Conventional casting

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. 

The softening point of conventional cast and sheet iron enamels is about 500°C, but special compositions are obtainable which operate successfully at 600°C. Other more specialised enamels withstand service conditions ranging from being in excess of dull red heat, e.g. as obtained in fire backs, to those capable of enduring short exposure to temperatures of around 1 000°C, e.g. in jet tubes, after burners, etc. 

Water Permeation and Solute Separation through the Membrane. The measurements of water permeability of the 67 membranes prepared under different conditions were carried out by using an Amicon Diaflo Cell (effective membrane area, 13.9 cm2) under a pressure of 3 kg/cm2 at 25 °C. Some results are listed in Table 1067. It is apparent that much higher water absorption and permeability than the cellulosic membrane are characteristic of the 67 membranes prepared by both the casting polymerization and conventional casting. 

The coarse grains developed by conventional casting processes usually arc deleterious to fatigue life. For parls such as turbine disks that arc life-limited by latiguc rather than creep, fine grains are produced by powder metallurgical techniques. 

Figure 7.10 Comparison of (a) dendritic conventionally cast and (b) nondendritic semisolid formed microstructure of aluminum alloy 357 (Al-7.0 Si-0.5 Mg). The photos are at the same magnification. (From M. Kenney, in ASM Handbook, Vol. 15, Casting, D. M. Stefanescu, Ed., 1988, p. 327. Reprinted with permission of ASM International. All rights reserved, www.asmintemational.org.)...

Conventional casting (air-cooled) Coarse-grained polycrystaUine hulk solids... 

The OPS extrusion process is distinguished from conventional cast extrusion (unoriented) processes by the additional energy requirements of the MDO and TDO units. Cast extrusion processes generally require 0.2-0.7kWh per kilogram of extruded product. The OPS process requires 0.7-0.9 kW h per kilogram of extruded product, which increases conversion cost. 

Firstly, a kinetic Monte Carlo (kMC) [8] for the nano-structural evolution of so-called spongy nickel from the constituent intermetallic phases present in nickel-aluminium precursor alloys is described. Experimental data concerning nano-porous nickel catalyst powder used in this paper are derived from leached NiAl alloy powder produced via a spray-atomization route rather than the conventional cast-and-crushed route. 

Under conventional casting conditions (without ultrasonic cavitation), the supercooling of a melt arising at the solidification front can spread into the liquid metal with a simultaneously decrease of the degree of supercooling. This process is due to convective streams and, particularly, due to forced movement of the melt with electromagnetic or mechanical stirring. 

Table II. Run parameters on a conventionally cast gel separated on an MRA Cold Focus apparatus for hemoglobin separation. Gel, 5 % T, 3. 5% C, 250 i thick and ambient temperature 17° C. Ampholyte 4 per cent Pharmacia pH 6-8 with a distance of 5.4 cm between electrode wick edges. Catholyte 1.0 M NaOH, anolyte 1.0 M H3PO4. Time given in minutes.

One-step processing for superplasticity from cast sheet or hot-pressed powder metallurgy sheet A conventionally cast microstructure can be converted to a superplastic microstructure in many steps. The present process of microstructural refinement can be used directly on cast sheets. This leads to very economical manufacturing. Ma et al. (Ref 46)... 

A major application of superalloys is in turbine materials and jet engines, both disc and blades. Initial disc alloys were Inco 718 and Inco 901, produced by conventional casting ingot, forged billet, and forged disc route. These alloys were developed from austenitic steels, which are still used in industrial turbines, but were later replaced by Waspaloy and Astroloy as stress and temperature requirements increased. These alloys were turbine blade alloys with a snitably modified heat... 

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