Tensile strength is the stress at which condition?

• A. At yield
• B. At maximum strength before necking
• C. At proportional limit
• D. At fracture

Answer: (B)

Tensile strength, typically called the ultimate tensile strength, is the maximum engineering stress a specimen carries in a uniaxial tensile test before necking begins. On a stress–strain curve, the material behaves elastically at first, then yields when plastic deformation starts. As you continue to stretch it, the material work-hardens and the engineering stress rises to a peak. That peak marks the onset of necking, after which the sample’s cross-sectional area shrinks and the engineering stress drops even though the material may still be carrying load, until fracture occurs. So tensile strength is the stress at the maximum load reached, not the yield point, not the proportional limit, and not the fracture stress. In many cases, especially for ductile materials, the UTS occurs before fracture and is the standard reference for tensile strength.