Biaxial deformation and fatigue behavior including notch effects

This study is devoted to investigation of the biaxial deformation and fatigue behavior as well as damages development for both smooth and notched specimens made of a vanadium-based microalloyed (MA) AISI 1141 steel. MA steels have been introduced as an economical replacement for the traditional Quenched and Tempered (Q&T) steels, as they do not require the costly Q&T process. Uniaxial deformation and fatigue behavior had previously been extensively researched and documented. The two notch geometries include stepped shaft and circumferencially grooved round specimens.; The material's monotonic and cyclic deformations under torsion loading were investigated experimentally and analytically. Three commonly used plasticity deformation criteria were used to correlate torsional deformation with the uniaxial deformation behavior. Cyclic axial-torsion deformation tests were also performed and results were correlated with the uniaxial and torsion deformations. Notch root deformations under torsion and axial-torsion loading conditions were analyzed by two analytical models and by using nonlinear FEA. Hoffmann-Seeger and Glinka are the two analytical models used.; The smooth specimen fatigue behavior under torsion and axial-torsion loading conditions were correlated by stress-based, strain-based, and critical plane models. Notch geometry effects on fatigue behavior under torsion and axial-torsion loading conditions were investigated and notched fatigue data were correlated using the aforementioned models for smooth specimen fatigue data. Finally, torsional and axial-torsional fatigue damage development and crack growth behaviors of both smooth and notched specimens were studied through replication techniques and linear elastic fracture mechanics-based models were used to analyze and correlate the acquired crack growth data from smooth specimens.