Alloy 356.0 and A356.0

Alloy 356.0 has excellent casting characteristics and has largely replaced alloy 295.0.

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 missiles. Automotive applications include miscellaneous castings for trucks and trailers, spring brackets, cylinder heads, engine blocks, passenger car wheels and transmission cases.

Uses for castings of 356.0 include flywheel housings, automotive transmission cases, oil pans, rear axle housings, brackets, water-cooled cylinder blocks, various fittings and pump bodies. This 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 solidification shrinkage are all excellent for 356.0.

Machinability—After heat treatment (notably in the T6 condition), A356.0 has good machinability. Because of the high Si content, savings can be realized by using carbide-tipped cutting tools.

Finishing—Alloy A356.0 has good polishing characteristics. It is excellent for electroplating and good for chemical conversion coatings. Anodizing appearance is good, and the color is gray.

Weldability—Good welding characteristics are shown by 356.0 for all standard welding methods. The alloy is not brazed. Corrosion Resistance—Excellent resistance to corrosion is shown by 356.0. Chemical conversion coatings give further protection.

Alloy A356.0 has greater elongation, higher strength and considerably higher ductility than 356.0. It has these improved mechanical properties because impurities are lower in A356.0 than in 356.0. Typical applications are airframe castings, machine parts, truck chassis parts, aircraft and missile components, and structural parts requiring high strength. Castability—All casting characteristics are excellent for this alloy.

Machinability—Alloy A356.0 has good machinability. 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 coatings give good protection, but anodized appearance is only fair. Mechanical 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.

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