Papers by Keyword: Titanium Alloy

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Authors: J.R Deepak
Abstract: Nitriding is the most common surface engineering technique that is being used in Titanium alloys for improving their surface properties, viz hardness, wear resistance, etc. Ti6Al4V (Grade 5) Titanium Alloy is a super alloy that exhibits excellent mechanical strength; it is highly resistance to creep at very high temperatures which maintains good surface stability. It is resistant to corrosion and oxidation. The main objective of this review paper is to study the recent research works carried on Nitriding of Ti6Al4V alloy by using, viz gas Nitriding and laser Nitriding. This process is used in the surface hardening of machine parts such as aircraft engine parts, crank pins, valve seats, gears, bush, aero engine cylinders, aero crank shafts. Gas Nitriding is a diffusional technique in which the nitrogen atoms are diffused into the surface of the metal to obtain hard surface. By Laser Nitriding is a diffusional technique by which the surface properties of the titanium alloy is enhanced. Laser nitriding process comprises of various stages, viz, transport of heat, melting effect, diffusion and convection effect. By Nitriding technique the surface hardness of super alloys like Titanium Alloy Ti6Al4V Grade 5 can be increased by increasing the hardness on the surface there by its scope of application is widened. In this paper a literature survey is carried out and the recent research works on surface engineering of Ti6Al4V alloy using gas and laser Nitriding technique is summarized.
Authors: Kun Xian Qiu, Sheng Qin, Chun Xin Ge, Ming Chen
Abstract: Both aluminum alloy and titanium alloy have been widely used in aerospace, aviation, military and automotive industries. This research presents a study of modified drills for drilling aluminum alloy and titanium alloy. The modified drills can be expected to reduce the cutting forces and torque. A set of experiment was carried on to investigate the performance of the modified drills. A method to quantitative assess of the reduction of the thrust force and torque was given below, and the calculation shows that the modified drills can reduce the thrust force and the torque by as high as 21.16% and 90.48%, respectively, as compared to the conventional drills under the same conditions.
Authors: Koji Tsuda, Koichi Okuda, Hiroo Shizuka, Masayuki Nunobiki
Abstract: This study deals with the cutting characteristics of titanium materials when milled by a small-diameter end mill, or a micro end mill. It is well known that titanium is difficult to cut by conventional means. However, its cutting characteristics have not yet been made sufficiently clear in cases where a micro end mill less than 1 mm in diameter is used. This study chiefly involves the experimental investigation of tool wear and surface roughness of micro-end milling of Ti-6Al-4V. The findings were that tool wear did not increase much when the cutting speed was increased from 50 m/min to 200 m/min. Furthermore, the cutting force required to cut decreased at high speeds and during wet cutting. In wet cutting, the surface had a roughness (Rz) of only 0.3 μm at 200 m/min in contrast to 0.6 μm at 50 m/min.
Authors: Wei Feng He, Yu Qin Li, Xiang Fan Nie, Rui Jun Liu, Qi Peng Li
Abstract: In this paper, the microstructure and hardness of Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy with and without laser shock peening (LSP) were examined and compared. The titanium alloy samples were laser shock peened with different layers at the same power density. The microscopic structure after LSP are tested and analyzed by SEM and TEM. The results indicated that LSP changed the microstructure evidently. After 3 layers laser shock peening, there are nanocrystallization in the LSP zone. The shock wave provided high strain rate deformation and generated high-density dislocations in the material. Multiple severe plastic deformation caused by 3 to 5 LSP layers helped to rearrange the resultant dislocation, to form dislocation networks, leading to the formation of nanocrystallites. On the other hand, the microhardness across the polished surfaces of the titanium materials with and without LSP was measured. It is obvious that the laser shock peening improved the microhardness of the Ti-5Al-2Sn-2Zr-4Mo-4Cr for about 16% at the surface, and the affected depth is about 300 microns from the surface.
Authors: Dyi Cheng Chen, Ming Ren Chen, Fung Ling Nian
Abstract: In recent years, the style of 3C products demanded thin and small results due to gradual trends, though most of the industry is forming a continuous manner of stamping. However, the material thickness cannot be changed in products. This paper employs the rigid-plastic finite element (FE) DEFORMTM 3D software to investigate the plastic deformation behavior of titanium alloy (Ti-6Al-4V) workpiece for the forming processes of cellphone covers. In addition, this study utilizes the Solid Work 2010 3D graphics-rendering software for modeling, which is simulation software used to import various forming process conditions. The software analyzes the effective strain, the effective stress, critical damage value, and the die radius load distribution of the work-piece. Furthermore, this study used simulative software to analyze its forming processes for changes in grain size of the microstructure. The analytical results confirm the suitability of the current finite element software for forming processes of cellphone covers.
