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Conference Object Citation - WoS: 4Citation - Scopus: 4A Material Perspective on Consequence of Deformation Heating During Stamping of Dp Steels(Iop Publishing Ltd, 2017) Simsir, C.; Cetin, B.; Efe, M.; Davut, K.; Bayramin, B.Recent studies showed that, during stamping of high strength steels at industrially relevant production rates, local temperature in the blank may rise up to 200 degrees C - 300 degrees C due to deformation heating. Moreover, die temperature may also rise up to 100 degrees C - 150 degrees C for progressive stamping dies. Based on the common assumption that the blank softens as the temperature increases, thermal softening creates a margin in Forming Limit Diagram (FLD) and therefore the FLD determined at room temperature can safely be used for those cases. In this article, the validity of this assumption on DP590 steel is questioned by high temperature tensile tests (RT - 300 degrees C) at various strain rates (10(-3) s(-1) - 1 s(-1)). The results indicated a decrease both in uniform and total elongation in 200 degrees C - 300 degrees C range together with several other symptoms of Dynamic Strain Aging (DSA) at all strain rates. Concurrent with the DSA, the simulated FLD confirms the lower formability at high temperature and strain rates. Thus, it is concluded FLD determined at RT may not be valid for the investigated steels.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: 17Citation - Scopus: 26Process-Chain Simulation for Prediction of the Distortion of Case-Hardened Gear Blanks(Wiley-v C H verlag Gmbh, 2012) Simsir, C.; Hunkel, M.; Luetjens, J.; Rentsch, R.In this study, a process-chain simulation model is presented for the prediction of distortion of low-pressure gas carburised SAE 5120 (EN 20MnCr5) steel gear blanks. For this purpose, the evolution of the banded microstructure stemming from the continuous casting process was traced by computer simulations of subsequent shape rolling, forging and machining steps. Then, the simulated local orientation angles of the deformed banded microstructure are transferred to heat treatment simulation module as an input for the recently developed material model that exploits the Anisotropic Transformation Strain (ATS) concept to reproduce the dishing behaviour which cannot be reproduced by former models. The results indicate that the suggested procedure provides quite good predictions of the dishing directions and dishing-free cutting strategy, whereas; the dishing magnitude is predicted fairly reasonably considering large scatters in the experiments.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.
