Metal Glossary

Designed to be a quick reference guide for customers, the Cashmores glossary provides definitions of the latest metal industry terms.

Metal Glossary

Designed to be a quick reference guide for customers, the Cashmores glossary provides definitions of the latest metal industry terms.
  • Pick-up
    Irregular surface roughness or damage caused by adhesion and subsequent fracture or tearing between the forming tools and the work piece.
  • Pips, Pip Marks, Pip Lines
    Ident Pips
    A marking on an extrusion (on a non-visible surface) placed there by the extrusion mill’s die to allow the mill to identify extrusions produced by that mill.
  • Pitting Corrosion
    Non uniform corrosion of the surface that causes small pits or craters to develop.
  • Plate
    A hot rolled flat product of rectangular section, typically over 10mm thick. Control of surface finish is less rigorous than for sheet.
    Related Terms: Shate, Sheet
  • Porthole Dies
    Dies that produce extruded hollow products from solid extrusion ingots. They incorporate a mandrel as an integral part of the die assembly and leave one or two ‘weld’ seams along the extrusions.. Bridge, spider, duo and self-stripping dies are particular types of porthole die.
  • Powder Coating
    Application of an even layer of colour to aluminium extrusions by spraying powdered paint using an electrostatic process then baking on (stove enamelling).
  • Pre-Ageing
    A thermal treatment after quenching and before the end of the precipitation incubation period.
  • Precipitation Annealing
    The heating of a quenched and precipitation hardened work piece for some time at a temperature between the artificial ageing temperature and the solution treatment temperature. It produces significant softening by coalescing the hardening precipitates.
  • Precipitation Hardening
    Age Hardening, Ageing
    The second stage in the process (solution treatment and ageing) for those aluminium alloys that respond to heat treatment as a means of increasing their mechanical properties. It entails the precipitation of a constituent from a supersaturated solid solution. The rate of precipitation, and hence ageing, is both temperature and time dependent, with some alloys ageing at room temperature. It is more usual to perform ageing at higher temperatures. It should be noted that routinely operating aged alloys at unusually high ambient temperatures will permit further ageing and even over ageing leading to loss of properties.
  • Precipitation Treatment
    Artificial Ageing
    The thermal treatment of an alloy that increases the hardness and strength by precipitation of constituents from the super-saturated solid solution at above room temperature.
  • Pressure Test
    A hydraulic or pneumatic test for tubes to prove that they material can withstand a specified pressure for a specified time without leakage or rupture.
  • Proof Stress (Rp)
    The stress or applied load which produces a permanent elongation equal to a specific percentage of the original gauge length. In alloys that do not exhibit a yield point it is used as an equivalent to the elastic limit. If a proof stress is specified, the non-proportional elongation must be stated. The most common values used in specifications is 0.2% or 1.0% and the RP symbol used for the stress will be supplemented by an index giving this prescribed percentage of the original gauge length, e.g. RP0.2 = 0.2% Proof Stress.