The Influence of Loading Paths on Mechanical Behavior and Microstructure of Mn18Cr18N Austenitic Stainless Steel

The mechanical behavior of Mn18Cr18N steel along different loading paths was investigated at room temperature. In compression–tensile loading paths, the strain hardening behavior depends on subsequent tensile loading directions. When the subsequent loading axis coincides with the previous loading axis, the strain hardening path coincides with the strain hardening path in previous strain stage. When the subsequent loading axis changed, the subsequent strain hardening rate is remarkable greater than that in the previous strain hardening stage. The tensile ductility is different along different loading paths. In consecutive compression–tensile loading paths, the tensile ductility increased first and then decreased. Dislocation rearrangement caused good ductility during the tensile loading. In non-consecutive compression–tensile loading paths, the tensile ductility decreased gradually. Dislocation multiplication occurred rapidly during the subsequent tensile loading. Stress hardening is remarkable during compression–tensile consecutive cyclic loading when the strain amplitude is greater than 0.01. The maximum tensile stress can be reached up to 1549.6 MPa at 3 cycles with 0.15 strain amplitude, which is an increase of 395.4 MPa compared to the simple tensile loading. During complex loading paths, dislocation configurations and the substructures not only depend on the accumulated strains but also on the loading paths.