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ECO-index

ECO-index
Definition:One of the indicator of mechanical properties taking into account the tensile strength and elongation.
Explanation:Since it is difficult to draw conclusions on material behavior by a single characteristic value of strength or elongation, the ECO-index is introduced. It is defined as the product of ultimate tensile strength (UTS) and uniform elongation (El), which results in the unit GPa %:
ECO-index=UTS × El. With combining the strength and formability into a single parameter, the ECO-index gives a rough estimation of the overall performance of a material. The values of the ECO-index are usually limited to max. 20 GPa % in advanced high strength steels ( →AHSS); but typical high Mn steels exceeds such value significantly.
Picture /
Figure /
Diagram:

ECO-index of high strength sheet steels for automotive application; the austenite volume percent is shown together. Especially in HMnS, different deformation mechanisms may be responsible for the extraordinary mechanical behavior.
References:Bleck,W.: HMnS 2011, Seoul, Korea,