Processing, aluminum alloys castings

Z.Y. Ma, R.S. Mishra, and M.W. Mahoney, Friction Stir Processing for Microstructural Modification of an Aluminum Alloy Casting, Friction Stir Welding and Processing II, Proceedings,... 

Uses. Alkah metal and ammonium fluoroborates are used mainly for the high temperature fluxing action required by the metals processing industries (see Metal surface treatments Welding). The tendency toward BF dissociation at elevated temperatures inhibits oxidation in magnesium casting and aluminum alloy heat treatment. 

Aluminum alloys are commercially available in a wide variety of cast forms and in wrought mill products produced by rolling, extmsion, drawing, or forging. The mill products may be further shaped by a variety of metal working and forming processes and assembled by conventional joining procedures into more complex components and stmctures. 

The thickness of the enamel layer varies with the type of use and metai. However, typical thicknesses are from 75 to 150 pm t.3 to 6 mils) for sheet steel, 175 to 359 pin (7 to 14 mils) for hot-rolled steel. 100 to 125 pm 4 to 5 mils) Tor each coat of wet process cast iron (760 lo 7RR C fire). 15 lo 25 pm (0.5 to I mil) for dry process cast-iron base coats and 750 pm (average) to nearly 2250 pm (30 mils to 90 mils) for ihe dusted cover coats (898 to 955 C tires), and 25 to 50 im (I to 2 mils) for aluminum alloys. Stainless steel and copper may have enamel coalings from 40 pm to 175 pm 11.5 to 7 mils) ihick. 

Microstructure evolution in solids formed from a melt is important in processes such as prilling or casting. For example, in aluminum alloy shape casting the final microstructure depends directly on the as-cast microstructure since the only post-casting process is the heat treatment. The micro-porosity formed owing to the combined effects of the volumetric shrinkage upon the solidification of the melt and the precipitation of the dissolved hydrogen affects the final properties of the aluminum alloy. 

POSTER TITLE Mechanical properties of AA7068 aluminum alloy fabricated by twin roll casting and rolling processes (PAPER ID 8851)... 

Process piping-carbon steel, alloy, cast iron, lead, lined, aluminum, copper, ceramic, plastic, rubber, reinforced concrete Pipe hangers, fittings, valves Insulation-piping, equipment... 

Aluminum pistons in an engine that bums H2 will be exposed to not only H2 but also H2O at temperatures of 80 to 120°C. Aluminum alloys can be totally immune to H2 embrittlement and H2-induced crack growth if the natural AI2O3 oxide is intact. However, there are processes that can disrupt this film, and it is known that aluminum alloys will absorb H2 when exposed to H2O vapor at 70°C. There will also be periods when the engine is cool and condensed water will be present so that aqueous corrosion could occur, but this is not expected to be any different than with an engine with cast aluminum pistons that bums gasoline. 

Metallurgical grade silicon plays an important role as an alloy constituent in aluminum alloys. Addition of 2-25% improve the casting properties of aluminum in the manufacture of castings for example for engine blocks or cylinder heads. The utilization of metallurgical grade silicon in the manufacture of methylchlorosi lanes and the silicones produced therewith by direct synthesis (Rochow process) is covered in Chapter 4. 

Some studies have been performed on the continuous casting of aluminum alloys with UST in Japan (Furucawa Co.) and on an intensification of various metallurgical processes using ultrasound in China [27],... 

Similar dependencies are inherent in processes of ultrasonic degassing of the majority of industrial wrought aluminum alloys as well as aluminum alloys for shape casting. 

One of the first successful attempts of ultrasonic degassing of aluminum alloys for shape casting was the development of the process of the ultrasonic treatment in a crucible with the stationary volume of up to 200 kg [3-5,49]. 

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