Browsing by Subject "Strain rate"
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Item High strength and high ductility behavior of 6061-T6 alloy after laser shock processing(Elsevier Ltd, 2016) Gencalp Irizalp S.; Saklakoglu N.The plastic deformation behavior of 6061-T6 alloy which was subjected to severe plastic deformation (SPD) at high strain rates during laser shock processing (LSP) was researched. In LSP-treated materials, the near surface microstructural change was examined by TEM and fracture surfaces after tensile testing were examined by SEM. An increase in strength of metallic materials brings about the decrease in ductility. In this study, the results showed that LSP-treated 6061-T6 alloy exhibited both high strength and high ductility. TEM observation showed that stacking fault (SF) ribbon enlarged, deformation twins formed and twin boundary increased in LSP-treated 6061-T6 alloy. This observation was an indication of stacking fault energy (SFE) decrease. Work hardening capability was recovered after LSP impacts. © 2015 Elsevier Ltd. All rights reserved.Item Experimental Investigation of Impact Behaviour of RC Slab with Different Reinforcement Ratios(Springer Verlag, 2020) Yılmaz T.; Kıraç N.; Anil Ö.; Erdem R.T.; Kaçaran G.Reinforced concrete (RC) slabs may be exposed to the low-velocity impact load during their service periods. In low-velocity impact scenarios, the effect of strain rates has been remarkably higher than quasi-static loading because the loading duration is very short. Thus, structural responses and failure modes will be different. The present study aims to investigate dynamic response and failure modes of simply supported two-way RC slabs exposed to low-velocity impact load. In the experimental part of this study, nine RC slabs with the dimension of 1,000 × 1,000 × 80 mm were tested. The reinforcement ratio of RC slabs and the input impact energy applied to RC slabs were experimental variables investigated. A drop-weight test setup was utilized to apply impact load to RC slabs. By varying drop-height as 1,000, 1,250 and 1,500 mm, three different impact energies have been applied to RC slabs via a hammer of which weight is 84 kg. The time histories of the accelerations, displacements and impact loads were recorded. The dynamic responses obtained by tests and the failure modes observed has been interpreted in detail. Besides, a finite element model where explicit dynamic analysis is performed has been established for verification of the experimental results. There was observed good accordance between numerical and experimental results. Consequently, it is considered that the present finite element treatment can be used for the evaluation of the dynamic responses and failure modes of RC slabs exposed to low-velocity impact load. © 2019, Korean Society of Civil Engineers.Item Influence of Laser Peening With and Without Coating on the Surface Properties and Stress Corrosion Cracking Behavior of Laser-Welded 304 Stainless Steel(Springer, 2021) Gencalp Irizalp S.; Koroglu B.K.; Sokol D.This study aims to investigate the effect of laser peening with (LP) and without coating (LPwC) process on subsurface microstructural evolution, mechanical properties, and stress corrosion cracking (SCC) of laser-welded samples fabricated using 304 stainless steel. SCC behavior of this steel has been studied by the slow strain rate test in air and 3.5wt pct NaCl + 0.5 mol/L H2SO4 solution. Microhardness profiles and metallographic microstructures of the peened and unpeened samples presented and compared. Martensitic transformation is observed by XRD on the surface layer of the peened and unpeened samples. These improvements correlate with the formation of dense deformation bands and work hardening effects resulting from high strain plastic deformation. In unpeened specimens, tensile-type residual stresses arising from the welding process occur. In addition, the LPwC process also induces tensile-type residual stress on the surface. The tensile-type residual stresses on the weld metal and base metal surface as a result of thermal effect are not disruptive for SCC performance because the mechanical effect of LPwC produces an extremely strong work hardening layer just below the surface. As a result, although LPwC offers a combined effect of thermal and mechanical effects on the material, it is an effective and useful method in terms of both mechanical performance and corrosive behavior. © 2021, The Minerals, Metals & Materials Society and ASM International.Item Prediction of Flow Behavior and Deformation Analysis of AA5754 Sheet Metal at Warm and Hot Temperatures(Springer, 2024) Şen N.; Civek T.; İlhan Ö.; Erdem Yurt Ö.; Çetin M.H.; Şimşir H.The utilization of lightweight materials such as AA5754 aluminum alloys in the inner body panel parts of vehicles has been significantly important for automotive manufacturers to minimize the high fuel consumption by reducing the overall weight. In this study, the flow behavior of AA5754 sheet metal has been discussed by conducting uniaxial tensile tests at five different temperatures (RT, 200, 250, 300, 350 °C) and three strain rates (0.001, 0.01, 0.05 s−1). Additionally, the capability of Fields and Backofen (F&B) and Voce hardening rules in describing the flow behavior of AA5754 at different temperatures and strain rates has been investigated by conducting uniaxial tensile tests in finite element analysis. It has been found that the main deformation mechanisms for the AA5754 are the strain hardening mechanism up to 250 °C, strain hardening and dynamic recovery mechanisms at 300 °C, dynamic recrystallization and strain hardening mechanisms at 350 °C. While the F&B hardening rule has been able to successfully capture the flow behavior of AA5754 up to 250 °C with a 14.36% error, its capability has significantly reduced after 250 °C due to its incapability of describing the effects of dynamic recovery and recrystallization. Voce hardening model has been better able to describe the flow behavior of AA5754 at all the temperature levels than F&B model due to its saturation behavior. © ASM International 2023.