Cast mechanical properties

Based on factors such as cast, mechanical properties, physical properties, ease of fabrication (design) and the corrosion resistance data available in the literature the choice of materials can lead to a short list of two or three materials. At this stage it is prudent that the engineer design prototype laboratory scale model equipment from the short-list of selected metals or alloys, and determine the corrosion rates in the environment of interest. These accelerated tests will enable the engineer to select the best candidate material, making proper allowance for the corrosion of the metal or alloy over the lifetime of the equipment. 

Modijication and grain rejining For aluminium alloys this usually involves the addition of small amounts of metal to the melt. These additions control the grain size and modify the microstructure of the solidifying metal and thus enhance the casting mechanical properties. Sodium or strontium are used for the modification, while grain refinement is achieved with titanium, titanium boride, zircon or carbon. This treatment is mostly performed in combination with degassing in a dedicated metal treatment station... 

Ares, A.E. Caram, R. Schvezov, C.E. (2006) Relation between As-Cast Mechanical Properties, Microstructure and Solidification Conditions for Zn-Al Alloys, Proceedings of MCWASP International Conference Modeling of Casting, Welding and Advance Solidification Processes - XI, Opio, France, June of 2006... 

Table 2. Clear casting mechanical properties [from Ref. 32].

NONDESTRUCTIVE MAGNETIC METHID OF INSPECTION OF THE MECHANICAL PROPERTIES OF CAST STEELS. 1. CONSTRUCTION OF CORRELATION MODELS and II. PRACTICAL APPLICATION OF CORRELATION... 

Trimethylolethane trinitrate (metriol trinitrate) is not satisfactory as a plasticizer for nitrocellulose, and must be used with other plasticizers such as metriol triacetate. Mixtures with nitroglycerin tend to improve the mechanical properties of double-base cast propellants at high and low temperatures. Metriol trinitrate has also been used in combination with triethylene glycol dinitrate as a plasticizer for nitrocellulose. Its physical properties are Hsted in Table 7 (118-122). 

The resin, catalyst, and microhalloons are mixed to form a mortar which is then cast into the desirable shape and cured. Very specialized electrical and mechanical properties may be obtained by this method but at higher cost. This method of producing cellular polymers is quite appHcable to small quantity, specialized appHcations because it requires very tittle special equipment. 

Dentistry. Most casting alloys meet the composition and properties criteria of specification no. 5 of the American Dental Association (37) which prescribes four types of alloy systems constituted of gold—silver—copper with addition of platinum, palladium, and 2inc. Composition ranges are specified, as are mechanical properties and minimum fusion temperatures. Wrought alloys for plates also may include the same constituents. Similarly, specification no. 7 prescribes nickel and two types of alloys for dental wires with the same alloy constituents (see Dental materials). 

Rea.ctivity ofLea.d—Ca.lcium Alloys. Precise control of the calcium content is required to control the grain stmcture, corrosion resistance, and mechanical properties of lead—calcium alloys. Calcium reacts readily with air and other elements such as antimony, arsenic, and sulfur to produce oxides or intermetaUic compounds (see Calciumand calciumalloys). In these reactions, calcium is lost and suspended soHds reduce fluidity and castibiUty. The very thin grids that are required for automotive batteries are difficult to cast from lead—calcium alloys. 

Cast lead—calcium—tin alloys usually contain 0.06—0.11 wt % calcium and 0.3 wt % tin. These have excellent fluidity, harden rapidly, have a fine grain stmcture, and are resistant to corrosion. Table 4 Hsts the mechanical properties of cast lead—calcium—tin alloys and other alloys. 

Table 4. Mechanical Properties of Cast Lead Alloys...

Wrought lead—calcium—tin alloys contain more tin, have higher mechanical strength, exhibit greater stabiUty, and are more creep resistant than the cast alloys. RoUed lead—calcium—tin alloy strip is used to produce automotive battery grids in a continuous process (13). Table 5 Hsts the mechanical properties of roUed lead—calcium—tin alloys, compared with lead—copper and roUed lead—antimony (6 wt %) alloys. 

Wrought lead—calcium—tin anodes have replaced many cast lead—calcium anodes (14). Superior mechanical properties, uniform grain stmcture, low corrosion rates, and lack of casting defects result in increased life for wrought lead—calcium—tin anodes compared to other lead alloy anodes. 

P/M processing of titanium aluminides results in more consistent product quaHty than the conventional casting process, and offers novel alloy/microstmcture possibiHties and improved ductiHty. Processing trends include use of high (1200—1350°C) temperature sintering to improve mechanical properties of steel and stainless steel parts. 

Mechanical Properties. The performance of various polyester resin compositions can be distinguished by comparing the mechanical properties of thin castings (3 mm) of the neat resin defined in ASTM testing procedures (15). This technique is used widely to characterize subtle changes in flexural, tensile, and compressive properties that are generally overshadowed in highly filled or reinforced laminates. 

S, sand cast P, permanent mold cast D, pressure die cast. Aluminum and impurities constitute remainder. Table 22. Mechanical Properties of Aluminum Foundry Alloys ... 

Copolymerisation also affects morphology under other crystallisation conditions. Copolymers ia the form of cast or molded sheets are much more transparent because of the small spheruHte size. In extreme cases, crystallinity cannot be detected optically, but its effect on mechanical properties is pronounced. Before crystallisation, films are soft and mbbery, with low modulus and high elongation. After crystallisation, they are leathery and tough, with higher modulus and lower elongation. 

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