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    Effects of Blanking Speed on the Shear Surface of Mild Steel (St37)
    (Polish Acad Sciences Inst Physics, 2016) Kanca, E.; Eyercioglu, O.; Karahan, I. H.; Gunen, A.; Gov, K.
    Blanking operation is widely used to cut sheet or plates by a shearing process between punch and die. The process of shearing and the conditions of the sheared surface are influenced by the punch, the die, the speed of punching, the clearance between the punch and the die. In this study, effects of high speed blanking on surface quality and corrosion properties of mild steel St37 shear surface have been investigated. The work presented in this paper aims at evaluating the shear surface quality improvements of the St37 resulting from the use of high energy rate forging machine. The appraisal is based on criteria related to surface accuracy and corrosion resistance characterization. For this purpose, St37 mild steels were cut using three different punch speeds hydraulic presses at nearly quasistatic, conventional mechanical presses at low punch velocity (0.2 m/s) and high energy rate forging machine at high punch velocity (10 m/s), for different die clearances (4.5%-6% of sheet thickness). After accelerated corrosion tests, blanks were performed in conjunction with scanning electron microscopy technique to study the cutting process of the blanks at room temperature. In fact, by using high energy rate forging machine, a reduction of more than 25% of the surface roughness (R-a) was realized and better resistance to stress corrosion cracking and pitting corrosion was noticed. It was observed that the corrosion resistance of the high energy rate forging-cut specimen was better than that of the hydraulic-cut and mechanical-cut specimens.
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    FRICTION AND WEAR BEHAVIOUR OF BORIDED AISI 304 STAINLESS STEEL WITH NANO PARTICLE AND MICRO PARTICLE SIZE OF BORIDING AGENTS
    (Scibulcom Ltd, 2014) Gunen, A.; Ulutan, M.; Gok, M. S.; Kurt, B.; Orhan, N.
    In this study, AISI 304 stainless steel was subjected to solid bonding treatment with 10-50 nm particle size Nanoboron and commercially EKabor 3 powders. Processes were carried out at temperatures of 1223 and 1273 K for 2 and 4 h of treatment. Friction and wear behaviour of the samples bonded with different sizes of bonding agents has been examined. Wear experiments were performed by reciprocating a sliding wear test at dry conditions. After the wear tests, wear track area, wear track volume and wear rate were calculated based on the surface of the worn materials. The samples bonded with EKabor 3 and Nanoboron powder showed 5 and 8 times higher wear resistance than non-bonded AISI 304 stainless steel, respectively. Bonded steel samples were characterised by optical microscopy, scanning electron microscopy (SEM), microhardness and X-ray diffraction analyses (XRD). Metallographic studies showed that the boride layers have a flat and smooth morphology both in the AISI 304 steel and the boron powder. The thickness and hardness of the boride layer measured between the ranges of 23-33 mu m in thickness, 1020-1264 HV0.01 for EKabor 3 and 49-67 mu m, 1880-2200 HV0.01 for boron nano-particles, depend on the bonding time and temperature.
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    Friction and wear behaviour of borided AISI 304 stainless steel with nano particle and micro particle size of boriding agents
    (Scibulcom Ltd., 2014) Gunen, A.; Ulutan, M.; Gok, M.S.; Kurt, B.; Orhan, N.
    In this study, AISI 304 stainless steel was subjected to solid boriding treatmentwith 10-50 nm particle size Nanoboron and commercially EKabor 3 powders.Processes were carried out at temperatures of 1223 and 1273 K for 2 and 4 hof treatment. Friction and wear behaviour of the samples borided with differentsizes of boriding agents has been examined. Wear experiments were performedby reciprocating a sliding wear test at dry conditions. After the wear tests, weartrack area, wear track volume and wear rate were calculated based on the surfaceof the worn materials. The samples borided with EKabor 3 and Nanoboronpowder showed 5 and 8 times higher wear resistance than non-borided AISI 304stainless steel, respectively. Borided steel samples were characterised by opticalmicroscopy, scanning electron microscopy (SEM), microhardness and X-ray diffractionanalyses (XRD). Metallographic studies showed that the boride layershave a flat and smooth morphology both in the AISI 304 steel and the boronpowder. The thickness and hardness of the boride layer measured between theranges of 23-33 ?m in thickness, 1020-1264 HV0.01 for EKabor 3 and 49-67 ?m,1880-2200 HV0.01 for boron nano-particles, depend on the boriding time and temperature.