= Tensile strength
{title2=$\sigma_t$}
The ultimate <tensile strength> in an ordinary tension test is the maximum applied tensile <force> divided by the specimen's original cross-sectional area:
$$
\sigma_{\rm UTS}=\frac{F_{\max}}{A_0}.
$$
It is the peak <engineering stress>, not necessarily the stress at final fracture and not the same as <yield strength>. A specimen with $A_0=10\,\mathrm{mm}^2$ and peak load $5\,\mathrm{kN}$ has <tensile strength> $500\,\mathrm{MPa}$. Necking reduces the current area, so true stress using that area can behave differently after the engineering-stress peak. <Temperature>, loading rate and specimen preparation belong to the test conditions.https://nvlpubs.nist.gov/nistpubs/TechnicalNotes/NIST.TN.1714.pdf[NIST TN 1714, ultimate tensile strength definition]{ref}
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