EVALUATING THE MECHANICAL PROPERTIES OF OXIDE DISPERSION STRENGTHENED FERRITIC STEEL USING SMALL PUNCH TESTING TECHNIQUE

The mechanical properties of Oxide Dispersion Strengthened (ODS) ferritic steel were characterized by tensile and Small Punch Test (SPT) techniques. The tensile tests were evaluated in the longitudinal orientation (parallel to the extrusion direction) while the SPT were done in the longitudinal and transverse orientations. The microstructure of the as received and after SP testing were characterized by scanning electron microscopy and electron back-scattering diffraction techniques.

It was found that the yield and ultimate stresses are almost identical in both orientations despite the anisotropic microstructure.

The yield stress measured by tensile test in the longitudinal was 1079 ± 18 MPa and the ultimate stress was 1180 ± 24 MPa. On the other hand, the elongation at the S_uts in the longitudinal is double that of the transverse direction, 20 % and 10 % respectively. The mechanical properties values obtained by SPT were similar to the tensile results.

The as fabricated alloy is characterized by fibrous texture whereas, [110] direction is parallel to the extrusion direction. Fractography revealed that the fracture in the transverse and longitudinal orientations propagated parallel and across to the oriented grains. EBSD examination of the fracture cross section revealed more variants of the [110] orientation accompanied by fragmentation of the fibrous grains.