7 results
Search Results
Now showing 1 - 7 of 7
Article Citation - WoS: 4Citation - Scopus: 4Simulation of Through-Hardening of Sae 52100 Steel Bearings - Part Ii: Validation at Industrial Scale(Wiley-v C H verlag Gmbh, 2016) Evcil, G. E.; Mustak, O.; Simsir, C.In this study, the material dataset presented in part I of this article is validated at industrial scale in batch through-hardening of bearing races. The material dataset acquired is implemented in a commercial heat treatment simulation software. Heat transfer coefficients for the oil and salt bath are determined by using a commercial standard quench probe. Zone temperatures and transfer times of the roller-belt furnace are measured directly from the system. Through-hardening of inner ring (IR) of 6813 bearing in oil and salt bath is simulated considering most of the industrial details. Finally, predicted dimensional changes are compared with the coordinate measurement results and a good agreement is achieved. It is concluded that determined material and process data, idealizations and simulation procedure can be considered "validated" for further improvement of the industrial process.Article Citation - WoS: 69Citation - Scopus: 78An Experimental Study on Channel Type Shear Connectors(Elsevier Sci Ltd, 2012) Baran, Eray; Topkaya, CemThis paper describes an experimental study on European channel shear connectors. While shear studs are widely used in steel-concrete composite elements, the channel connectors are also gaining popularity due to their certain advantages. The channel connectors do not require special equipment and standard welding procedures are adequate for attachment purposes. In addition, this type of connector offers higher amounts of shear resistance due to its high contact area with surrounding concrete. Although first studies date back to 1950s. little work has been done in the past to investigate their behavior. Majority of the work done to date was on channel connectors used in North America with a very limited parameter range. An experimental study consisting of 15 push-out tests was carried out to investigate the behavior of European type channel connectors with various heights and lengths. The ultimate resistance of the connectors obtained from experiments was compared against those predicted by North American steel design specifications. It was observed that the equations presented in American and Canadian specifications are too conservative. Based on a model that represents the typical failure mechanism in push-out tests, a new equation was developed for the ultimate resistance of channel shear connectors. It is shown that the developed equation is capable of predicting the ultimate resistance of channel connectors with reasonable accuracy. (C) 2012 Elsevier Ltd. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 5NEW TRENDS IN BASIC OXYGEN FURNACE DEPHOSPHORIZATION(Technical Faculty, Bor-serbia, 2020) Keskinkilic, E.Except for special grades of steel where it is used as an alloying element, phosphorus is regarded as an impurity that must be removed. Considering the conventional integrated iron and steelmaking, there are primarily two processes for phosphorus removal. The first is a hot metal dephosphorization (DeP) process that is applied to a blast furnace for hot metal before the steelmaking process. The second is the basic oxygen furnace steelmaking (BOS), a unique method primarily used for steelmaking, with the exception of stainless steels. Hot metal phosphorus content has a direct impact on BOS. An increase of phosphorus in hot metal is mainly related to the use of high P2O5 containing iron ores. In the current literature review, new trends of phosphorus removal in converter steelmaking are outlined. The double-slag practice was reported to be successful when hot metal P content was larger than 0.100%. It was indicated that the tapping temperature was critical for the production of low-phosphorus grades for which maximum allowable P content was 0.007% and that high tapping temperatures should be avoided. The tap-to-tap time for the double-slag process was slightly longer than the conventional converter steelmaking. It was further reported that the double-slag practice would be more economical than an establishment of a separate hot metal dephosphorization unit, if low-phosphorus grades did not have a significant share in the product mix of a steelmaking company. Endpoint phosphorus prediction was one of the important recent trends of converter steelmaking. A mixed injection of CO2-O-2 to a basic oxygen furnace was applied to enhance dephosphorization, and promising results were reported. Unfortunately, a successful process for recycling of BOS dephosphorization slag has not been reported yet.Article Citation - WoS: 7Citation - Scopus: 9Parameter Identification for an Armstrong-Frederick Hardening Law for Supercooled Austenite of Sae 52100 Steel(Elsevier, 2010) Wolff, Michael; Suhr, Bettina; Simsir, CanerThe mechanical properties of the supercooled austenite phase are sensitive parameters for the prediction of distortion of the components during heat treatments as the inelastic deformation occurs mostly on the soft austenite phase. Recent studies clarified that one of the overlooked issues related with the thermomechanical