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    An Experimental and Statistical Evaluation of The Cutting Parameters on The Machinability of Hadfield Steel
    (Gazi Univ, 2016) Kivak, Turgay; Uzun, Gultekin; Ekici, Ergun
    The effects of cutting tool coatings and cutting parameters (cutting speed, feed rate) on the cutting forces and surface roughness during the turning of Hadfield steel were investigated in this study. Cutting experiments were made on a CNC lathe under dry cutting conditions by employing CVD TiCN/Al2O3/TiN-, PVD TiAlN- and PVD TiAlN/AlCrO-coated cementite carbide inserts. Four different cutting speeds (100, 140, 180, 220 m/min), two different feed rates (0.2, 0.3 mm/rev) and a constant cutting depth of 0.8 mm were used as the cutting parameters. At the end of the tests, cutting force and surface roughness results were subjected to variance (ANOVA) and multiple regression analyses. The experimental results showed that the PVD TiAlN coating was superior to the CVD TiCN/Al2O3/TiN and PVD TiAlN/AlCrO coatings with respect to cutting force and surface roughness. The correlation coefficients of the statistical model developed at the end of the analysis were R-2=0.994 and R-2=0.996 for the cutting forces and surface roughness, respectively. The feed rate was found to be the most effective parameter on the cutting forces and surface roughness, with contribution ratios of 91.31% and 94.79% respectively.
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    Öğe
    Effects of Deep Cryogenic Treatment on the Wear Resistance and Mechanical Properties of AISI H13 Hot-Work Tool Steel
    (Springer, 2015) Cicek, Adem; Kara, Fuat; Kivak, Turgay; Ekici, Ergun; Uygur, Ilyas
    In this study, a number of wear and tensile tests were performed to elucidate the effects of deep cryogenic treatment on the wear behavior and mechanical properties (hardness and tensile strength) of AISI H13 tool steel. In accordance with this purpose, three different heat treatments (conventional heat treatment (CHT), deep cryogenic treatment (DCT), and deep cryogenic treatment and tempering (DCTT)) were applied to tool steel samples. DCT and DCTT samples were held in nitrogen gas at -145 degrees C for 24 h. Wear tests were conducted on a dry pin-on-disk device using two loads of 60 and 80 N, two sliding velocities of 0.8 and 1 m/s, and a wear distance of 1000 m. All test results showed that DCT improved the adhesive wear resistance and mechanical properties of AISI H13 steel. The formation of small-sized and uniformly distributed carbide particles and the transformation of retained austenite to martensite played an important role in the improvements in the wear resistance and mechanical properties. After cleavage fracture, the surfaces of all samples were characterized by the cracking of primary carbides, while the DCT and DCTT samples displayed microvoid formation by decohesion of the fine carbides precipitated during the cryo-tempering process.
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    Öğe
    Evaluation of machinability of hardened and cryo-treated AISI H13 hot work tool steel with ceramic inserts
    (Elsevier Sci Ltd, 2013) Cicek, Adem; Kara, Fuat; Kivak, Turgay; Ekici, Ergun
    The positive effects of deep cryogenic treatment on the wear resistance of cutting tools and workpiece material are well known; however, no information has been reported about the effect on the machinability of cryo-treated tool steel in hard turning. In order to investigate the effects of cryogenic treatment on the machinability of hardened and cryo-treated tool steel, a number of investigations were performed on the hard turning of cryo-treated AISI H13 hot-work tool steel with two ceramic inserts under both dry and wet cutting conditions. Three categories of the hot-work tool steel were turned in the machinability studies: conventional heat treated (CHT), cryo-treated (CT) and cryo-treated and tempered (m). Experimental results showed that the lowest wear and surface roughness (Ra) values were obtained in the turning of the CTT samples. Additionally, in terms of main cutting force (Fc), surface roughness (Ra) and tool wear, Ti[C, N]-mixed alumina inserts (CC650) showed a better performance than SiC whisker-reinforced alumina inserts (CC670) under both dry and wet cutting conditions. The use of cutting fluid slightly improved the machinability of the tool steel. (C) 2013 Elsevier Ltd. All rights reserved.