TY - JOUR A1 - Jiao, Feng A1 - Ă–sterle, Werner A1 - Portella, Pedro Dolabella A1 - Ziebs, Josef T1 - Biaxial path-dependence of low-cycle fatigue behaviour and microstructure of alloy 800 H at room temperature T2 - Materials science and engineering A N2 - Low-cycle fatigue experiments under combined axial-torsional loading have been carried out on alloy 800 H tubular specimens at room temperature. In comparison with proportional loading, an extra cyclic hardening effect produced by nonproportional loading was observed. The microstructure study highlights the fact that the dislocation arrangement under proportional loading is significantly different from that under nonproportional loading. Mechanical twinning was found in specimens cycled under axial loading and nonproportional loading. It is suggested that mechanical twinning depends not only on shear stress but also on normal stress on the plane of maximum shearing. The extra hardening can be interpreted in terms of the deformation microstructure. Fatigue cracking was initiated generally at the specimen surfaces along the plane of maximum shearing, but under nonproportional loading cracks were found also in the bulk of the specimens. Transcrystalline crack propagation was observed in the specimens after proportional and nonproportional LCF tests. PB - Elsevier CY - Amsterdam PY - 1995 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/2503 AN - OPUS4-2503 SN - 0921-5093 SN - 1873-4936 VL - 196 IS - 1 SP - 19 EP - 24 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany