Ultimate Tensile Strength

The ultimate tensile strength (UTS) is the maximum resistance to fracture. It is equivalent to the maximum load that can be carried by one square inch of cross-sectional area when the load is applied as simple tension. It is expressed in pounds per square inch.

If the complete engineering stress-strain curve is available, as shown in Figure 3, the ultimate tensile strength appears as the stress coordinate value of the highest point on the curve. Materials that elongate greatly before breaking undergo such a large reduction of cross-sectional area that the material will carry less load in the final stages of the test (this was noted in Figure 3 and Figure 4 by the decrease in stress just prior to rupture). A marked decrease in cross-section is called “necking.” Ultimate tensile strength is often shortened to “tensile strength” or even to “the ultimate.” “Ultimate strength” is sometimes used but can be misleading and, therefore, is not used in some disciplines.