Glossary

P.S.I.

Pounds per square inch.

Paper Interleaved

To prevent damage to the surface during shipment, handling, or storage, the material is frequently coiled with a large roll of paper paid off at the same time so that between each wrap of metal there is a wrap of paper. This paper between the steel wraps prevents the surface of the metal from rubbing against each other to spoil the surface.

Pass

In a rolling mill one pass is equivalent to one individual reduction in gauge of the entire coil being processed. A number of passes may be required to achieve the aim gauge for a particular rolling operation.

Passivation

Immersion of stainless steel in a solution of nitric acid, or of nitric acid plus oxidizing salts, which restores the original corrosion resistant surface by forming a thin transparent oxide film. The treatment also dissolves any embedded or smeared iron picked up on the surface during processing. Ulbrich does not have the capability to passivate. Because of the manner in which the product is processed at Ulbrich, passivation is not considered necessary.

Passivity

A relatively inactive state in which the metal displays a more noble behavior than thermodynamic conditions predict or more simply defined as the reason why the metal does not corrode when it should.

Pearlite

A eutectoid transformation product of ferrite and cementite that ideally has a lamellar structure but that is always degenerate to some extent.

Peening

Mechanical working of metal by hammer blows or shot impingement.

Percent Reduction

Expression of reduction in gauge during any rolling process. Percent reduction equals starting gauge minus finish gauge after rolling divided by starting gauge times 100.

Permalloy

Nickel alloys containing about 20 to 60% Fe, used for their high magnetic permeability and electrical resistivity.

Photoetch Quality

Product description for USSM flatroll coils which requires excellent finish and critical flatness.

Photomicrograph

A photographic reproduction of any object magnified more than ten diameters. The term micrograph may be used.

Physical Properties

Those properties discussed in physics (exclusive of those described as mechanical properties), for example, density, electrical conductivity, coefficient of thermal expansion. The term physical properties is often used incorrectly to describe mechanical properties.

Pickling

Removing surface oxides from metals by chemical or electrochemical reaction.

Pig Iron

(1) High-carbon iron made by reduction of iron ore in the blast furnace. (2) Cast iron in the form of pigs.

Pinholes

Microscopic imperfection of the coatings, that is, microscopic bare spots, also microscopic holes penetrating through a layer or thickness of light

Pipe

A cavity occurring in ingots, blooms, billets, bars or wire resulting from contraction of metal during solidification of ingots.

Pitting

Sharp depressions in the surface of the metal generally attributed to localized chemical attack by a corrosive media. In stainless steels, molybdenum additions (i.e. types 316, 317, 434) help improve pitting resistance.

Planimetric Method

The method of measuring grain size, in which the grains within a definite area are counted.

Planishing

Producing a smooth surface finish on metal by rapid succession of blows delivered by highly polished dies or by a hammer designed for the purpose, or by rolling in a planishing mill.

Plasticity

The ability of a metal to be deformed extensively without rupture.

Plate

Carbon steel plates comprise that group of flat-rolled finished steel products within the following size limitation

• 0.180 in or thicker, over 48 in wide;
• 0.230 in or thicker, over 6 in wide;
• 7.53lb/sq ft or heavier, over 48 in. wide;
• 9.62lb/sq ft or heavier, over 6 in. wide.

Pounds Per Inch of Width (P.I.W.)

Pounds per inch of width refers to the weight of a one-inch wide multiple of a coil. To determine the PIW, divide the weight of the coil by its width in inches.

Pouring

The transfer of molten metal from the ladle into ingot molds or other types of molds; for example, in castings.

Powder Metallurgy

The art of producing metal powders and of utilizing metal powders for the production of massive materials and shaped objects.

Precipitation Hardening

Process of hardening an alloy in which a constituent precipitates from a supersaturated solid solution.

Precipitation Heat Treatment

Any of the various aging treatments conducted at high temperature to improve mechanical properties.

Preheating

Heating before some further thermal or mechanical treatment. For tool steel, heating to an intermediate temperature immediately before austenitizing. For some nonferrous alloys, heating to a high temperature for a long time, in order to homogenize the structure before working.

Process Anneal

Heating an alloy or metal below the transformation temperature to facilitate softening. In some alloys (i.e. 410, 420, 440), heating above the transformation temperature can result in hardening with air cooling to room temperature. Therefore, process annealing must be employed at USSM to avoid the hardening which would occur at air cooling from higher temperatures.

Profilometer

An instrument that measures surface roughness the height and depth of surface ridges.

Punch

The movable part that forces the metal into the die in equipment for sheet drawing, blanking, coining, embossing and the like.

Punching

Shearing holes in sheet metal with punch and die.

PVC Coating

PVC is an abbreviation for polyvinyl chloride plastic, a material used to coat stainless steels. The heavy plastic ranges from 0.001 to 0.006 inches thick, normally has a dye in it to color it (white or black) and one side has a contact adhesive coating. Customers use it to protect the surface of the stainless while they are doing manufacturing operations on it and then peel it off after they are finished with those operations. PVC should not be allowed to remain on the stainless for extended periods of time, especially in sunlight, as it will adhere to the stainless more and more tightly as time goes on and can, in extreme cases, be virtually impossible to remove.

Pyrometer

An instrument of any of various types used for measuring temperatures.