Nalbant, Muammer | Altın, Abdullah | Gökkaya, Hasan

Article | 2007 | Materials and Design28 ( 4 ) , pp.1334 - 1338

The effects of cutting speed and cutting tool geometry on cutting forces are investigated in this study. For this purpose, nickel-base super alloy, Inconel 718, is machined with dry cutting conditions by using digital controlled computer lathe with ceramic cutting tools in two different geometries and three different material qualities. Metal removing process is carried out for four different cutting speeds (150 m/min, 200 m/min, 250 m/min, and 300 m/min), while a cutting depth of 2 mm and a feed rate of 0.20 mm/rev are kept constant. As a result of the experiments, the lowest main cutting force, which depends on tool geometry, is o . . .btained as 672 N with KYON 2100 SNGN 120712 ceramic tool and the maximum cutting force is determined as 1346 N with the ceramic cutting tool having KYON 4300 RNGN 120700 geometry. Depending on the cutting speed, the lowest main cutting force is recorded as 812 N at 250 m/min while the highest main cutting force is recorded as 955 N at 150 m/min. Plastic deformation, flank edge wear, notch and build-up edge are determined in high cutting speeds. © 2006 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Acarer M. | Gülenç B. | Findik F.

Article | 2003 | Materials and Design24 ( 8 ) , pp.659 - 664

The aim of this study was to investigate the strength of explosive welded metals with the same chemical compositions. Different welding interfaces (straight, wavy and continuous solidified-melted) were used with changing explosive welding parameters [stand-off distance ( s ), explosive loading ( R ) and anvils]. Joined metals were investigated under heat-treated and untreated conditions. Results on the microstructure, microhardness, tensile shear strength and bending tests are reported. According to the experimental results, the effect of the anvil on the explosive welding process was only the joining or not-joining performance. It . . .was shown that the bonding interface changed from a straight to a wavy structure when the explosive loading and stand-off distance were increased. For wavy interfaces, when the explosive loading was increased the wavy length and amplitude increased. Results of tensile shear and bending tests showed that heat-treated specimens have more strength than untreated samples. According to tensile shear test results, straight and wavy interfaces had similar strength. In addition, in bending tests of untreated specimens it was shown that the bending zone had some cracks. © 2003 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Gündüz S. | Cochrane R.C.

Article | 2005 | Materials and Design26 ( 6 ) , pp.486 - 492

In the present work precipitate distributions in a C-Mn-Al-V-N microalloyed steel and hardness were examined for as-received, heat-treated and heat-treated & tempered samples. Examination of as-received and heat-treated samples from the vanadium microalloyed steels using transmission electron microscopy revealed quite different precipitate distributions. The type and sizes of the precipitate particles and also hardness of the steel samples were markedly affected as the austenitisation time and cooling rates were changed. Tempering steel samples after air cooling produced fine matrix precipitates which are closely spaced, obstruct mo . . .ving dislocations and hence make the steel harder. © 2004 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Nalbant, Muammer | Altın, Abdullah | Gökkaya, Hasan

Article | 2007 | Materials and Design28 ( 5 ) , pp.1719 - 1724

In this study, the effects of cutting tool coating material and cutting speed on cutting forces and surface roughness are investigated. For this purpose, nickel based super alloy Inconel 718 is machined at dry cutting conditions with three different cemented carbide tools in CNC lathe. Metal removing process is carried out for five different cutting speeds (15, 30, 45, 60, 75 m/min.) while 2 mm depth of cut and 0.20 mm/rev feed rate are to be constant. Main cutting force, Fc is considered to be cutting force as a criterion. In the experiments, depending on the tool coating material, lowest main cutting force is found to be 506 N at . . .75 m/min with multicoated cemented carbide insert whose top layer is coated by Al2O3. Lowest average surface roughness (0.806 µm) is obtained at the cutting speed of 15 m/min with single coated (TiN) cemented carbide inserts. © 2006 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Korkut I. | Boy M. | Karacan I. | Seker U.

