The point at which permanent deformation occurs in a tensile test is called?

The point at which permanent deformation occurs in a tensile test is called?

• A. Yield point
• B. Elastic limit
• C. Ultimate tensile strength
• D. Necking point

Answer: (A)

When a specimen is pulled in tension, it stretches elastically at first—the deformation would be reversible if you released the load. As the load increases beyond the elastic limit, the material begins to deform plastically, and some permanent, non-recoverable change remains after unloading. The stress level at which this permanent deformation first appears is the yield point. It marks the transition from elastic to plastic behavior. Some materials show a distinct upper and lower yield point, while for others we use a practical yield strength, such as the 0.2% offset yield, to define when plastic deformation becomes permanent. The ultimate tensile strength is the maximum stress the material can withstand before necking leads to fracture, and the necking point refers to the onset of rapid cross-sectional thinning after yielding.

When a specimen is pulled in tension, it stretches elastically at first—the deformation would be reversible if you released the load. As the load increases beyond the elastic limit, the material begins to deform plastically, and some permanent, non-recoverable change remains after unloading. The stress level at which this permanent deformation first appears is the yield point. It marks the transition from elastic to plastic behavior.

Some materials show a distinct upper and lower yield point, while for others we use a practical yield strength, such as the 0.2% offset yield, to define when plastic deformation becomes permanent. The ultimate tensile strength is the maximum stress the material can withstand before necking leads to fracture, and the necking point refers to the onset of rapid cross-sectional thinning after yielding.