Nickel Alloy Scrap Glossary

122 terms, A to Z

Quick Answer

The words used every day in the nickel alloy and superalloy scrap trade, defined in plain language: alloys, forms, testing, metallurgy, standards, documents and trade terms.

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Overview

The Glossary at a Glance

Terms by category, and two pictures that explain a lot of them.

Face-centred cubic (FCC)Nickel alloys, austenitic stainless. Non-magnetic, ductile.

Hexagonal close-packed (HCP)Titanium at room temperature. Lighter, about 4.5 g/cm³.

The two crystal structures met most often in this trade. Illustrative, not to scale.

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2.2 test reportDocuments

An EN 10204 type 2.2 document in which the manufacturer states that the product complies with the order, with results from non-specific inspection rather than from the delivered batch.

3.1 certificateDocuments

An inspection certificate issued under EN 10204 type 3.1, reporting test results on the delivered batch and validated by an inspector independent of the manufacturing department.

3.2 certificateDocuments

An EN 10204 type 3.2 certificate, validated both by the manufacturer’s independent inspector and by the purchaser’s or a third-party inspector.

A

Age hardeningMetallurgy

Strengthening an alloy by holding it at an intermediate temperature so that fine particles precipitate inside the grains. Also called precipitation hardening.

Alloy 625Alloys

The generic name for Inconel 625, UNS N06625: a nickel-chromium-molybdenum-niobium alloy with about 9% molybdenum and 3.6% niobium.

Alloy 718Alloys

The generic name for Inconel 718, UNS N07718: a precipitation-hardened nickel-chromium-iron alloy with about 5% niobium.

Alpha-beta titaniumAlloys

A titanium alloy containing both the hexagonal alpha phase and the cubic beta phase. Titanium Grade 5 (Ti-6Al-4V) is the most common example.

AMSStandards

Aerospace Material Specifications: the specification series used for aerospace bar, sheet, forgings and castings, such as AMS 5662 for Inconel 718 bar.

AnnealingMetallurgy

Heating metal and cooling it in a controlled way to soften it, relieve stress or dissolve precipitates. Solution annealing is the form used on most nickel alloys.

ASME SBStandards

The ASME Boiler and Pressure Vessel Code versions of ASTM B specifications. ASME SB-444, for example, mirrors ASTM B444.

ASTM AStandards

The ASTM specification series for iron and steel products, including duplex and super-austenitic stainless grades such as A240 and A790.

ASTM BStandards

The ASTM specification series for non-ferrous products, which covers nickel alloy plate, pipe, tube and bar, such as B443 for alloy 625 plate.

AusteniticMetallurgy

Having a face-centred cubic crystal structure at room temperature. Nickel alloys and 300-series stainless steels are austenitic and therefore essentially non-magnetic.

B

Balance elementMetallurgy

The element that makes up the remainder of a composition after the listed alloying elements. In Inconel 625 the balance is nickel; in Incoloy 825 it is iron.

Bar endsForms

Short offcuts left when round, hex or flat bar is cut to length. They are among the easiest scrap to prove because heat numbers are often still visible.

Base metalMetallurgy

The element present in the largest amount, which defines the alloy system: nickel-base, iron-base, cobalt-base or titanium-base.

BatchTrade

A quantity of scrap packed and described together. A good batch is one grade, one form and one condition.

Bill of ladingDocuments

The transport document issued by the shipping line for a sea shipment. It acts as a receipt for the cargo and as the document of title.

BladeForms

A turbine blade: the rotating aerofoil in a gas turbine. Retired blades are a major source of cast superalloy revert.

BriquettesForms

Turnings compressed into dense blocks. They oxidise less and are easier to charge and sample than loose chips, but not every melter wants them.

Burning skeletonForms

The frame of plate left after profile cutting, with the cut-out shapes removed. A common form of nickel alloy plate scrap.

C

CarbideAlloys

In scrap, cemented tungsten carbide: tungsten carbide grains bonded with cobalt, used for inserts, drills and dies. In metallurgy, a hard compound of carbon with a metal.

Cast superalloyAlloys

A nickel superalloy made by investment casting rather than by rolling or forging. René 80, MAR-M 247 and GTD-111 are cast alloys.

Certificate of originDocuments

A document stating the country in which the goods were produced or generated. Required by many importing countries for scrap.

CIFTrade

Cost, insurance and freight: an Incoterm under which the seller pays carriage and insurance to the named destination port.

