Positive Material Identification Proves Its Value

How can you tell a Super Duplex Stainless Steel from an Austenitic Stainless Steel, or a Nickel Alloy from a Copper Alloy when they all largely look the same ?

That’s the problem experienced by many of the organisations in the supply chain. Here, Kathy Stubbs, Group Technical & Quality Manager, outlines Langley Alloys approach to positive material identification and ensuring traceability throughout the Langley Alloys supply chain.

“To ensure material traceability, product conformance and to ultimately ensure safety of people and equipment, Langley Alloys employs Positive Material Identification (PMI) on all incoming stock material. Our PMI analysers are pre-loaded with our alloy specifications, enabling us to quickly determine the product grade and verify compliance to the product purchase requirements. Over 99% of the time the results do not give us cause for concern, but occasionally we identify incoming material that appears not to be the correct product – this additional layer of checks over-and-above paperwork, labels and dimensional verification allows us to proactively and confidently challenge the supplier.

A recent example springs to mind.

Another stockist had offered some Aluminium Silicon Bronze to the DefStan (Defence Standard) 02-879 Part 2 Annex D. The material was delivered with suitably-conforming test certification. However, during a routine PMI analysis it was identified that the material was NOT Aluminium Silicon Bronze but in fact Nickel Aluminium Bronze, a very different alloy.

A repeat test of mechanical properties i.e. tensile test, would not have revealed non-conformance due to the very similar properties of the two grades. Two possible means to determine conformance would be either a chemical analysis or a Magnetic Permeability test – neither of which are routinely undertaken by many distributors.

Nb. Aluminium Silicon Bronzes are non-magnetic with a magnetic permeability of < 1.05, whilst Nickel Aluminium Bronze has a magnetic permeability of 1.50.

Langley Alloys were challenged by the supplier as to the validity of the results, but the combination of both PMI and Magnetic Permeability testing provided robust evidence and the incoming material was rejected back against the other distributor.

Whilst supply of material to our customer was delayed as a consequence, this was preferable to inadvertently supplying the wrong alloy to the customer’s critical application.

Investment in PMI detectors and a robust goods-inward process are not exactly sexy, but ensure peace-of-mind and guaranteed traceability through the Langley Alloys supply chain via our Quality Management System.”