Article | 2007 | Materials and Design28 ( 8 ) , pp.2329 - 2335

In this study, measurement of the chip-back temperature developed during cutting was investigated using an embedded thermocouple into the cutting tool. AISI 1117 steel was used as the workpiece material and a K type thermocouple was used for the temperature measurement. The cutting tool used was uncoated and without chip braker and in the form of SCMW 12 M508-S2F according to ISO 1832. This cutting tool was fixed on a tool holder in the form of SSBCR 25 25 M12 and the side cutting edge angle during tests was 75° as suggested in ISO 3685. The cutting tests were carried out on a Johnford TC35 CNC turning center. In selecting the cutti . . .ng parameters, the reference values indicated in ISO 3685 were used. In order to locate the thermocouple on the cutting tool, a Flir Systems Therma Cam thermal camera was used. The results showed that increasing cutting speed, feed rate and depth of cut resulted in increase in the temperature at the back rake surface. However, cutting speed had the most influence on the temperature. © 2006 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Yaşar M. | Korkmaz Z. | Gavas M.

Article | 2007 | Materials and Design28 ( 10 ) , pp.2647 - 2653

Multi-point deep drawing (MPDD) is an advanced manufacturing technology for 3D sheet metal parts and it can form a variety of part shapes without the need for solid dies. In this study, a test set has been prepared for multi-point deep drawing process utilizing the multi-point forming technology. Drawability attributes of gradually rectangular shaped container have been observed using a sheet, which has the quality of Erdemir 7114 and is suitable for deep drawing process, and also using multi-pointed punch with a given tool geometry and a draw velocity. The blank shape to be drawn without wrinkling and tearing has been determined. W . . .rinkles and dimples are the major forming defects in the MPDD process. In conventional deep drawing, the method to form sheet metal with a blank holder is an effective way to suppress wrinkling; and the same is true in MPDD. The process of multi-point forming technology decreases production cost of die, provides flexible usage, and it is convenient to achieve the most even deformation distribution. © 2006 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Altan M.F. | Kartal M.E.

Article | 2009 | Materials and Design30 ( 6 ) , pp.2243 - 2249

This paper deals with change of buckling coefficients of symmetrically laminated reinforced concrete plates with a central rectangular hole under biaxial static compression loadings using finite element method. Composite structure of these plates has been constituted from four, six, eight and ten laminas including steel and concrete. The effect of change in central rectangular hole from the point view of size and direction on buckling coefficients is investigated in this study. Symmetrically laminated plates under biaxial in-plane loadings are taken into consideration in the analyses for simply supported and clamped boundary conditi . . .ons. Obtained results are compared with each other according to a/L and b/L where a, b are the hole sizes and L is the length of the plate, respectively. Crown Copyright © 2008 Daha fazlası Daha az

Kaçar R.

Article | 2004 | Materials and Design25 ( 1 ) , pp.1 - 9

The evolution rate of hydrogen from a duplex weld depends on sample geometry, temperature and microstructure. These factors have important consequences for the determination of hydrogen in duplex stainless steel welds. Because of the low hydrogen diffusibility and high hydrogen solubility in austenite, a standard method (BS 6693: 1988) which existed to determine the hydrogen content of ferritic steel welds as a means of assessing welding consumables, is not suitable for duplex welds. As a result of extensive research, a modified test method has been used involving encapsulation of the weld sample in Pyrex, evolution at 400 °C for 24 . . . h, and followed by hydrogen analysis in an Oerlikon/Yanaco gas chromatograph. In this present work, the effect of solidification mode and microstructure on weld hydrogen content, and the evolution of hydrogen from such welds has been investigated by using experimental electrodes which are designed to give varying ferrite/austenite ratio in the welds. It was found that the measured weld hydrogen contents were almost constant since they arose from the flux/binder combinations which were the same for each type of experimental electrodes. Thus, the potential hydrogen from each type was the same and similar amounts became trapped during the rapid solidification of the weld pool, irrespective of final ferrite content. © 2003 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Karabulut H. | Gündüz S.

