The newly released ISO 6892-1:2016 standard for ambient tensile testing of metallic materials provides greater clarity of the major changes that were introduced in the previous version, ISO 6892-1:2009.
The 2009 version of the standard introduced testing rates based on strain rate (Method A). Method A was based on maintaining a strain rate around the area of interest (yield), whereas traditional testing was based on having a constant stress rate during the elastic region (Method B). As some metals are strain-rate sensitive, Method A provides improved repeatability and allows for more comparable results by reducing the variation of test rates at the time when strain-rate sensitive parameters are determined. The introduction of Method A caused confusion. Many understood this as only being achievable by using equipment capable of closed-loop strain control, but this is not true. It is possible to conform to Method A of ISO 6892-1:2009 by using a constant crosshead speed.
To better clarify, the requirements of Method A, ISO 6892-1:2016 now includes two clearly defined approaches, Method A1 (closed-loop strain control) and Method A2 (constant crosshead separation rate).
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