Face milling of nickel-based superalloys with coated and uncoated carbide tools

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Production of functionally graded AlB2/Al-4%Mg composite by centrifugal casting

In this study, production of functionally graded AlB2 reinforced Al-4%Mg composite has been investigated. In-situ high-aspect-ratio flake AlB2 reinforcement was obtained by the addition of boron oxide to the liquid Al-Mg at 1400 °C. It has been observed that there were two distinct regions without a smooth grading: one is rich of and the other is poor of AlB2. The results showed that the highest AlB2 content has been found to be around 10% in external zones, whereas the lowest AlB2 content has been observed to be 0.02% in the internal zones.  Additionally,   results showed that, depending on the increase in the reinforcement phase in external zones, up to 20 % increase in the hardness of the composite has been achieved

APPLICATION OF TAGUCHI METHOD TO INVESTIGATE THE EFFECT OF SOME FACTORS ON IN-SITU FORMED FLAKE STRUCTURES OF AL/ALB2

A new in-situ metal matrix composite has been produced by liquid state reaction between aluminium and boron. The common boride phases obtained from this reaction are AlB12 and AlB2 of which the latter is stable at room temperature. One of the critical parameters of the reinforcement is the aspect ratio of AlB2 flakes. In this study, the Taguchi design method has been employed to examine the effects of three process parameters of additive elements to Al matrix, cooling rate in the AlB2 (solid) + Al(liquid) region, and cooling regime in the AlB2(solid) + Al (liquid) region on the size of AlB2 flakes. In the experiments, melting, casting, solidification, metallographic techniques, optical microscope, SEM and wet analysis techniques have been used. Results showed that 1.3 wt % boron has been dissolved in the aluminium at 1400 °C by adding boron oxide (B2O3) resulting in AlB2 flakes of 2.5 % by volume. It is also concluded that the AlB12(solid) + Al (liquid) region has to be passed with adequately high cooling rates in order to obtain AlB2 flakes with highest possible aspect ratios

Tool life performance of multilayer hard coatings produced by HTCVD for machining of nodular cast iron

In this study, tool life performance of multilayer hard coatings was evaluated for machining of nodular cast iron. With this regard, TiCN+TiC+TiCN+Al2O3+TiN and TiCN+TiC+TiCN+Al2O3+TiN multilayered coatings with different thicknesses were fabricated on WC substrates using high temperature chemical vapor deposition (HTCVD). These cutting tools with hard multilayered coating systems were used in longitudinal turning of nodular cast iron under cutting condition encountered in the shop floor. To investigate the tool life performance in cutting tools coated by HTCVD method, cutting experiments were performed in CNC turning bench by using three distinct cutting tools having multilayered hard coatings and WC insert with square edges, and two types of nodular cast irons. Cutting speed, depth of cutting, and feed rate were kept as constant values. Tool life based on flank wear was the parameters considered to compare the three cutting tools. It was found that TiCN+TiC+TiCN+Al2O3+TiN (T3) multilayer coating with 10.5 mu m thick exhibited better performance according to all parameters. (C) 2008 Elsevier Ltd. All rights reserved

INVESTIGATION OF UNLUBRICATED SLIDING WEAR BEHAVIOURS OF IN-SITU AlB2/Al METAL MATRIX COMPOSITE

SAVAS, Omer/0000-0001-7454-1457WOS: 000298455600004In this study, wear behaviour of AlB2/Al composite materials produced through in-situ method have been experimentally investigated. Four different composite materials that include 5wt.%, 10wt.%, 20wt.% and 30wt.% AlB2 reinforcement phase were tested using pin-on-disk arrangement. The effects of the rate of reinforcement on wear and friction behaviours have been investigated. Wear tests are carried out at 1.83, 3.40 and 4.71 m/s sliding speeds under 10, 20 and 40 N applied loads. The test results show that wear rate increases with the increase in applied load and sliding distance. Increasing the rate of reinforcement phase in the matrix has proportionally increased the wear resistance by 3% to 30%. Hence the greatest wear resistance has been observed with the composite materials having 30wt. % AlB2 reinforcement. Analysis of the worn surfaces of composite samples shows that abrasive and adhesive wear mechanisms are more effective.Turkish Science Council (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [107M023]The authors would like to thank the Turkish Science Council (TUBITAK) for financial support through project number: 107M023

Effect of cutting speed on the performance of coated and uncoated cutting tools in turning nodular cast iron

This paper presents the results of an experimental investigation on the effect of cutting speed in turning nodular cast iron with coated and uncoated cutting tools. Three different carbide cutting tools were used, namely TiCN + TiC + TiCN + Al2O3 + TiN-coated carbide tools with multilayer coating of 7.5 and 10.5 trn thickness and uncoated WC/Co tool. Tbrning experiments were carried out at four different cutting speeds, which were 125, 150, 175 and 200 m/min. Feed rate (f) and depth of cut (a(p)) were kept fixed at 0.25 mm/rev and 1.5, respectively, throughout the experiments. Tool performance was evaluated with respect to tool wear, surface finish produced and cutting forces generated during turning. Uncoated WC/Co tool was the worst performing tool with respect to tool wear and was the worst with respect to surface finish. If tool wear, surface finish and cutting force results are considered together, among the three tools studied, 10.5 mu m thick multilayer TiCN + TiC +TiCN + Al2O3 + TiN-coated carbide tool with external TiN layer is the most suitable one for turning nodular cast iron, especially at high cutting speeds. (c) 2007 Elsevier B.V. All rights reserved