Authors: R.K. Sahoo, B.B. Jha, T.K. Sahoo, Barada Kanta Mishra, Olga I. Bylya, M.K. Sarangi
Abstract: Deformation of Titanium alloys close to optimal superplastic condition i.e. near superplastic regime of deformation leads to significant change in microstructures.VT-9 titanium alloy was used in order to find out those parameters of microstructure which are varying significantly during near superplastic regime of deformation. Tensile tests were carried out at 930°C up to fracture with a constant strain rate of 5*10-4 s-1 and a jump wise varying strain rate of 1*10-4 s-1 & 5*10-4 s-1 .The microstructural parameters of both air-cooled and water quenched portion i.e. size of alpha phase, percentages of alpha phase and parameter of non-uniaxiality of alpha phase were found to change significantly during near superplastic regime of deformation. It has been found that in the near superplastic regime of deformation percentage of α-phase decreased from 90% to 13%. As the β-transus temperature of this alloy is 970°C, this significant change in percentage of α-phase is attributed to deformation induced phase transformation. Optical microscopes, micro Vickers hardness test, XRD, FESEM have been used to characterize the microstructure of the material.
Authors: Sergey Demakov, Iana Semkina, Stepan Stepanov
Abstract: Samples of VT23 β-metastable titanium alloy quenched from temperatures in a range between critical and β-transus were studied in situ during heating on X-ray diffractometer. The anisotropy of orthorhombic martensite lattice was investigated. Abnormal behavior of «b» lattice spacing, which demonstrated a negative value of thermal expansion, has been revealed.
Authors: Akio Nishimoto, Kunishige Nakazawa
Abstract: The low hardness and poor tribological performance of titanium alloys restrict their wide applications in automotive fields. Nitriding is widely used to improve tribological properties, wear resistance, and corrosion resistance of steel and titanium alloys. Plasma nitriding is becoming increasingly popular because of its high nitrogen potential, short treatment time, and low environmental impact. Recently, considerable interest has been devoted to alternative nitriding methods such as active screen plasma nitriding (ASPN). In this study, a Ti-6Al-4V titanium alloy was nitrided by ASPN using a titanium double screen in order to investigate the effect of applying the double screen on the microstructure of the nitriding layer. The Ti-6Al-4V sample was placed on the sample stage in a cathodic potential. A titanium double screen was mounted on the cathodic stage around the sample stage. The sample was treated for 1-25 hours at 600oC under 200 Pa in 75% N2 + 25% H2 atmosphere. After nitriding, glow discharge optical emission spectroscopy (GD-OES) revealed that the thickness of the nitriding layer composed of TiN tended to increase with increasing the nitriding time. The Vickers microhardness of the sample surface nitrided for 25 hours reached approximately 1300 HV. Ball-on-disk wear test revealed that a wear loss of nitrided sample considerably decreased than that of untreated sample.
Authors: Zhong Bo Zhou, Jin Shan Li, Hong Chao Kou, Zhi Shou Zhu, Bin Tang, Hui Chang
Abstract: In order to develop a perspective of the new metastable β titanium alloy——TB-13, the influence of ageing treatments on the microstructure and properties has been studied. The results show that TB-13 alloy displays high age strengthening effect and fine precipitation. During the one-step aging process, the higher the aging temperature, the coarser the α plate thickness. As a result, TB-13 alloy shows the lower the strength and the higher the ductility. The best combination of strength and ductility is acquired in the TB-13 alloy after solution treatment at 1133K following aging at 813K for 16h. The ultimate strength is near 1400MPa and the specific elongation is 7.0% by ageing. At last, the details of the transformation mechanism and microstructural evolution accompanying ω-assisted α nucleation during continuous heating are discussed.
Authors: Kazutaka Sakurai, Ryuta Nakatsukasa, Mamoru Hayashi, Toshiyuki Obikawa
Abstract: This paper is related to the air jet assisted machining method for a titanium alloy, Ti-6Al-4V ELI. The air jet assisted machining method is a new machining method, in which jet of the compressed air is applied to a tool tip together with flood coolant for reducing tool wear and also for extending tool life. In this experimental study, the new method was used in high-speed end milling for confirming the effect on tool life extension. Also, the optimal position of the jet nozzle was found. It was spotted that the new method is highly effective in reducing tool wear even at a high cutting speed. It is particularly noticeable that flank wear near the corner land, which is often severely damaged, was considerably reduced by the method. It turned out that the cutting forces and the degree of surface roughness observed through this method were almost the same as those through an ordinary method with flood coolant alone.
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