Room Temperature Torsional Behavior of 15-Cr-15Ni Titanium Modified Austenitic Stainless Steel

This paper reports room temperature torsional behavior of solution annealed 15Cr-15Ni Titanium modified austenitic stainless steel (Alloy D9) up to 200% strain in the strain rate range 0.001-1/s in steps of a decade. Specimens of 10 mm gauge diameter and 25 mm gauge length were used in the tests. Free-end torsion tests maintaining zero axial force on the specimen were carried out till specimen rupture. Acquired torque twist data has been converted to shear stress – shear strain data using Nadai's formulation for torsion of solid bars. At lower strain rates up to 0.1/s the material exhibited periodic hardening and softening till failure. The no. of periods in hardening/softening cycles decreased with increase in strain rates. Serrated flow was observed after a certain strain level.