What does the STRA test measure?

It measures through thickness ductility of a steel plate (the Z direction). STRA stands for short transverse reduction area. Steels with low STRA are commonly associated with a high level of rolled sulphide or oxide inclusions and there is no grade of steel prone to lamellar tearing like steels with low STRA.

The general rule states that steels with STRA over 20% are resistant to tearing while steels with less than 10 to 15% STRA should be used only in lightly restrained joints. Steel suppliers can provide steel that have been through thickness test with STRA value of over 20%.