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Aluminum alloys have been attracted by several engineering sectors due to their excellent strengthweight ratio and corrosion resistant properties. These are categorized into 1, 2, 3, 4, 5, 6, 7and 8xxx on the basis of alloying elements. Among these 6xxx series contains aluminum–magnesium–silicon as alloying elements and are widely used in extruded...
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Tensile and impact strengths of 304L SS stainless steel weldment prepared at different levels of heat treatments and with vibratory assistance were studied and compared with the conventional process of welding. The results reveal that the microstructures of weld joints after heat treatment and vibratory welded joints attained a fine grain structure...
Citations
... The nucleation rate of Mg2Si precipitates rose with increasing aging temperature. They also deduced that highest value of strength, elongation, toughness and hardness is obtained at 240oC because of Mg2Si precipitation with intermediate grain size and uniform distribution [13,14]. The researchers Ozturk et al conducted aging treatment procedure for 6061 alloy and they found that after 200 minutes of aging at 200oC, the peak-aging conditions are reached. ...
... Increasing number of the solid precipitates in the microstructure makes the material more brittle [17]. The β" phase is rich in dislocations [18,19]. Increasing temperature decreases the number of dislocations [20]. ...
6XXX series aluminum alloys are generally excellent alternatives to steels for many forged parts in aerospace and automotive industries. In this study, the forging performance of the 6082 aluminum alloy is investigated in order to replace the existing material for forged steel parts. The effect of artificial aging of the alloy on the microstructure and mechanical properties is studied. Optimum aging conditions are determined. Results reveal that AA6082 could be a good replacement for applications where shock and vibrational loads exist. The rod end automotive part currently manufactured from AISI1045 can be replaced by AA6082 without any design changes. The major drawback is that the cold forging of the aged alloy is poor due to its brittle nature and crack initiations. Therefore, warm or hot forging is recommended to overcome the poor forgeability.
... Aluminium is very light and is highly attracted by modern manufacturing technologies. It is reported that worldwide 90% aluminium alloys pipes and tubes are manufactured from 6xxx aluminium alloy [1]. This type of aluminium alloy is heat treatable and contains Si and Mg as a major alloying element. ...
... The higher hardness of as-cast alloy samples A1 and D1 could be attributed to micro segregations present in the Al-Zn-Cu-Mg structure that embrittled the alloy. It has been established that the smaller the grain boundaries, the harder and stronger the metal [17]. Fig. 8 shows the as-cast sample A1 (0.77Cu 17.03Zn 80.33Al), Sample B1 (1.56Cu 17.14Zn 80.16Al 0.001 Mg), Sample C1 (1.26Cu 9.7Zn 87.6Al 0.33 Mg) and Sample D1 (2.17Cu 13.99Zn 80Al 0.6 Mg), and precipitation hardened samples A2, B2, C2, and D2. ...
The microstructure and mechanical properties of Al-Zn-Cu alloy with magnesium inclusion varying between 0.5 and 1.5 wt% were explored in this investigation. Al-Zn-Cu-Mg alloy was prepared by sand casting. Heat-treatment was done on the cast alloy samples at 460 C for 2 h, which was then waterquenched. The samples at 160 C were age-hardened for 5 h. Mechanical tests were done on both the heat-treated and as-cast alloy samples. Optical and scanning electron microscopy were used for the surface morphology of the samples. The maximum tensile strength (178.04 N/mm2) and hardness value (42.49 HB) were obtained from the Al-Zn-Cu-Mg alloy samples with 0.33 wt% Mg and 0.001 wt% Mg, respectively. In the as-cast samples, the reinforcing intermetallic phases present was coarse in nature while the precipitation hardened samples showed well-distributed reinforcing intermetallic phases which are fine grain size. Hence, the tensile strength of the cast Al-Zn-Cu-Mg alloy was positively influenced with theaddition of magnesium while precipitation hardening eliminates micro segregations, thus, Al-Zn-Cu-Mg alloy mechanical properties were improved. Thus, the Al-Zn-Cu-Mg alloy can be useful in automobile industry.
... Increasing the number of the solid precipitates in the microstructure makes the material brittle [17]. The β'' phase is rich in dislocations [18,19]. Increasing temperature decreases the number of dislocations [20]. ...
6XXX series aluminum alloys are generally excellent alternatives to steels for many forged parts in aerospace and automotive industries. In this study, the forging performance of the 6082 aluminum alloy is investigated in order to replace the existing material for forged steel parts. The effect of artificial aging of the alloy on the microstructure and mechanical properties is studied. Optimum aging conditions are determined. Results reveal that AA6082 could be a good replacement for applications where shock and vibrational loads exist. The rod end part currently manufactured from AISI1045 can be replaced by AA6082 without any design changes. The major drawback is that the cold forging of the aged alloy is poor due to its brittle nature and crack initiations. Therefore, warm or hot forging is recommended to overcome the poor forgeability.
... Higher aging temperature causes shorter time to reach aging. On the other hand, too lengthy precipitation setting time results in a larger size of the precipitate which causes its strength to decrease [11]. The strength of AA 6061 can be increased by artificial aging treatment with a holding time of up to 2 hours. ...
