and gas methods are both good. Braz- ing is not recommended. Corrosion Resistance—Tese alloys

exhibit good resistance to most com- mon forms of corrosion and react well to chemical conversion coatings for additional protection.

Alloy 356.0 Alloy 356.0 has excellent casting

characteristics (Table 2). Permanent mold castings of this alloy are used for machine tool parts, aircraft wheels and hand wheels, pump parts, tank car fittings, marine hardware, valve bodies and bridge railing parts, as well as for aileron control sectors, rudder control supports, fuselage fittings and fuel tank elbows for airplanes and mis- siles. Automotive applications include miscellaneous castings for trucks and trailers, spring brackets, cylinder heads, engine blocks, passenger car wheels and transmission cases. Uses for sand castings of 356.0

include flywheel housings, automo- tive transmission cases, oil pans, rear axle housings, brackets, water-cooled cylinder blocks, various fittings and pump bodies. Tis alloy is used in various marine applications in the T6 condition where pressure tightness and/or corrosion resistance are major requirements. Castability—Fluidity, resistance to hot cracking and resistance to so-

lidification shrinkage are excellent for 356.0 alloy. Machinability—After heat treat- ment (notably in the T6 condition), 356.0 has good machinability. Because of the high silicon content, savings can be realized by using carbide-tipped cutting tools. Rakes must be positive and high. Speeds must approach the maximum, and light cuts must be taken. Finishing—Alloy 356.0 has good polishing characteristics. It is excellent for electroplating and good for chemical conversion coatings. Anodizing appear- ance is good, and the color is gray. Weldability—Good welding char-

acteristics are shown by 356.0 for all standard welding methods. Te alloy is not brazed. Corrosion Resistance—Excellent

resistance to corrosion is shown by 356.0. Chemical conversion coatings give further protection.

Alloy A356.0 Due to lower levels of impurities,

alloy A356.0 has greater elongation, higher strength and considerably higher ductility than 356.0. Typical applications are airframe castings, ma- chine parts, truck chassis parts, aircraft and missile components, and structural parts requiring high strength. Castability—All casting character-

istics are excellent for this alloy. Machinability—Alloy A356.0 has

good machinability after heat treating. Abrasiveness can be overcome and high tool wear can be minimized by using sharp, carbide-tipped tools with high rakes and clearances. Moderate to fast speeds are recommended. Finishing—Electroplated finishes

are good. Chemical conversion coat- ings give good protection, but anod- ized appearance is only fair. Mechani- cal finishes on A356.0 are good. Weldability—All common welding methods are excellent for joining this alloy. Brazing is not performed. Corrosion Resistance—This alloy

has good resistance to most forms of corrosion.

Alloys A380.0 and B380.0 Tese alloys are used for producing

general purpose die castings. Tey have good mechanical properties and are used to make housings for lawn mow- ers and radio transmitters, air brake castings, gear cases and air-cooled cylinder heads. Castability—Fluidity, pressure tightness and resistance to hot crack- ing all are good. Machinability—Although the

machinability of A380.0 and B380.0 is considered good, carbide-tipped tooling is recommended because of the alloys’ tendency to be abrasive. Tools should be sharp with high rake and clearance angles, and machines should be operated

This laser housing for the industrial and scientific markets was cast in A356 aluminum alloy with T51 heat treatment. 44 | METAL CASTING DESIGN & PURCHASING | Jul/Aug 2016

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