Question

Structural steel forms neck before it breaks. Neck formation starts

• A. before limit of proportionality
• B. after yield strength
• C. before ultimate strength
• D. at ultimate strength

Hint:

Necking begins after the yield strength, as the material undergoes plastic deformation before breaking.

Answer 1

The Correct Option is B

Step 1: Understand the behavior of steel under stress.
In the stress-strain curve for structural steel, necking occurs after the material has yielded. The material begins to deform plastically after the yield point and necking starts before the ultimate strength. Step 2: Conclusion.
Necking is a localized reduction in the cross-sectional area of the material and begins after the yield point, not at the ultimate strength. Final Answer: \[ \boxed{\text{after yield strength}} \]