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    Assessment of Conical Die Deep Drawability of DP800 and MART1400 Advanced High Strength Steels
    (Society of Automotive Engineers Turkey, 2023) Şen, N.; Civek, T.; Tongü, E.
    Deep drawing is one of the most important and vastly conducted sheet metal forming method. Thus, even small improvements achieved on the deep drawability of sheet metals significantly increases the ability of sheet metal to be formed into more complex products. Advanced high strength steels (AHSSs) are one of the most popular steels in the automotive industry due to their high strengths. However, their low ductility causes considerable splitting problems near the cup punch region. In this study, deep drawing experiments have been conducted in conical dies with four different angles (0°, 7.5°, 12.5°, and 20°) for DP800 and MART 1400 steels to observe whether a higher deep drawing ratio (DDR) can be achieved by deep drawing in conical dies for AHSSs. In addition, finite element analysis (FEA) has been utilized to estimate the DDR for each types of steels in different conical die setups. It has been observed that the deep drawability of MART1400 steel has not improved in any of the conical die setups. However, DDR of DP800 has slightly increased by 2.46% by deep drawing with 20° die angle. A good agreement with the numerical and experimental results has been achieved. © 2023 Universidade do Vale do Rio dos Sinos. All rights reserved.
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    INVESTIGATION OF THE FLOW BEHAVIOUR OF MARTENSITIC STEELAT ELEVATED TEMPERATURES VIA UNIAxIAL TENSILE TESTS
    (Polska Akad Nauk, Polish Acad Sciences, Inst Metall & Mater Sci Pas, 2025) Sen, N.; Civek, T.; Elkoca, O.; Cevik, E. c
    In recent years, advanced high strength steels have been the main choice of automobile manufacturers due to their excellent strengths and decent formability. In this study, the forming behaviour of a martensitic steel (MART 1200) at elevated temperatures, where higher formability and an acceptable strength can be achieved, has been investigated. For this purpose, tensile test experiments have been conducted at room temperature, 175 degrees C, 275 degrees C, 375 degrees C and 475 degrees C in two different strain rates (0.005 s-1, 0.05 s-1). The flow behaviour, elongation capacity, strain rate sensitivity, strain hardening and strain hardening rate of MART1200 have been investigated and fracture surfaces and microstructures have been examined by scanning electron microscope. It has been shown that the strain rate sensitivity of MART1200 increases significantly after 275 degrees C and, for the higher strain rate, a significant improvement up to 80% in the elongation capacity has been achieved in return for a 19% strength reduction at 375 degrees C.