What is the standard unit used to express yield strength in structural steel?

What is the standard unit used to express yield strength in structural steel?

• A. MPa
• B. Watts
• C. Degrees Celsius
• D. Newtons

Answer: (A)

Yield strength is the stress at which structural steel begins to deform plastically. Stress is force per unit area, so its standard SI unit is pascals, with engineers commonly using megapascals (MPa) for practicality, since steel strengths are in the hundreds of MPa. One MPa equals 1 N/mm^2, which keeps numbers convenient. The other options are units for power, temperature, and force, not stress, so they don’t express yield strength.

Yield strength is the stress at which structural steel begins to deform plastically. Stress is force per unit area, so its standard SI unit is pascals, with engineers commonly using megapascals (MPa) for practicality, since steel strengths are in the hundreds of MPa. One MPa equals 1 N/mm^2, which keeps numbers convenient. The other options are units for power, temperature, and force, not stress, so they don’t express yield strength.