NONFERROUS ALLOYS CHEAT SHEET
Save this article for the next time you need a quick reference guide on nonferrous casting materials.
AN MCDP STAFF REPORT ALUMINUM
CASTING PROCESS COMPATIBILITY Aluminum is compatible with most available metal-
casting processes: • Green sand. • Nobake. • Diecasting. • Permanent mold. • Investment. • Lost foam. • Shell mold. • Centrifugal. • Plaster mold. • V-process.
DESIGN CONSIDERATIONS • Design complexities can have various effects on component cost. In some cases, the fi nished compo- nent cost can be reduced by in- cluding features in the design that will produce a near-net-shape part and minimize additional costs from post-casting processes, such as machining.
• Adding complex features can increase the cost of the casting. Lower cost processes, such as per- manent mold or diecasting, can be effective with aluminum, but they require higher tooling costs.
PROCESSING CONSIDERATIONS • To improve properties and enhance strength and ductil- ity, aluminum castings often are thermally processed by a series of heating and cooling cycles (solu-
tion, quench and age) called heat treatment.
• If high strength is required, heat-treatable alloys must be used. The alloy options can be narrowed further when considering the remaining require- ments, such as pressure tightness, corrosion resis- tance and machinability.
• Rarely are all of the desired properties optimized in a single aluminum casting. More often, heat treatment is a compromise, maximizing some properties at the expense of others. For example, tensile and yield strengths can be increased, but this results in lower elongation. Higher elongations result in lower tensile and yield strength.
This intake manifold for the heavy truck industry was convert- ed to A356 from steel.
Typical Mechanical Properties of Common Alloys* Alloy
Ultimate Strength (ksi)
201.0/A201.0 A206.0
319.0/A319.0 355.0 356.0
A356.0 535.0
60-68 51-63 27-40 23-45 24-32 23-41 40
Yield Strength (ksi)
37-60 36-50 18-27 12-40 18-27 12-30 20
Elongation %
5.5-17 7-12 1.5-3
0.5-4 2-6
3-12 13
* Ranges refl ect different casting processes and heat treatment conditions.
Hardness Bhn
130-146 -
70-95 65-105 60-80 75-90 70
34 | METAL CASTING DESIGN & PURCHASING | Jul/Aug 2012
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