shaping welding rings from pierced disks or thick-walled, ring-shaped blanks between rolls that control wall thickness, ring diameter, height, and contour.
Rockwell Hardness Test
A method of determining the relative hardness value of a material by measuring the depth of residual penetration by a steel ball or diamond point indenter under controlled loading.
Rolling
The forging operation of working a bar between contoured dies while turning it between blows to produce a varying circular cross section.
Rough Machining
A machining operation that allows stock for subsequent finish machining.
Sadden
To lightly forge an ingot in the intentional forging operation to break up and refine coarse, as-cast structures at the surface.
Sand Blasting
The process of cleaning forgings by propelling sand against them at high velocity. See also Blast Cleaning.
Scarfing
Removal of surface irregularities by use of an oxygen torch. Scarfing of forgings is usually done during the hot working phase of processing.
Scale
The heavy iron oxide layer that forms on the surface of steel at forging temperatures; also the lighter oxide layer formed at heat treating temperatures.
Scleroscope Hardness (Shore)
A hardness test in which the unit of value is a number derived from the height of rebound of a tup falling on the object from a fixed height under the acceleration of gravity.
Seam
An elongated surface defect.
Secondary Hardening
An increase in hardness occurring during temperature operations of certain alloy steels.
Segregation
Non-uniform distribution of alloying elements, impurities, or microphases.
Selective Heating
A process in which only certain portions of an object are heated.
Set-Down
The drop from a heavy sectional area to a lighter sectional area.
Shaping
The process of forming a straight surface with a machine tool in which the work is held stationary and the tool moves on a ram in a horizontal plane.
Shearing
A process of mechanically cutting metal bars to the proper stock length necessary for forging the desired product.
Shot Blasting
A process of cleaning forgings by propelling metal shot at high velocity by air pressure or centrifugal force at the surface of forgings. See also Blast Cleaning.
Shrinkage
The contraction of metal during cooling after forging. Die impressions are made oversize according to precise shrinkage scales to allow forgings to shrink to design dimensions and tolerances.
Sizing
A process employed to control precisely a diameter of rings or tubular components.
Smith
A blacksmith, forger, or pressman.
Soaking
Holding steel at a temperature to attain a uniform temperature throughout.
Solution Heat Treatment
A process in which an austenitic stainless steel is heated to a suitable temperature, held at this temperature long enough to permit a constituent to enter solid solution, and then cooled rapidly to retain that constituent in solid solution.
Spalling
The cracking and shelling of small particles from a metal surface.
Spheroidizing
A from of annealing consisting of prolonged heating of iron-base alloys at a temperature in the neighborhood of, but generally slightly below the critical range, usually followed by a relatively slow cooling. Spheroidizing causes the iron carbide to assume a spheroidal shape, hence the name.
Stainless Steel
Steels that are corrosion- and heat-resistant and contain at least 10 percent chromium. Other alloying elements are often present.
Strain
The elastic or plastic deformation of a steel resulting from stress.
Stress
A load that elastically or plastically deforms a metal.
Stress Relieving
A process for relieving residual stresses in steel forgings by heating to a suitable temperature below the tempering temperature, holding for a sufficient time, and cooling slowly and uniformly. This treatment may be applied to relieve stresses induced by quenching, normalizing, machining, cold working, or welding.
Swage
Operation of reducing or changing the cross-sectional area by revolving the stock under fast impact of blows. Finishing tool with concave working surface; useful for rounding out work after its preliminary drawing to size.
Tears
Surface ruptures in metals.
Tempering
Reheating a quench-hardened or normalized ferrous alloy to a temperature below the transformation temperature range.
Tensile Properties
The mechanical property data obtained from a tension test, such as tensile strength, yield point or yield strength, percent elongation in gauge length, and percent reduction in area.
Tensile Strength
The maximum unit stress, based on the original test cross-sectional area, in a tension test carried to rupture.
Thermal Cracks
Ruptures in metal set up by stresses due to thermal differentials.
Tolerance
The specified permissible deviation from a specified nominal dimension or the permissible variation in size of a part.
Transformation Temperature Range
The range of temperature over which ferrite and pearlite transforms to austenite on heating, and austenite transforms to ferrite and pearlite on cooling.
Trepanning
Removal of a core of metal by a hollow tool. May be performed by a hollow punch at forging temperatures or by a hollow cutting tool by machining at ambient temperatures.
Tumbling
The process for removing scale from forgings in a rotating container by means of impact with each other and abrasive particles and small bits of metal. A process for removing scale and roughness from forgings by impact with each other, together with abrasive material in a rotating container.
Turning
Removing metal from the outside of a part by means of a tool in a lathe or similar machine tool.
Ultrasonic Testing
A nondestructive test applied to sound-conductive materials having elastic properties for the purpose of locating inhomogeneities or structural discontinuities within a material by means of an ultrasonic beam.
Upend Forging
A forging in which the metals is so placed in the die that the direction of the fiber structure is at right angles to the faces of the die.
Upset
Working metal in such a manner that the cross-sectional area of a portion or all of the stock is increased, and length is decreased.
Upset Forging
A forging obtained by set of a suitable length of bar, billet, or bloom; formed by heading or gathering the material by pressure upon hot or cold metal between dies operated in a horizontal plane.
Upsetter (Forging Machine)
A machine, with horizontal action, used for making upset forgings.