Article | 2004 | Materials and Design25 ( 6 ) , pp.521 - 527

In the present study, the tensile properties of three microalloyed medium carbon steels, containing different amount of vanadium, were investigated in the temperature range of 25-400 °C at a strain rate of 1.2 × 10-3s-1. Both microstructure and fracture surfaces were examined using optical and scanning electron microscopic (SEM) techniques. The three steels displayed different tensile behavior at elevated temperatures and these differences are discussed with regard to the chemical compositions and fracture surface morphology. © 2004 Elsevier Ltd. All rights reserved.

Kaçar R. | Kökemli K.

Article | 2005 | Materials and Design26 ( 6 ) , pp.508 - 516

Due to their higher welding speed, automation and weld pool protection against to the atmosphere gases, gas metal arc welding (GMAW) process is widely used in industry. Due to the less stable arc associated with the use of consumable electrodes, GMAW process is not clean as good as gas tungsten arc welding process. Furthermore, the greater arc length in GMAW process also reduces the protective effect of the shielding gas. Due to electrochemical and thermochemical reactions between weld pool and arc atmosphere, it is quite important, especially weld metal toughness and joining of reactive materials to entirely create inert atmosphere . . . for GMAW process. Therefore, a controlled atmosphere cabinet was developed for GMAW process. Low carbon steel combinations were welded with classical GMAW process in argon atmosphere as well as controlled atmosphere cabinet by using similar welding parameters. The mechanical and metallurgical properties of both weldments were evaluated. Result shows that toughness of the weld metal that was obtained in the controlled atmosphere cabinet much higher than that of classical GMAW process. The metallographic examination also clarified that there was not any gas porosity and inclusion in the weld metal compared with classical process. © 2004 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Kaçar R. | Baylan O.

Article | 2004 | Materials and Design25 ( 4 ) , pp.317 - 329

The metallurgical characteristics, tensile, hardness, toughness and corrosion resistance of dissimilar welds between X5CrNi18-10 grade austenitic and X20CrMo13 grade martensitic stainless steel have been evaluated. Both austenitic and duplex stainless steel electrodes were used to join this combination, using multipass manual metal arc welding process. Defect free welds were made with each welding consumable. It was found that the tensile strength of weldment, which was produced by duplex electrode (E2209-17), was slightly lower than that of austenitic electrode (E308L-16). The toughness of the both E2209-17 and E308L-16 deposits wa . . .s acceptable even at low temperature regardless of heat input. Hardness was increased in both welds made with E2209-17 duplex and E308L-16 austenitic electrode along the X20CrMo13/weld metal fusion boundary due to heat annealing and then following high cooling rate. The pitting corrosion resistance of the weld metal made with E308L-16 and E2209-17 filler metal was found acceptable. Although, heat affected zone in the weldment and X20CrMo13 base metal were affected by electrolytic corrosion. This investigation has shown that both filler metals can be used to join austenitic stainless steel to the martensitic stainless steel. © 2003 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Cetinkaya K.

Article | 2007 | Materials and Design28 ( 1 ) , pp.362 - 367

Over the years, significant improvements have been made in the area of press feeding system. As feeds become more accurate, faster, and varied in their use, the entire system must also be more capable to accommodate these new requirements. Generally, mechanical feeders used for thin sheet metal strips are adjusted to press eccentric shafts. Pneumatic feeders are installed to an air pressure system. Both mechanical and pneumatic feeders have been used in industry. These systems had many overlapping applications. Therefore, it is important for the industry to understand both processes, in order to optimize the process. The comprehensi . . .ve knowledge on usefulness, deformation and damage scratches would help the users to judge which feeder is more appropriate for each type of application. This paper presents how to select a useful feeder according to deformation and damage scratches of both mechanical and pneumatic system. Case on feeding dead-soft material, cold-rolled material and hot-rolled material of different thicknesses are also discussed in a comparison study. © 2005 Elsevier Ltd. All rights reserved Daha fazlası Daha az