There may be situations where yield or proof strength values of steel are known, but ultimate tensile strength (UTS) values have not been reported. As the knowledge of UTS is important for quantifying strain-hardening properties, an estimation scheme has been developed under the European project SINTAP.
Within SINTAP, a large number of data were collected for different steels. The data are shown in Fig.1. The conservative fit to these data leads to the following relationship between the lower bound estimate of UTS and yield or proof strength (σy) (in N/mm2 units):
UTS/σy = 1 + 2 (150/σy)2.5
Fig.1 Determination of σy/UTS ratio from yield strength
Examples are given in the table below:
|σy (N/mm2)||Lower bound estimate of UTS (N/mm2)|
- A Bannister: 'SINTAP - Structural Integrity Assessment Procedure for European Industry', Brite Euram Project BRPR950024 Final Report, British Steel Swinden Technology Centre, UK, 1999.