Choosing a material: grade, temper and product form
Turn a material name into a usable purchasing and manufacturing specification, with stainless and aluminum examples.
On this page
Start with the part, then specify the stock
Specify grade, supplied condition, product form and size together. Match the property and test conditions to the governing product specification and edition. A typical plate value cannot set an extrusion acceptance minimum. Compare the specified minimum with results traceable to the delivered material.
- 6061 temper and product form. Quote T651 stock condition and finished flatness separately. Stretching relieves stress, while stock removal, geometry and restraint affect released-part flatness.
- 304 versus 316. Treat 316 as a candidate for chloride exposure. Check chemistry, temperature, deposits, crevices, stress, weld history and substitution approval.
What belongs in a material description?
Hydro lists minimum tensile and yield strengths of 260 and 240 MPa for its 6061-T6/T6511 extrusions. The section thickness at the tension specimen selects the row. Use the ordered product specification for acceptance. Hydro 6061, rev. 2019/01
Elongation has separate values and specimen exceptions in that producer table.
| Description | What it answers | Example |
|---|---|---|
| Grade | Which alloy or material family? | 6061 aluminum; Type 304 stainless steel |
| Temper or condition | What processing state is supplied? | T6, T651; solution annealed |
| Product form and size | What stock will enter production? | Plate thickness, extrusion section, tube dimensions |
| Specification and certification | What requirements must the supply meet? | Applicable product standard, edition and inspection document |
| Final requirements | What must survive fabrication? | Strength, corrosion performance, dimensions and surface finish |
Example: 6061-T6 versus stress-relieved stock
T6 identifies solution heat treatment and artificial aging. Additional stress-relief suffixes carry information that the shorter T6 label leaves out. Product form matters: plate and extrusion descriptions should not be shortened into one interchangeable purchasing label.
Start with the 6061 comparison and product-form data. Use 6061-T6 for its temper comparison and 6061-T651 for plate and machining considerations. These pages identify the producer documents behind their values.
For a thin-wall part, state the inspection condition for finished flatness. A measurement made under machining restraint can differ from the released result.
Example: 304 versus 316 stainless steel
Both are austenitic stainless steels. Type 316 contains molybdenum and is a candidate where localized corrosion resistance requires more than a basic 304 selection. The environment—not an indoor/outdoor label alone—determines whether either is suitable. Outokumpu distinguishes corrosion mechanisms and grades in its Supra range data sheet.
| Decision question | Reference to read | Information still needed |
|---|---|---|
| Is 304 suitable for the exposure? | 304 corrosion and fabrication | Fluid chemistry, temperature, deposits, crevices and stress |
| Would 316 address the actual corrosion mechanism? | 316 corrosion evidence | Cleaning and upset conditions as well as normal service |
| Does welding make a low-carbon grade relevant? | 304L and 316L | Joint, thermal history, governing specification and final acceptance |
Neither 316 nor a low-carbon suffix is a universal solution to chloride exposure. The detailed references separate intergranular corrosion from pitting and stress-corrosion cracking.
Follow the material through production
For the bracket, use the service environment and drawing to select stock. Check what forming and welding change, then specify finish and inspection before comparing costs.
The connected reading path is material → shaping processes → joining → finishing → inspection methods → cost estimate.
For delivered-material evidence, start with Choosing an EN 10204 inspection document, then read material test reports for identity, test-unit and traceability details.
Sources and scope
This guide synthesizes the linked producer references and detailed wiki articles, checked November 2, 2026 PST. It supplies a selection workflow rather than design allowables, an approved substitution or machine settings.