Friction welding is a solution for metal joint problems that are difficult to joint with fusion welding. The quality results of friction welding are highly dependent on process parameters such as friction pressure, friction time, forging pressure, forging time, and rotating speed. There is often excessive softening, hardening of the metal grains, and formation of an intermetallic phase at the weld interface due to too high friction temperatures and too high forging pressures on the alloy. Several studies on AA 6061 concludes artificial aging heat treatment can provide positive changes on the tensile strength and microstructure of AA 6061. The purpose of this study is to find out the effect of post artificial aging treatment toward profile and mechanical properties of AA 6061 friction welding joint. The varied parameters are forging pressure in friction welding of 325 bar, 350 bar, 375 bar and artificial aging heating temperature post-welding of 100 °C, 150 °C and 200 °C. The fixed parameters observed are the connection profile, microstructure, hardness distribution and tensile strength of the joint. Controlled variables include: 1600 rpm spindle rotation, 65 bar or 65 kg cm ⁻² friction pressure, friction time tf = 6 seconds, time forging pressure tu = 60 seconds, workpiece contact diameter 15 mm and 15 degrees workpiece chamfer angle. The results are specimens with forging pressures of 325 bar, 350 bar and 375 bar without artificial aging treatment still show clearly interface of Zpl and Zpd zone; whereas in specimens treated with artificial aging, the Zpd and Zpl interface are getting faded which indicating that there is structures homogenization in the Zpd and Zpl zone. The hardness of the joint area increased significantly after artificial aging heat treatment because formed Mg 2 Si precipitates were dispersed in the Zpl, Zpd and Zud zones. The post-weld artificial aging heat treatment also resulted in a more even distribution of hardness in the joint area. The highest distribution of joint area hardness occurred in specimens with a forging pressure of 350 bar and artificial aging treatment at 200 °C. Artificial aging treatment with a temperature of 200 °C will form Mg 2 Si (black) precipitation and Fe 3 SiAl 12 (gray) particles which are evenly dispersed in the Al matrix in the Zpd and Zpl zones so that their hardness is high. By applying artificial aging heat treatment, the tensile strength of the specimens increases until the artificial aging temperature is 150 °C; when the artificial aging temperature is raised to 200 °C, the tensile strength tends to drop back.
Sri Lanka being country rich with Tuna fish resource, is one of the oldest islands producing Maldives fish in the Indian Ocean. In Maldives fish processing, drying is an important unit operation which ultimately determine the quality of the end product. A natural convection type drying and smoking unit was designed to overcome the limitations of sun drying which is the most common practice at present and to produce a good quality product with required nutritional properties, aroma, texture and flavor. In designing, factors such as affordability to the fishing community, optimum use of land area and user-friendliness were also considered apart from performance. In preliminary testing of the smoking and drying unit, 1000 kg of fresh skip jack tuna (Katsuwonus pelamis) fish were dried after salting boiling and smoking. The drying temperature was maintained around 450C by controlling the rate of feeding the fuel wood manually. Drying completed in 4 days while feeding fuel wood only in day time so that total operation time was 48 hours. The level of water activity, sensory properties and the physical observation of the dried product showed that Maldives fish of accepted quality was produced in the test operation of the dryer. Further improvements of the smoking and drying unit were identified for the better performance.
Keywords: Maldives fish, Fish Smoking, Fish drying
AlSi9Mg aluminum alloy flywheel housing components were formed via squeeze casting and T6 heat treatment was applied to the formed components. The influence of solid solution temperature, solid solution time, aging temperature and aging time on the microstructure and mechanical properties of AlSi9Mg aluminum alloy components formed by squeeze casting were investigated. The results showed that T6 heat treatment changed the morphology of the eutectic silicon in the microstructure from long fibrous to short rods and round spheres. The spheroidization of eutectic Si phase was more obvious with an increase of solution temperature, and the eutectic Si phase not dissolved in the matrix became coarse and grew with an extension of solution time. In terms of mechanical properties, the tensile strength and elongation of AlSi9Mg specimens after heat treatment showed an increasing trend with a rise of solution temperature, but the yield strength decreased, while the three mechanical properties of specimens all improved first and then decreased with an increase of solution time, aging temperature and aging time. Comprehensive consideration of three mechanical properties showed that the optimal heat treatment process parameters in this experiment were solution temperature of 540 ℃, solution time of 180 min, aging temperature of 175 ℃ and aging time of 300 min. In addition, β''−Mg2Si strengthening phases and disc-shaped strengthening phases were precipitated during T6 heat treatment, which were also one of the reasons for the improvement of the casting properties.
New area industry of Albania, in recent years, factories with closed cycle of production and processing of aluminium alloys are being targeted. In Albania about 25,000 tons of aluminum alloys per year are produced and there is a tendency to increase this production. This reality has encouraged us to undertake a number of studies with the primary objective for optimizing the parameters of t he basic process of this industry. In this article we focus on the process of artificially aging aluminum alloys. From early and newer studies [2], the importance and delicacy of temperature-time parameters in the evolution of microstructure and in the mechanical properties of the final product are recognized and underlined. We have impost an experimental planning based on the Response Surface Method by choosi ng Central Composite Design to optimize the temperature and time parameters for the artificial aging with the objective of maximizing the process indicator-mechanical properties, hardness in our case. The plan includes 13 tests with 5 replicas in the center of the experiment, built with the help of Design-Expert DX7 and DX13 software. The focus of our attention was the assesment of the design, analysis of residuals and diagnostic diagrams and forms of presentation of results: mathematical model, 3D response surface, isocontours and effects of interaction between factors. In the future works we will present the experimental results of the optimization of the artificial aging process for different aluminium alloys produced in Albania.
