🔩 ALUMINUM
Forged Aluminum Components: Grades, Tempers & Sourcing
Aluminum forges hot in a narrow window most people underestimate. Unlike steel, the alloy goes from forgeable to torn in a swing of 100°F, and the temper you specify is created after forging, not before. Buyers who treat aluminum forging like aluminum machining usually order the wrong grade.
AS9100ISO 9001NADCAP
Why Forge Aluminum Instead of Machine From Plate
The argument for forging aluminum is grain flow. When you machine a bracket from 7075 plate, you cut across the rolling grain and expose end grain at the most loaded surfaces. A forged part follows the die contour, so the grain wraps around fillets and bosses, which is where fatigue cracks initiate. For rotating or cyclically loaded aerospace parts, forged 7075 routinely shows 20-30% higher fatigue strength than the same alloy machined from billet.
The second reason is material utilization at volume. A wheel spider or landing-gear fitting machined from solid can throw away 80-90% of the billet as chips. Closed-die forging gets you near-net, so for runs above a few hundred pieces the buy-to-fly ratio and chip cost collapse. Below that volume, the die cost (often $15,000-$60,000 for a closed impression die) does not amortize and you should machine from billet or use an open-die preform.
The catch: forging does not fix a bad alloy choice. If the part needs to be welded and anodized clear, no amount of grain flow saves you from picking 6061 over 7075. Forging is a strength and economics decision layered on top of the metallurgy, not a substitute for it.
Grade Behavior: 6061, 7075, 2024 and 5052 Under the Hammer
6061 is the workhorse forging alloy. It flows well, fills thin ribs, and forges around 750-850°F. After forging it solution treats and ages to T6, giving roughly 45 ksi tensile and excellent corrosion resistance. It is the default for structural brackets, hydraulic manifolds and anything that will be welded.
7075 is stronger (up to 83 ksi in T6) but forges in a tighter temperature band and is far more crack-sensitive at the die. Aerospace almost always specifies the T73 or T7351 overaged temper for forged 7075 because peak-aged T6 is vulnerable to stress-corrosion cracking in the short-transverse direction, exactly where forging concentrates stress. You trade about 10% strength for SCC immunity. 2024 forges similarly to 7075, is chosen for damage tolerance and fatigue, and is usually aged to T4 or T351.
5052 is the odd one out: it is non-heat-treatable, so you cannot age it for strength. It work-hardens, has superb seawater corrosion resistance and forms beautifully, but as a forging alloy it is rare. If someone asks for forged 5052, the honest answer is they almost always want a formed or stamped 5052 part, not a forging. Push them to 6061 if they need a true forged shape with strength.
Tolerances, Draft and the Post-Forge Reality
As-forged aluminum holds far looser tolerances than machined stock. A commercial closed-die aluminum forging holds roughly ±0.015 to ±0.030 in. on small features and more on large dimensions, with 3-7° of draft on side walls and 0.12-0.25 in. fillet radii. Precision (no-draft or near-net) forging tightens this but costs more in tooling and press tonnage.
Flash, parting-line mismatch and die wear all eat into your envelope, so any critical bore, mounting face or sealing surface gets machined after forging. Plan the part with forged stock allowance of 0.030-0.060 in. on machined surfaces. Trying to hold a bearing fit straight off the die is a recipe for scrap.
Heat treat distortion is the sleeper issue. Solution treating 7075 means quenching from around 900°F, and thin sections move. Sizing, straightening or restrike operations are common, and residual stress from the quench can cause parts to spring during finish machining. Good shops stress-relieve (the W51/T7351 stretch or compression step) before you cut, and you should ask for it on anything dimensionally critical.
Frequently Asked Questions
It depends almost entirely on whether you need a closed-die tool. Open-die and hammer forging with simple tooling can be economical at 25-100 pieces because there is no dedicated impression die, just blocks and a skilled operator. Closed-die forging carries a tool cost of roughly $15,000-$60,000 for an aluminum impression die, so you generally need 250-1,000+ pieces before the per-part savings beat machining from billet. For prototypes or runs under 50, most buyers machine 6061 or 7075 from plate or billet, accept the chip loss, and switch to forging once volume justifies the tool. Ring rolling is a separate case: forged aluminum rings (flanges, bearing races) can be cost-effective in the low hundreds because the tooling is generic. Always get a buy-to-fly and amortized tool quote both ways before committing.
Peak-aged 7075-T6 has the highest strength, around 83 ksi tensile, but it is highly susceptible to stress-corrosion cracking in the short-transverse grain direction. Forging deliberately creates strong directional grain flow, and the short-transverse direction ends up in the worst possible orientation at fillets and parting lines where residual and service stresses concentrate. T73 (and T7351, which adds a stress-relief stretch) is an overaged temper that drops strength roughly 10-15% to about 70 ksi but makes the alloy essentially immune to SCC. For aerospace structure, landing gear and anything exposed to humidity or chlorides, the durability is worth far more than the strength you give up. AMS specs like AMS 4147 for 7075 forgings call out these tempers. If a vendor offers you forged 7075-T6 for a structural application without flagging SCC, that is a red flag.
Yes, but the answer is grade-dependent. 6061 forgings weld readily with 4043 or 5356 filler and anodize to a clean, uniform finish, which is why it dominates forged manifolds, housings and weldments. 7075 and 2024 are effectively non-weldable by conventional fusion methods because they crack in the heat-affected zone and lose temper, so design those as fastened or bonded assemblies. For anodizing, 6061 and 5052 take clear and color anodize beautifully; high-copper alloys like 2024 anodize darker and less uniformly because copper does not anodize cleanly, often giving a yellowish or smutty appearance. Hard-coat (Type III) anodize on forged 6061-T6 adds 0.002-0.004 in. of wear surface and is common on hydraulic and pneumatic forgings. Always anodize after final machining, since the coating builds on the surface and will throw tight tolerances out of spec by half the coating thickness per side.
First-article forging lead time is dominated by tooling. Expect 6-12 weeks to design, cut and prove a closed-die aluminum impression die, then 2-4 weeks for the production forging run plus heat treat (solution + age adds about 1-2 weeks including queue) and finish machining. So a true first article from a cold start is commonly 12-20 weeks. Once tooling exists, reorders run 4-8 weeks depending on heat-treat and machining backlog. By contrast, machining the same part from 6061 or 7075 billet can deliver first articles in 2-4 weeks with zero tooling. That gap is exactly why programs prototype from billet and convert to forging for production: you de-risk the design on machined parts, then commit to the die once the geometry is frozen. Budget extra calendar time if NADCAP heat-treat or AS9100 source inspection is required.
As-forged aluminum surfaces typically run 125-250 µin Ra, depending on die condition, lubricant and whether the part was shot-blasted to clean scale and lubricant residue. That is fine for non-critical webs and ribs but nowhere near sealing or bearing quality. Any surface that mates, seals or carries a bearing gets machined to 32-63 µin Ra, and ground or honed surfaces go finer. Forging also leaves a parting-line flash witness and possible die-lock marks that buyers should expect to clean up. One advantage over castings: forged aluminum has no porosity, so machined surfaces are sound and leak-tight, which matters for hydraulic and pneumatic bodies. If cosmetic appearance matters, budget for vibratory finishing or bead blasting after machining, and specify it on the drawing rather than assuming the forge shop will do it.
Last updated: July 2026
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