Papers by Keyword: High-Carbon Steel

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Authors: Tadashi Furuhara, Takuto Yamaguchi, Shoji Furimoto, Tadashi Maki
Abstract: The microstructure change by warm deformation in high-carbon steels with different initial ferrite (α) + cementite (θ) duplex microstructures has been examined. Three kinds of initial structures, i.e., pearlite, α+spheroidized θ and tempered martensite, were prepared using Fe-0.8C-2Mn and Fe-1.0C-1.4Cr alloys and compressed by 30-75% at 973K at a strain rate of 5x10-4 s-1. Equiaxed fine α grains, approximately 2μm in diameter and mostly bounded by high-angle boundaries, are formed with spheroidized θ by dynamic recrystallization during compression of the pearlite by 75%. When the (α+θ) duplex structure containing spheroidized θ was deformed, the original α grains become elongated and only subgrains are formed within them by dynamic recovery. For the tempered martensite, equiaxed α grains similar to those in the deformed pearlite were obtained after 50% compression. This indicates that the critical strain needed for the completion of dynamic recrystallization of α is smaller for the tempered martensite than for the other structures.
155
Authors: Gang Huang, Guo Hua Jiao, De Zhi Wen, Chun Quan Zhou, Kai Ming Wu
Abstract: Hot ductility of a high carbon steel 65Mn produced by CSP (Compact Strip Production) was tested on Gleeble-3500 simulator. Results show that the great reduction of hot ductility occurred between 700°C900°C. This is resulted from the formation of ferrite allotriomorphs along prior austenite grain boundaries and aluminum nitride precipitation along and near austenite grain boundaries. In order to prevent from surface cracking on thin slabs, it is suggested that the unbending temperature should be controlled above 950°C.
234
Authors: Marek Cieśla, Jerzy Herian, Grzegorz Junak
Abstract: The elements of railway turnouts made from rail sections of R260 high carbon steel must have a high resistance to abrasive and contact fatigue wear, as well as a good resistance to cracking under service loads. These mechanical properties largely determine the suitability of steel for use as railway track components. In this study, two groups of specimens were subjected to tests of mechanical properties and metallurgical analyses. The first group included material obtained from the hot-rolled block section, the rolling end temperature being Tkw = 950°C, while the second group was material after the rolling process with the subsequent 20-minute isothermal annealing at a temperature of 480°C. The microstructure of tested materials (Rm, Rp0.2, A5, Z, HB) was characterized, and their basic mechanical properties and fracture toughness in the KIc plane strain condition were determined. Also the effect of temperature, ranging from-80°C to 100°C, on the KCU impact toughness of R260 steel was established. Based on the SEM observation using the Hitachi S-3400N scanning microscope, it was found that pearlitic structure with a varied distance between cementite plates, equal to 0.29 μm and 0.09 μm, respectively, appears in the hot-rolled R260 steel and in the steel subjected to additional isothermal annealing treatment. The impact of pearlite morphology on the cracking characteristics and basic mechanical properties of materials was analyzed. It was found that at room temperature, the higher fracture toughness (KIc = 66.4 MPa·m1/2) is shown by the steel after isothermal annealing at 480°C, in which less distance between the plates of cementite has been observed in the perlite. The fracture toughness of R260 steel after hot rolling at 950°C was KIc = 48.3 MPa·m1/2. As in the case of fracture toughness, the impact strength of R260 steel after isothermal annealing was significantly greater than the impact strength of steel only after hot rolling. The determined cracking characteristics of R260 steel make it possible to determine the effect of heat treatment on the formation of microstructure and material properties, which determine the service life of rail sections.
39
Authors: János Dobránszky, Attila Magasdi, János Ginsztler
Abstract: Bandsaw blades are one of the most commonly used tools of the wood cutting industry. Their base materials are mostly unalloyed or poorly Cr-alloyed tool steels. After the review of the bandsaw blade’s cyclic load characteristics, we present the typical failures, which can be, originate in it’s cracking. With the use of these information an overall systematization has been set up by the bandsaw blade cracking types and its root causes. The main place of the failure is the weld and the heat-affected zone’s area where the welding can failure or the lack of toughness can produce cracking. An other zone, where cracking may appear is the bandsaw blade’s tooth gullet because it raises the stress intensity factor. Special material testing methods have been made to investigate the tooth gullet’s notch sensitivity from the test results that a comparison of several bandsaw blade base material, are reviewed. With the use of the results a notch sensitivity rating system has been worked out, which can be used to rate different bandsaw blade base material’s notch sensitivity.
79
Authors: Yun Li Feng, Jie Li
Abstract: Ferrite content and the plate distance of pearlite of high carbon steel wire rod are analyzed by Optical Microscope and SEM, using quantitative microstructure analysis technology. The relation between microstructure and yield strength of high carbon steel wire rods was investigated. And the mathematical model of the relation was established as: σs(Pa)=104.52×106+161.70(1-fα 1/3)S-1(m). It was validated by experiment data that the mathematical model agrees well with the experimental results.
1784
Authors: Gang Huang, Guo Hua Jiao, De Zhi Wen, Chun Quan Zhou, Kai Ming Wu
Abstract: The mechanical properties of the heat treated 65Mn steel that produced by CSP (Compact Strip Production) and conventional continuous casting process were investigated. Measured results showed that 65Mn steel produced by CSP exhibits higher hardness than that produced by conventional continuous casting process. The better mechanical property was attributed to fine-grained microstructures in the as-rolled CSP strips.
832
Authors: George Krauss, David K. Matlock, A. Reguly
835
Authors: Kyoo Young Lee, Young Roc Im, Leo Kestens, Gyo Sung Kim
Abstract: The microstructural evolution and the softening behavior of hot rolled and 60% cold rolled 0.85wt% carbon pearlitic steels during spheroidization annealing have been investigated by using the textural and microstructural information contained in the Orientation Imaging Microscopy (OIM) scans. The local boundary energy map, recently suggested by the present authors, is used to monitor the changes of stored plastic strain energy distribution in ferrite during the annealing process, which shows that the spheroidization process of cementite is finished before the completion of recrystallization of the 60% cold-rolled high carbon pearlitic steel.
4556
Authors: M.A. Martinez, R. Calabrés, J. Abenojar, Francisco Velasco
Abstract: In this work, ultrahigh carbon steels (UHCS) obtained by powder metallurgy with CIP and argon sintered at 1150°C. Then, they were rolled at 850 °C with a reduction of 40 %. Finally, steels were quenched at 850 and 1000 °C in oil. In each step, hardness, bending strength and wear performance were evaluated. Obtained results are justified with a metallographic study by SEM. Both mechanical properties and wear resistance are highly favoured with the thermomechanical treatment that removes the porosity of the material. Moreover, final quenching highly hardens the material. The obtained material could be used as matrix for tool steels.
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