ВК, WCo and YG Hardmetal Grades — How to Verify a Sourcing Request

Why Similar Grade Names Do Not Prove Equivalence

ВК, WCo and YG designations can appear in customer specifications, supplier catalogues and commercial correspondence for tungsten-carbide materials with a cobalt binder. The names may describe related material families, but a name alone does not establish an identical governing standard, carbide composition, binder content, grain size, porosity level, density, hardness, mechanical behaviour or manufacturing route.

For sourcing purposes, MNK-G.S.A treats each proposed cross-reference as a technical comparison that must be supported by the customer’s governing specification, the manufacturer’s current datasheet and batch-level inspection documents.

Five Possible Cross-Reference Outcomes

• Direct standard designation: the same designation is confirmed under the same governing specification and revision.
• Closest material equivalent: the available grade is technically close, but differences remain and customer approval is required.
• Application-group correspondence: the materials may serve a similar cutting or wear application, without being chemical equivalents.
• Common commercial variant: a supplier or market designation describes a related product family but is not itself a standards-based equivalence statement.
• No direct equivalent identified: the available evidence is insufficient or shows a material difference.

Documents to Compare Before Quotation

What the Test Standards Confirm

Reference	What it helps verify	What it does not prove alone
ASTM B890	Metallic constituents of tungsten alloys and hardmetals by XRF	Automatic equivalence to a customer grade
ASTM B311 / ISO 3369	Density by defined test methods	Correct composition merely because density is within a range
ASTM B294	Rockwell HRA hardness under the specified method	Complete grade identity or total application suitability
ASTM B276	Metallographic assessment of apparent porosity	A complete material specification by itself
ISO 4499-1, ISO 4499-2 and ISO 4499-4	Microstructure, WC grain size, porosity, carbon defects and eta phase	Interchangeability without the governing specification

The relevant test method must be specified together with acceptance limits. A test result is supporting evidence; it is not a substitute for the required grade, drawing or product specification.

ISO 513 Application Groups Are Not Grade Equivalents

ISO 513:2012 classifies hard cutting materials and their application groups for metal removal with defined cutting edges. Its scope does not establish chemical equivalence between national or commercial grades, and it does not cover several other hardmetal uses such as percussion tools, drawing dies or tools that work by metal deformation.

Write “typical ISO 513 application-group correspondence” when supported. Do not write “ВК or ТК grade equals ISO P/K/M grade” unless a separate standards-based material equivalence has been established.

Controlled Example: ВК25 / WCo25 / YG25

If a customer requests ВК25 and a manufacturer proposes WCo25 or YG25, MNK-G.S.A does not approve the substitution from the name alone. The review compares the governing specification, declared WC/Co composition, any additional carbides, binder system, density, hardness, grain size, microstructure, porosity, product form, dimensions and batch documentation.

The result may be a direct match, a conditional technical alternative, an application-group correspondence, a commercial variant or no confirmed equivalent. The customer’s specification remains controlling. See the completed ВК25 rods and ТК plates supply case for the sourcing and documentation context of an actual commercial supply.

RFQ Checklist for Hardmetal Grades

• Required grade and governing specification, including revision where known
• Drawing, product form, dimensions, tolerances and surface condition
• Required chemistry, binder content and permitted additional carbides
• Hardness, density, grain-size, porosity or other acceptance limits
• Quantity, inspection-document level and traceability requirements
• Operating or tooling context where substitution approval is requested
• Delivery destination and required date

Related MNK-G.S.A Resources

• ВК and ТК cemented-carbide sourcing
• Hardmetal and tooling sourcing
• MNK Technical Library