Certification Terms

Sep 5, 2020 | Steel

Many of you have asked about definitions for items listed on the material certification. While there is no standard for reporting either elements or mechanical properties, Steel Supply requires full testing be performed on all of our incoming materials. This allows our inside sales representatives to let you know the properties, as well as the chemistry, on all of our items. It should be noted that different products only require certain values to be reported. If additional testing that is not available from the producing mill lab is required, we have a local source that does all of our testing and has an engineer verify the results. Here are some common terms:

Tensile Strength:
The maximum load per unit of original cross-sectional area obtained before rupture of a tensile specimen.

Yield Strength:
The stress at which a material exhibits a specified deviation from proportionality of stress and strain. An offset of 0.2% is typically used for metals.

The increase in length of a test specimen after rupture in a tensile test, expressed as a percentage of the original length.

Reduction of Area:
The difference between the original cross-sectional area of a tensile specimen and that of the smallest area at the point of rupture.

Brinell Hardness Test:
This test consists of forcing a ball of standard diameter into the specimen under standard pressure, and then judging the hardness by the amount displaced.

Jominy End-Quench Test:
Mostly used on alloy grades, this test heats one end to a quenching temperature and then sprays water on that end which provides a rapid rate of cooling, with progressively slower cooling all the way to the other end.

Charpy Test:
This determines the notched toughness, or impact strength, of a material – usually 17-4PH Stainless Steel but also some alloys. The test gives the energy in foot pounds required to break a standard notched specimen supported at the two ends.

These tests are defined in material standards and we’ll be happy to share any information within our capabilities. The best method for any specific requirement is to have the sample tested at the independent lab.