Clad pipeForms

Carbon steel pipe with a corrosion-resistant layer, often alloy 625 or 825, bonded or weld-overlaid on the inside. It must be declared, because the alloy can be a small share of the weight.

ClippingsForms

Small pieces of sheet trimmed during fabrication. Usually sold with plate and sheet scrap.

CoatingForms

A surface layer on a part, such as the aluminide or thermal-barrier coatings on turbine blades. Coated and uncoated revert are kept apart.

Commercially pure titaniumAlloys

Unalloyed titanium, sold as Grades 1 to 4. Grades differ mainly in oxygen and iron content, which XRF cannot fully resolve.

Composite sampleTesting

A sample built from many small portions taken across a lot, used to analyse forms such as turnings that cannot be tested piece by piece.

Contained metalTrade

The weight of each element inside a lot, calculated from the lot weight and its composition. The starting point for valuing nickel alloy scrap.

ContaminationTrade

Any material in a lot that is not the declared grade: other alloys, oil, moisture, coatings, dirt or attachments.

CropsForms

Ends cut off plate, bar or forgings during production. Plate crops and bar crops are common clean scrap forms.

Crystal structureMetallurgy

The regular arrangement of atoms in a metal. Nickel alloys are face-centred cubic; titanium is hexagonal close-packed at room temperature.

D

Decontamination declarationDocuments

A written statement that material from chemical or process plant has been cleaned of hazardous residues. Often required before chemical-plant scrap can ship.

DensityMetallurgy

Mass per unit volume, in g/cm³. Nickel alloys sit around 7.9 to 9.2 g/cm³; titanium is about 4.5 g/cm³, which makes a quick density check useful.

Directionally solidifiedMetallurgy

A casting made so that the grains grow in one direction along the blade, removing grain boundaries across the load. René 108 and GTD-111 DS are examples.

Duplex stainless steelAlloys

Stainless steel with roughly equal parts austenite and ferrite. Duplex 2205 and super duplex 2507 are the main grades. Duplex is magnetic.

E

EN 10204Standards

The European standard that defines types of inspection documents for metallic products, including the 2.2 test report and the 3.1 and 3.2 certificates.

End millForms

A rotating cutting tool, often made of tungsten carbide. Worn end mills are a common form of carbide scrap.

Exotic alloyAlloys

A trade term for high-value special materials handled alongside nickel alloys, such as titanium, tungsten carbide, duplex stainless and Ni-Resist.

F

Face-centred cubic (FCC)Metallurgy

A crystal structure with atoms at the corners and face centres of a cube. It is ductile and non-magnetic in nickel alloys, and the matrix of every Inconel and Hastelloy.

FerriteMetallurgy

The body-centred cubic, magnetic phase of iron. Its presence is why duplex stainless steels attract a magnet.

FOBTrade

Free on board: an Incoterm under which the seller delivers the goods on board the vessel at the named port of loading.

ForgingsForms

Parts shaped by hammering or pressing hot metal, such as discs, rings and shafts. Rejected and retired forgings are a source of solid scrap.

Foundry revertForms

Cast superalloy scrap from the foundry itself: gates, risers, runners and rejected castings that never entered service.

G

Gamma double prime (γ″)Metallurgy

An ordered Ni₃Nb phase that strengthens Inconel 718 and some related alloys.

Gamma prime (γ′)Metallurgy

An ordered Ni₃(Al,Ti) phase that strengthens superalloys close to their melting point. Aluminium and titanium form it.

Gates and risersForms

The channels and reservoirs that feed molten metal into a casting. They are cut off after casting and become foundry revert.

GDMSTesting

Glow-discharge mass spectrometry: a laboratory method that measures trace elements at parts-per-million levels in solid metal.

GradeTrade

A specific alloy within a family, identified by its composition and usually a UNS number. Inconel 625 and Inconel 718 are two grades of the Inconel family.

Grade callTesting

The grade an analyser or inspector assigns to a piece from its readings. A record should keep the readings, not just the call.

Grain boundaryMetallurgy

The interface between two crystals in a metal. Tramp elements collect there and weaken nickel alloys.

H

HastelloyAlloys

A family of nickel-molybdenum and nickel-chromium-molybdenum alloys built for acids and chlorides, including C-276, C-22, B-2 and X.

