In a tensile test, a machined sample is pulled to failure. Three values are normally reported: ultimate tensile strength (UTS, the peak stress), yield strength or 0.2% proof stress (where permanent deformation begins), and elongation (how much it stretched before breaking, a measure of ductility). Values are given in MPa (N/mm²) and percent. Hardness tests such as Webster or Brinell are quicker proxies often used on the shop floor.
Why it matters when buying
- Strength depends on both alloy and temper; the same alloy can vary several-fold between O and fully hardened conditions.
- Standards give minimum values per alloy, temper and thickness or section; check the mill test certificate against them.
- For structural extrusions in 6061 or 6063, under-aged material is a common cause of low results.
- Yield, not UTS, is usually what designers use, so make sure it is reported.
- For wire rod and conductors, tensile range is specified along with conductivity.
Notes
Test direction matters for rolled plate and extrusions, since properties can differ along and across the rolling or extrusion direction. Agree the test standard and sample location in the RFQ.