A weld metal has a strength of 500 MPa after a post-weld relief of two hours. If the relief time is extended to four hours, is it likely the weld would still exceed a minimum strength of 480 MPa?

A weld metal has a strength of 500 MPa after a post-weld relief of two hours. If the relief time is extended to four hours, is it likely the weld would still exceed a minimum strength of 480 MPa?

• A. No
• B. It would reach 520 MPa
• C. Yes
• D. It would drop below 480 MPa

Answer: (C)

Relief treatment mainly relieves residual stresses in the weld area, with only a modest effect on the weld metal’s strength. If the weld already tests at 500 MPa, extending the relief time to four hours would more likely cause a small change (often a slight reduction due to tempering, rather than an increase). To drop below the 480 MPa minimum, the strength would have to fall by more than 20 MPa, which is unlikely from just doubling the relief time at typical relief temperatures. Therefore, the weld would still exceed 480 MPa.

Relief treatment mainly relieves residual stresses in the weld area, with only a modest effect on the weld metal’s strength. If the weld already tests at 500 MPa, extending the relief time to four hours would more likely cause a small change (often a slight reduction due to tempering, rather than an increase). To drop below the 480 MPa minimum, the strength would have to fall by more than 20 MPa, which is unlikely from just doubling the relief time at typical relief temperatures. Therefore, the weld would still exceed 480 MPa.