behavior of supercooled austenite during heat treatment and welding is its complicated cyclic hardening behavior (cf. Simsir et al., Acta Materialia, 2010). Based on those concerns, this article presents an optimization method for determination of temperature-dependent parameters for an Armstrong-Frederick model with combined non-linear kinematic and isotropic hardening, which can potentially pull the quality of simulations through. The results indicate that the proposed approach yields satisfactory results for simulation of heat treatments and welding even with a small and imperfect experimental data pool. (C) 2010 Elsevier B.V. All rights reserved.Article Citation - WoS: 31Citation - Scopus: 37Behavior of Steel-Concrete Partially Composite Beams With Channel Type Shear Connectors(Elsevier Sci Ltd, 2014) Baran, Eray; Topkaya, CemThis paper summarizes the findings of an experimental study investigating the flexural behavior of partially composite beams incorporating channel type shear connectors. Results from monotonic load testing of four full-scale steel-concrete composite beams and a steel beam are presented. The main effort focused on identifying the variation of strength and stiffness properties of beams with various degrees of partial composite action. Behavior of channel shear connectors in the composite beam specimens is related to those previously obtained from push-out tests of similar connectors. Finally, recommendations of the related AISC Specification on the strength and stiffness of composite beams are used for the assessment of the influence of the degree of partial composite action on flexural behavior. The experimental results revealed that even for beams with relatively low degree of partial composite action, major improvement on moment capacity and stiffness was obtained as compared to the steel specimen. The measured moment capacity of both the partially composite and fully composite beams agreed acceptably with the calculated capacities. The effective moment of inertia and the lower bound moment of inertia as specified by the AISC Specification were observed to overestimate the measured flexural stiffness of beams for all degrees of partial composite action investigated. (C) 2014 Elsevier Ltd. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 10Simulation of Through-Hardening of Sae 52100 Steel Bearings - Part I: Determination of Material Properties(Wiley-v C H verlag Gmbh, 2016) Mustak, O.; Evcil, G. E.; Simsir, C.A complete material dataset for the simulation of through-hardening of SAE 52100 (DIN/EN 100Cr6, JIS SUJ2) steel was derived by a combination of experimental and theoretical/computational methods. In the experimental part, alpha/quenching and deformation dilatometry techniques are combined with density measurements, X-Ray diffraction, optical and scanning electron microscopy to determine temperature and phase dependent transformation kinetics parameters, thermal and transformation strains, flow curves and the transformation plasticity parameter. Thermal properties such as thermal conductivity, specific heat and enthalpy and elastic properties are acquired by thermodynamics based material property calculation method using a commercial software. For most of the material properties, the results were in good agreement with the literature, while the minor discrepancies are discussed considering the raw material, equipment used, testing and evaluation procedure. In Part II of this article, compiled material data is validated successfully in an industrial oil and salt-bath quenching of bearing races.Conference Object Citation - WoS: 10Citation - Scopus: 12A Flow Stress Model for Steel in Cold Forging Process Range and the Associated Method for Parameter Identification(Springer London Ltd, 2018) Simsir, Caner; Duran, DenizDetailed thermo-mechanical characterization of DIN 16MnCr5 covering the process range of cold forging applications (0.01 s(-1) 40 s(-1), 25 A degrees C Ta 400 A degrees C) by compression tests revealed flow stress instabilities associated with dynamic strain aging (DSA) which cannot be reproduced by conventional flow stress models. As a remedy, a flow stress model capable of capturing sharp changes in flow stress, strain hardening, and strain rate sensitivity is proposed. Then, a method for parameter identification is presented which can deal with inhomogeneous deformation heating of the specimen at relatively high-strain-rate tests. The presented method involves response surface-based numerical optimization of the flawed compression tests coupled with finite element (FE) simulation. The proposed flow stress model and the extracted parameters are validated in a forward rod extrusion process without using any case-specific determined parameters in FE simulation. A natural agreement is obtained between the experimental and the predicted results in terms of both the force-displacement curve and the part geometry. The authors think that the flow stress instabilities encountered in the cold forging process range may have further consequences in other inverse analysis attempts such as friction coefficient or critical damage parameter determination and that the proper treatment of material data as put forth in this study can improve the predictive capability of process modeling.
