Can the ultimate tensile strength of steels be estimated from the yield strength or 0.2% proof strength values?

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^[1].

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 (σ_y) (in N/mm² units):

UTS/σ_y = 1 + 2 (150/σ_y)^2.5

Fig.1 Determination of σ_y/UTS ratio from yield strength

Examples are given in the table below:

Reference

1. A Bannister: 'SINTAP - Structural Integrity Assessment Procedure for European Industry', Brite Euram Project BRPR950024 Final Report, British Steel Swinden Technology Centre, UK, 1999.