One material, several designations
A drawing may show 1.4404, a purchasing email 316L and a certificate S31603. These references help identify the alloy, but do not individually define every technical requirement of an order. A European material number, AISI/Type name and UNS number are identification systems. Whether the product is bar, plate, pipe or a forging influences the applicable standard and acceptance requirements.
A cross-reference table speeds up the initial search. Chemistry limits, mechanical properties, supply condition and testing must still be checked against the relevant specification. Assuming adjacent designations in a table are interchangeable in every product form creates ambiguity. If dual compliance is required, it needs explicit documentary confirmation.
Read four separate pieces of information together
Grade identity identifies the alloy requested. A technical delivery specification sets material and test requirements for products within its scope. A dimensional standard defines geometric acceptance. Document standards such as EN 10204 classify the inspection document supplied. None replaces the others.
For example, requesting a 17-4 PH bar with a 3.1 certificate does not define its ageing condition. The applicable product specification, delivery condition, section and additional testing are still needed. With specifications such as AMS, check that the number applies to the required product form and material condition; citing an aerospace specification does not by itself establish approval of the entire supply chain.
Build a complete purchase description
Carry the drawing’s specification revision and customer supplements into the enquiry. The latest edition may differ from the edition required by an existing project. Where requirements conflict, clarify precedence before quotation. On receipt, check the order, certificate and batch markings together rather than relying solely on the abbreviated grade on a label.
- Grade / material number and product form
- Required specification, revision and delivery condition
- Dimensions, tolerances, quantity and inspection document