Advanced Materials Research Vols. 984-985

Abstract: A 7150 Al-Zn-Mg-Cu alloy is artificially aged at 120 ^oC for varying time. The peak hardness (T6 temper) is obtained at about 24 h at that temperature. Further, the T6 temper is subjected to retrogression and reageing (RRA) treatment. Slow strain rate test (SSRT) has been carried out on the T6 and RRA tempers. SSRT results indicated that the RRA temper have higher resistance to SCC compared to that of T6 temper. SCC behaviour of the alloy tempers have been explained with the help of microstructural features studied by transmission electron microscope (TEM). The large, discrete and discontinuous grain boundary precipitates observed in the microstructure of the RRA temper are believed to be the responsible factor for achieving higher SCC resistance. Further, SEM fractographs and crack morphology have also been analyzed to evaluate the SCC behaviour of the alloy tempers.

Abstract: Aerospace industry and automobile industries are enhanced performance necessary for materials with better qualities compare to conservative materials. In automotive areas, this is predominantly factual for power train employed as conflicting to body application. For each kind of appliance, description such as hardness of the material, wear resistance, temperature withstands ability, plasticity, fracture, fatigue strength, etc. It must be as high as possible, while parameters such as density and cost must be minimized; the latter is of general concern for automobile use and relatively inexpensive light aircraft. Because of their low density, the light metals based on aluminum, magnesium, and titanium are particularly attractive for both types of applications. In this paper, advanced material of Al6061/SiC/Al₂O₃ hybrid composites is discussed, followed by a consideration of advanced material specifically in aerospace and automotive applications. Processing the lightweight metal, with enhanced hardness properties is presented.

Abstract: Al7075alloy and Al₂O₃ powders were synthesized via high-energy ball mill for 5 h. Al7075alloy powders were mixed with Al₂O₃ ranging from 5 to 15 vol. %, compacted by cold uniaxial compaction at 400 MPa. The green pellets were degassed at 350 oC for 30 min, and then sintered in the temperature of 600 oC under argon atmosphere for 120 min. It was shown that better density, vickers micro hardness and corrosion resistance were achieved up to 10 vol. % due to uniform distribution of Al₂O₃ particles throughout matrix. Beyond 10 vol. %, Al₂O₃ resulted in clustering, porosity and poor interfacial bonding and their properties.

Abstract: Metal to the metal wear analysis of Aluminium (Al6061grade) alloy, dis-continuously reinforced with ceramic particles of SiC and Al₂O₃ deliver this paper. The Al matrix with 5 to 25% of vol. Fractions of SiC and Al₂O₃ particulate reinforcements were formed in Hybrid Metal Matrix Composite (HMMC) by stirring casting technology. They are finding applications in automotive, aeronautical and sport goods. For the proper use of these composites, its mechanical properties and wear properties are to be evaluated. The dry sliding behavior of these SiC and Al₂O₃ particulates HMMCs and that of Al alloy at atmosphere was analyzed with a pin on disc type wear testing machine. The result indicates that, the scanning electron micrographs of the worn surfaces of the hybrid composites show the worn surface of the composite alloy is rougher than the unreinforced Al6061alloy.

Abstract: -Al7075 T6 alloys are widely used in the aircraft, automotive and die and mold making industry, yet at any time aluminium components should be designed with a third body or in an harsh environment they must be protected with an overlying coating inorder to increase their useful lifespan and improve their surface performance especially in wear and corrosion. The most wide spread technique used to modify the surface properties of Al7075 T6 among them one of the most promosing technology is plasma spraying. It is widely used to manufacture anti-wear and anti-corrosion coatings on to a large class of bulk materials. Extreme performance and high flexibility are the Main characteristic of the coatings achievable by Plasma Spray process. In this work Nickel Carbide + Chromium Composite coating was successfully prepared and deposied with various thicknesses on the Aluminium alloy surface. Nickel Carbide + Chromium composite coating exhibits a significantly increased wear resistance property in the material. The result obtained in this work indicated that the plasma spraying method will be the promising process to coat the composite coating on aluminium based alloy.Keywords: Al 7075 T6, Plasma Spray Process, Nickel Carbide + Chromium

