A Material Perspective on Consequence of Deformation Heating During Stamping of DP Steels

Cetin, B.
Efe, Mert
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°C – 300°C due to deformation heating. Moreover, die temperature may also rise up to 100°C – 150°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°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°C – 300°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.


NUGAY, N; TINCER, T (Elsevier BV, 1994-04-01)
In this study, polyethylenes of high melt flow index LDPE and a medium melt flow index HDPE were melt blended. The mechanical, thermal properties and the thermal oxidative degradation were studied as a function of four different mixing times. The results were evaluated according to the blend composition and time of mixing. The tensile strength was found to be affected mostly by mixing time as compared with the elongation at break while the modulus remained unchanged with time of mixing. The thermal oxidativ...
Trapping center parameters in TlInS2 layered crystals by thermally stimulated current measurements
Yuksek, NS; Hasanlı, Nızamı; Ozkan, H; Karci, O (Institute of Physics, Polish Academy of Sciences, 2004-07-01)
Thermally stimulated current measurements are carried out on TlInS2 layered single crystal with the current flowing perpendicular to the c-axis in the temperature range of 10 to 90 K. The results are analyzed according to various methods, such as curve fitting, heating rate, and initial rise methods, which seem to be in good agreement with each other. Experimental evidence is found for one trapping center in TlInS2 crystal in the low-temperature region.
Deep Traps Distribution in TlInS2 Layered Crystals
IŞIK, MEHMET; Hasanlı, Nızamı; Ozkan, H. (Institute of Physics, Polish Academy of Sciences, 2009-03-01)
The trap centers and distributions in TlInS2 were studied in the temperature range of 100-300 K by using thermally stimulated currents technique. Experimental evidence was found for the presence of three trapping centers with activation energies 400, 570, and 650 meV. Their capture cross-sections were determined as 6.3 x 10(-16), 2.7 x 10(-12), and 1.8 x 10(-11) cm(2), respectively. It was concluded that in these centers retrapping is negligible as confirmed by the good agreement between the experimental re...
Analysis of Thermoluminescence Glow Peaks in beta-Irradiated TlGaSeS Crystals
IŞIK, MEHMET; YILDIRIM, TACETTİN; Gasanly, N. M. (Institute of Physics, Polish Academy of Sciences, 2016-06-01)
Thermoluminescence properties of TlGaSeS layered single crystals were investigated in the temperature range of 280-720 K. Thermoluminescence glow curve exhibited three peaks with maximum temperatures of approximate to 370, 437, and 490 K. Curve fitting, initial rise and peak shape methods were used to determine the activation energies of the trapping centers. All applied methods resulted with energies around 0.82, 0.91, and 0.99 eV. Dose dependence of the thermoluminescence intensity was also examined for t...
Modelling of non-uniform DC driven glow discharge in argon gas
Rafatov, İsmail; BILIKMEN, S. (Elsevier BV, 2007-07-16)
Physical properties of non-uniform DC-driven glow discharge in argon at pressure 1 torr are analyzed numerically. Spatially two-dimensional axial-symmetric model is based on the diffusion-drift theory of gas discharge. Results presented compare favorably with the classic theory of glow discharges and exhibit good agreement with the experimental result. Comparison with the result of spatially one-dimensional model is performed. (c) 2007 Elsevier B.V. All fights reserved.
Citation Formats
C. ŞİMŞİR, B. Cetin, M. Efe, K. Davut, and B. Bayramin, “A Material Perspective on Consequence of Deformation Heating During Stamping of DP Steels,” 2017, vol. 896, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/51656.