Cobalt Alloy Scrap Specification — Stellite-Type, Superalloy and Hardfacing Arisings

Cobalt is rarely used as a pure metal in engineering service. Almost all cobalt-bearing scrap is an alloy in which cobalt is the base or a major constituent, combined with chromium, tungsten, molybdenum, nickel and carbon in ratios chosen for wear resistance, hot strength or corrosion behaviour. The commercial consequence is that a cobalt lot is really a collection of alloy families, and the family determines both the recovery route and the value.

Typical industrial sources are valve trim and seats, pump and compressor wear parts, hot-section turbine components, saw tips and hardfacing overlays, chemical process hardware, and manufacturing arisings from companies that machine cobalt-base bar and castings.

Chemistry is grade-dependent. This page does not state a guaranteed composition: alloy family, element ranges and any deleterious-element limits must be confirmed for the specific lot by material identification, XRF or OES analysis, mill certificates where available, or an agreed inspection before shipment.

Material is offered in one or more of the presentations below; where a lot spans several of them, each form is packed and described as its own fraction.

The following families circulate in the trade. Trade names are used descriptively here to indicate the family a piece belongs to; they are not a claim about the specific chemistry of any lot offered or supplied.

Cobalt-base wear alloys are hard, largely non-magnetic and noticeably resistant to filing and grinding compared with stainless steel of similar appearance. They are dense but not dramatically so, which means density alone does not identify them; instrument screening is the practical route. Chromium and tungsten or molybdenum read strongly on a handheld analyser and are a good first indication of family.

Hardfacing is the recurring grading problem. A hardfaced valve or shaft is mostly steel by weight with a thin cobalt-base overlay, so it cannot be valued as a cobalt-base solid. Where hardfaced items are included they are packed and described separately, and the basis on which they are evaluated has to be agreed before shipment rather than assumed.

Mixed-family lots are graded down not out of caution but because the buyer's remelt or recovery route usually requires a known input window. A lot that has been separated by family at source and labelled accordingly is materially easier to place.

The items below are what typically reduces the recoverable value of a lot or, at the end of the list, keeps it out of the stream altogether.

Cobalt-base material has a high value density, so packing discipline is about traceability as much as protection. Small, well-labelled, securely closed packages allow the lot to be verified at several points along the chain without repacking.

An enquiry is answerable when it states the alloy family (or that it is unknown), whether hardfaced items are included and at what approximate share, the physical forms and weight split, the origin process, whether documentation or analysis exists, and the destination.

Where the buyer requires an assured cobalt content, that value and the way it will be verified — sampling protocol, method, laboratory, acceptance criteria, deduction mechanics — must be written into the sales contract. Indicative discussion before contract is not a specification.

Screening on cobalt-base material is used to assign a piece to a family — cobalt-chromium-tungsten, cobalt-chromium-molybdenum, nickel-base with cobalt — and to detect steel substrates hiding under an overlay. It is reliable for that purpose on a clean, prepared surface and unreliable for anything finer.

Contractual analysis is a different exercise. On hardfaced or clad material a surface reading is systematically misleading, because it reads the overlay rather than the piece. Where such material is contractually significant, the parties should agree a destructive or melt-based sampling method rather than relying on surface screening.

Customs classification for cobalt-bearing secondary material depends on the actual composition and physical form of the goods, on whether the material is solid scrap, turnings, powder or residue, on the destination country and on how the competent authority in that jurisdiction interprets the material description.

Mixed-grade and mixed-family lots can create additional classification complexity, because the description of the goods on the invoice and packing list must reflect what is actually shipped rather than the best fraction in the load.

Nautica does not assign a definitive tariff code in advance for this stream. Buyers and importers should confirm the applicable classification, duty treatment and any import licensing or waste-shipment obligation with their own customs broker or the competent customs authority for the destination before contracting.