The Variation in Results of Standardized Tests to Determine the Yield Strength of Structural Steel

Independent tests of mill-certified structural steel have obtained yield strengths which differ significantly from those reported by the mill. A study to identify the causes of this discrepancy focuses on the standardized test procedures employed to determine yield strength and includes a review of published material related to yield point phenomena and mechanical testing, a comparison of ASTM Standards with foreign and international standards, and an experimental program to evaluate the significance of the various test parameters on yield strength determination. Test results indicate that the variation in yield strength due to the use of different machines and testing speeds may account for only a small portion of the reporteddiscrepancy between mill certificates and independent tests.