The principles of testing the mechanical properties of metallic materials through the use of the spherical indentation test have been analysed and studied in this paper. The error between the representative indentation stress from spherical indentation and the theoretical stress of the power exponential equation was taken as the convergence condition using the optimization function in Matlab. The yield strength, strain hardening index and elastic modulus were optimized between the stress-strain curve from spherical indentation and the theoretical stress-strain curve of the power exponential equation. The smallest error that could be achieved between them was obtained and from this the mechanical properties of the material could then be calculated and analysed. Q345R steel, which is used for pressure vessels, was taken as an example and the mechanical properties were tested using the spherical indentation test, and the results were compared with the conventional tensile test. Comparative analysis of the mechanical properties of the steel between the results from the spherical indentation test and the conventional tensile test showed that the difference was small. The accuracy of the spherical indentation method when testing the mechanical properties of metallic materials is high. The results have shown that the spherical indentation test can be used as a replacement for the conventional tensile test and can be applied in the field of testing the mechanical properties of Q345R steel for pressure vessels.
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