Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
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Article Citation - WoS: 28Citation - Scopus: 34The Strain Rate Sensitive Flow Stresses and Constitutive Equations of a Selective-Laser and an Annealed-Rolled 316l Stainless Steel: a Comparative Study(Elsevier, 2022) Güden, Mustafa; Enser, Samed; Bayhan, Mesut; Taşdemirci, Alper; Yavaş, HakanThe strain rate dependent compressive flow stresses of a Selective-Laser-Melt 316L (SLM-316L) alloy and a commercial (annealed-extruded) 316L (C-316L) alloy were determined, for comparison, between 1x10-4 and ∼2500 s-1 and between 1x10-4 and ∼2800 s-1, respectively. The Johnson and Cook flow stress material model parameters of both alloys were also determined. The microstructural examinations of the deformed cross-sections of tested specimens (interrupted tests) showed a twinning-induced-plasticity in SLM-316L alloy and a martensitic transformation-induced-plasticity in C-316L alloy. Twin and martensite formations were detected microscopically higher in the dynamically tested specimens until about 0.22 strain, while the twin and martensite formations decreased at increasing strains due to adiabatic heating. The rate sensitivity of SLM-316L was determined slightly higher than that of C-316L within the quasi-static strain rate range (1x10-4 and 1x10-2 s-1), while the rate sensitivities of both alloys were similar in the quasi-static-high strain rate range (1x10-4 and ∼2500-2800 s-1) at low strains. A more rapid decrease in the rate sensitivity of C-316L at increasing strains was found in the quasi-static-high strain rate range. The similar activation volumes of both alloys, corresponding to the dislocation intersections, indicated a similar thermally activated deformation process involvement in both alloys.Article Citation - WoS: 54Citation - Scopus: 59Orientation Dependent Tensile Properties of a Selective-Laser 316l Stainless Steel(Elsevier, 2021) Güden, Mustafa; Yavaş, Hakan; Tanrıkulu, Ahmet Alptuğ; Taşdemirci, Alper; Akın, Barış; Enser, Samed; Karakuş, Ayberk; Arslan Hamat, BurcuThe effect of specimen inclination angle with respect to building direction on the tensile properties of a selective laser melt 316L alloy was investigated. Tensile test specimens were fabricated with the angles between 0 degrees to 90 degrees at 15 degrees intervals using a rotation scanning. In addition, 316L alloy test specimens were generated in the ANSYS 2020R1 additive module and tensile tested in LS-DYNA in order to determine the effect of residual stresses on the tensile strengths. The microscopic analysis revealed a strong < 110 > fiber texture orientation along the building direction (the loading axis of 0 degrees inclined specimens) and a weak 111 texture or nearly random distribution of directions in the normal to the building direction (tensile loading axis of 90 degrees inclined specimens). The yield and tensile strength increased and ductility decreased with increasing inclination angle. The strength variation with the inclination angle was shown well-fitted with the Tsai-Hill failure criterion. Although, the used numerical models indicated an inclination-dependent residual stress, the difference in the residual stresses was much lower than the difference in the strengths between 0 degrees and 90 degrees inclined specimens. Predictions showed a lower twinning stress in 0 degrees inclined specimens due to < 110 > fiber texture orientation in the tensile axis. The fiber texture resulted in extensive twinning; hence, higher ductility and tension-compression asymmetry in 0 degrees inclined specimens. Based on these results, the variations in the strength and ductility of tested SLM-316L specimens with the inclination angle was ascribed to the variations in the angle between the fiber texture orientation and loading axis.