Abstract: The main focus of this work is to study and evaluate the corrosion behavior of aluminium alloy 7075 under slightly varying temperature conditions. The corrosion behavior was found out using the Salt Mist test. Aluminium alloy 7075 possesses better corrosion resistance, so it is important to foresee the corrosion behavior of this alloy for varied applications. The Corrosion Penetration Rate was evaluated for the small temperature changes and the results show that the penetration rate increases as temperature increases gradually along with the time for which the specimens are tested. The final result is that aluminium alloy 7075 follows logarithmic law of corrosion at low temperatures.

Abstract: In this study, the relationship between vibration and tool wear and also influence of sensor positioning in tool codition monitoring were investigated during drilling. For this purpose, a series of experiment were conducted in a CNC vertical milling machine using drilling cycle. A 6 mm diameter HSS drill and EN24 as workpiece material were used in these experiments. The vibration was measured in the transverse direction of sensor which is positioned on the workpiece with constant distance from the holes to be drilled for monitoring tool wear as in previous studies. But, positioning of sensor in a constant place with equal distance from all holes to be drilled is not possible for all the workpiece profiles in actual practice. Experiments show that the distance of sensor from the holes in drilling affects the vibration signals for the same state of wear.It shows that the tool wear models presented in previous studies using acceleration signals are sensor location dependent. This work presents a Variance-amplitude of the vibration signals received for tool condition monitoring which is the most sensitive statistical parameter than other statistical parameters such as Root Mean Square (RMS), Exponential, Peak, max-min, mean and standard deviation. Results showed that there was no considerable increase in the vibration amplitude of variance until flank wear value of 0.30 mm was reached, above which the vibration amplitude increased significantly.

Abstract: Industrial Radiography is the most widely accepted NDT technique for weld quality in industries. As it is an indirect method, defect type and nature must be obtained by analyzing the radiographs. Manual interpretation of radiographs is subjective in nature. So the paradigm shifted to automated weld defect detection system. Though considerable research is done in automated weld defect detection, an accurate domain specific technique has not yet been evolved due to noise, artifacts in radiographs, low contrast between the defect region and the background and difficulty in isolating the defect. The proposed work aims at developing an automated weld defect detection system that enhances the contrast between the object and the background and isolates the weld defect. In this work, real time weld radiographs are acquired and contrast enhancement is performed with DWT. Slag and Porosity are isolated and dimensionally characterized.

Abstract: Normal 0 false false false EN-US X-NONE X-NONE Friction-stir welding is a solid state welding. The aim of welding needs to be defect free which requires uniform distribution of weld bead. In this paper the parameters such as energy, maximum temperature and thermal conductivity involved during the Friction Stir Welding process is considered as numerical data and applied it over a Hyper Geometric Function and changes in Gamma values are studied. In Gauss hyper geometric function the thermal conductivity is taken as constant while the energy and maximum temperature developed is taken as numerical variables on the Gamma calculations. The model is applied to AA2024, AA7075 and AA6061. By Hyper Geometric investigation the uniformity of weld is found to be good for the taper tool geometry. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

Abstract: — For fabricating light weight structures, it requires high strength-to weight ratio. AA6061 aluminium alloy is widely used in the fabrication of light weight structures. A356 aluminium alloy has wide spread application in aerospace industries. Friction stir welding is solid state joining process which is conducting for joining similar and dissimilar materials. The friction stir welding parameters play an important role for deciding the strength of welded joints. In this investigation, A356 and AA6061 alloys were friction stir welded by varying triangular, square, hexagonal pin profiles of tool keeping the remaining parameters same and AA6061 alloys were friction stir welded by varying tool shoulder diameter as 12mm,15mm,18mm without changing other parameters. Tensile properties of each joint have been analyzed microscopically. From the experimental results, it is observed that hexagonal pin profiled tool and 15mm shoulder diameter tool provides higher tensile properties when compared to other tools.