Heat numberDocuments

The identification number of a melt of metal, stamped or stencilled on the product. It links a piece to its mill certificate.

Heat tintMetallurgy

Colours that form on a metal surface when it is heated in air, from straw through bronze to blue, caused by thin oxide films.

Hexagonal close-packed (HCP)Metallurgy

A crystal structure with atoms in stacked hexagonal layers. Titanium is HCP at room temperature.

HS codeTrade

The Harmonized System customs code. Nickel waste and scrap ships under 7503.00, stainless under 7204.21 and titanium under 8108.30.

I

ICP-OESTesting

Inductively coupled plasma optical emission spectrometry: a laboratory method that dissolves a sample and measures its elements with high accuracy.

IncoloyAlloys

A family of iron-nickel-chromium alloys, such as Incoloy 825 and 925, with iron rather than nickel as the balance element.

InconelAlloys

A family of nickel-chromium alloys used for heat and corrosion resistance, including 600, 625 and 718.

IncotermsTrade

Standard trade terms that define who pays for and bears the risk of carriage, insurance and customs, such as FOB and CIF.

InsertsForms

Small indexable cutting tips, usually tungsten carbide, clamped into a tool holder. Used inserts are sold as carbide scrap.

Investment castingMetallurgy

Casting into a ceramic shell built around a wax pattern. The process used for turbine blades and vanes.

L

Light elementsTesting

Elements lighter than titanium, such as aluminium, silicon, magnesium and carbon. Handheld XRF reads them poorly or not at all.

LotTrade

A quantity of scrap offered or sold as one unit, described by grade, form, condition and weight.

Lot descriptionTrade

The written description of a lot: grade with UNS number, form, condition, weight, identification method and documents.

M

Magnet testTesting

Checking whether a piece attracts a magnet. It separates magnetic steels and duplex from non-magnetic nickel alloys but cannot tell one nickel alloy from another.

MAR-MAlloys

A family of cast superalloys: nickel-base MAR-M 246 and MAR-M 247, used for turbine blades and integral wheels, and cobalt-base MAR-M 509, used for nozzle guide vanes.

Melt shopTrade

A plant that remelts scrap and virgin metal into new alloy. Its chemistry limits set what scrap it can accept.

Mill test certificate (MTC)Documents

The certificate issued by the producing mill with the chemistry and tests of a heat of material.

Mixed lotForms

Scrap of unknown or mixed grades. It is worth less than sorted material until it is identified and segregated.

MonelAlloys

A family of nickel-copper alloys with about 30% copper, mainly Monel 400 and the age-hardenable Monel K-500.

N

NACE MR0175 / ISO 15156Standards

The standard that sets material requirements for equipment in sour, H₂S-containing oil and gas service.

Ni-ResistAlloys

Austenitic cast iron with about 15 to 35% nickel, used for pump casings, impellers and valve bodies.

Nickel alloyAlloys

An alloy in which nickel is the base element, or a major element at roughly 30% or more.

Nickel equivalentTrade

A way of expressing a scrap lot’s value relative to its contained nickel. Not every buyer uses it.

NimonicAlloys

A family of nickel-chromium alloys used in turbines and engine valves, including Nimonic 75, 80A and C-263.

Nominal compositionMetallurgy

The typical or mid-range composition of a grade, used for identification. Specifications set ranges, not single values.

O

OESTesting

Optical emission spectrometry. Spark OES burns a small spot on a ground surface and measures carbon, boron and light elements along with the metals.

OffcutsForms

Pieces left over after material is cut to size, from pipe, plate or bar.

Oil contentTrade

The amount of cutting oil or coolant on turnings. It is usually the main reason turnings are discounted against solids.

P

Packing listDocuments

A document listing each package in a shipment with its contents and weights.

Payable elementTrade

An element a buyer pays for in a scrap lot, such as nickel, molybdenum, cobalt, niobium, tungsten, tantalum or rhenium.

Pipe spoolForms

A prefabricated section of piping with flanges and fittings. Spool fabrication leaves pipe offcuts that are a common scrap form.

PMITesting

Positive material identification: checking and recording that each piece is the grade it is declared to be, usually with XRF or OES.

PMI reportDocuments

The record of a PMI check: lot, instrument, sampling plan, readings and results.

Precipitation hardeningMetallurgy

See age hardening. Used for Inconel 718, Monel K-500, Nimonic 80A and γ′ superalloys.

PSICDocuments

Pre-shipment inspection certificate. India requires one for imports of metallic scrap.

PunchingsForms

Small pieces punched out of sheet during fabrication.

R

Radiation-free certificateDocuments

A certificate that a scrap consignment has been checked and shows no radiation above background. Required by many importing countries.

RecoveryTrade

The share of a scrap lot’s metal that ends up in the new melt after losses to oxidation, slag and contamination.

RemeltingTrade

Melting scrap back into new alloy. Superalloy revert is usually remelted under vacuum.

RenéAlloys

A family of nickel superalloys for turbine hot sections, including cast René 80, René 108, René 125 and single-crystal René N5.

RevertForms

Superalloy scrap that goes back to the melt, either foundry revert or service revert.

RheniumMetallurgy

A rare, heavy element added to the strongest single-crystal superalloys. Rhenium-bearing revert is kept apart from everything else.

S

SegregationTrade

Keeping scrap separated by grade and form from the point it is generated. The single biggest factor in its value.

Service revertForms

Superalloy parts that have run in an engine, such as blades, vanes and nozzles. They may be coated, oxidised or repaired.

Single crystalMetallurgy

A casting grown as one crystal with no grain boundaries, used for the highest-temperature turbine blades.

Solid solutionMetallurgy

An alloy in which the added elements sit on the lattice of the base metal without forming separate phases. Inconel 625 and Hastelloy C-276 are solid-solution alloys.

SolidsForms

Heavy, compact pieces of scrap such as forgings, castings and machined parts. The reference form against which other forms are valued.

Sour serviceStandards

Oil and gas service in the presence of hydrogen sulphide, where materials must resist sulphide stress cracking.

SpecificationStandards

A document that sets requirements for a product form, such as chemistry ranges, mechanical properties and tests. ASTM B443 is a specification.

SpectrometerTesting

An instrument that measures the elements in a material from the energy or wavelength of the radiation it emits.

Super duplexAlloys

Duplex stainless steel with about 25% chromium, such as 2507 (S32750) and S32760, for seawater and offshore service.

Super-austenitic stainlessAlloys

Austenitic stainless steel with high molybdenum and nitrogen, such as 254 SMO with about 6% molybdenum.

SuperalloyAlloys

A nickel, cobalt or iron-nickel alloy designed to keep its strength close to its melting point, mainly for gas turbines.

SwarfForms

Another word for turnings: the chips produced by machining.

T

TantalumMetallurgy

A heavy refractory element added to some cast superalloys. It is valuable and must be confirmed by analysis.

Titanium scrapAlloys

Commercially pure and alloyed titanium, kept completely apart from nickel alloys and from carbide tool fragments.

TraceabilityDocuments

The ability to link a piece back to its heat and mill certificate through markings and records.

Tramp elementsMetallurgy

Unwanted trace elements such as lead, bismuth, tin and selenium that weaken nickel alloys even at parts-per-million levels.

TurningsForms

Chips and swarf from machining nickel alloys. Discounted for oil, moisture, oxidation and grade mixing.

U

UNS numberStandards

The Unified Numbering System identifier: one letter and five digits, such as N06625 for Inconel 625. N is for nickel alloys.

V

Vacuum induction melting (VIM)Trade

Melting metal by induction under vacuum, the usual route for remelting superalloy revert and producing high-purity nickel alloys.

VaneForms

A stationary aerofoil in a gas turbine that directs gas onto the blades. Retired vanes are a source of service revert.

W

W.Nr. (Werkstoff number)Standards

The German material number, such as 2.4856 for alloy 625. Numbers starting with 2 are heavy non-ferrous metals; 1 is steel; 3 is light metals such as titanium.

Weighbridge weightTrade

The weight recorded on a certified weighbridge. It governs the transaction, not a calculated or estimated weight.

Weld overlayForms

A layer of corrosion-resistant alloy, often 625, welded onto a carbon steel surface. Overlaid parts must be declared and sorted separately.

Wire scrapForms

Welding wire, spring wire, coil ends and rod offcuts.

X

XRFTesting

X-ray fluorescence. A handheld XRF analyser reads elements from titanium upward in seconds without marking the part.

Yield (melt yield)Trade: The weight of good metal produced from a charge, as a share of what was charged. Clean, dry, sorted scrap gives a higher yield.

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Nickel Alloy Scrap Glossary

The Glossary at a Glance

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