T6
Solution heat treated, quenched and artificially aged. Highest strength for 6xxx and 2xxx rings. Quenching leaves residual stress that can make a ring go out of round when it is machined.
Ring forgings
Aluminium Forged Rings and Seamless Rolled Rings
Aluminium rolled rings are seamless rings made by piercing a forged billet and rolling it out on a radial-axial ring mill, so the grain runs unbroken around the circumference. Forged rings made on open or closed dies suit thick, stepped and flanged sections. Metline supplies both in 6xxx, 2xxx and 7xxx alloys, heat treated, ultrasonically tested and certified to ASTM B247 or EN 586, to customers worldwide.
- Routes
- Ring rolling, open-die, closed-die
- Alloys
- 6061 · 6082 · 2014 · 2618 · 7075 · 7050
- Tempers
- T6, T652, T73, T7352, T74
- Standards
- ASTM B247 · EN 586 · AMS-STD-2154
What is an aluminium rolled ring?
A rolled ring starts as a sawn billet that is upset, pierced and punched into a thick "doughnut" preform. The preform is then squeezed between a driven main roll and a mandrel inside the bore, while a pair of conical axial rolls controls its height. Each revolution thins the wall and grows the diameter until the ring reaches size, with no weld anywhere in its circumference.
Because the metal is worked continuously around the ring, the grain flow follows the hoop direction, which is the direction in which most rings are loaded: bearing races, flanges, casings and pressure-retaining rings all carry hoop stress. Seamless rolling also removes the two weak points of fabricated rings, the weld bead and its heat-affected zone, and it uses far less metal than cutting a ring out of thick plate, where the centre disc becomes scrap.
Forged rings, by contrast, are shaped on flat or contoured dies. Open-die forging (sometimes called saddle or mandrel forging) expands a pierced blank over a bar, which suits thick walls and short production runs. Closed-die forging presses the ring in a cavity shaped like the part and is economic for repeat orders of small and medium rings with flanges, hubs or ribs. Many large rings are made by a combined route: a forged preform, ring rolling for wall uniformity, then a profiled rolling or machining step.
Seamless rolled ring or forged ring: which to choose
The diameter-to-wall ratio, the cross-section shape and the quantity decide the route. As a rule of thumb, thin-walled rings with a large diameter favour ring rolling; heavy, short, stepped or flanged sections favour die forging; and one-off prototypes favour open-die work or machining from a forged disc.
| Feature | Seamless rolled ring | Open-die forged ring | Closed-die forged ring |
|---|---|---|---|
| Typical geometry | Large diameter, thin to medium wall, rectangular or simple contoured section | Thick wall, short height, heavy sections | Small to medium rings with flanges, hubs, ribs |
| Grain flow | Continuous and circumferential | Circumferential, less uniform | Follows the die contour |
| Machining allowance | Low to moderate | Generous | Lowest |
| Tooling cost | Low (standard rolls) | None to low | High (dedicated dies) |
| Best quantity | Single pieces to large batches | Prototypes, short runs | Repeat production |
| Material yield | High | Moderate | High |
For rings above the size that a ring mill can roll in one piece, very large aluminium rings are sometimes made from segments joined by welding. These are not seamless and should be specified as such; for critical hoop-loaded parts we recommend confirming that a one-piece rolled ring is possible before accepting a segmented design. Our forged ring vs seamless rolled ring article compares the routes in more depth.
Aluminium alloys for rings and their typical properties
Almost any wrought aluminium alloy can be forged, but a small group covers nearly all ring work. The table lists typical room-temperature properties published for each alloy and temper. They are guides for comparing grades, not design values: ASTM B247 and EN 586-2 set minimums that depend on section thickness and test direction, and the values in the axial and radial directions of a ring are lower than in the tangential direction.
| Alloy / temper | Typical tensile | Typical yield (0.2 %) | Elongation | Where it fits |
|---|---|---|---|---|
| 6061-T6 | 310 MPa / 45 ksi | 275 MPa / 40 ksi | 12 % | General engineering, flanges, marine and food equipment |
| 6082-T6 | 310 MPa / 45 ksi | 260 MPa / 38 ksi | 10 % | European structural forgings, transport, offshore |
| 2014-T6 | 485 MPa / 70 ksi | 415 MPa / 60 ksi | 13 % | Heavily loaded fittings, wheels, gear blanks |
| 2618-T61 | 440 MPa / 64 ksi | 370 MPa / 54 ksi | 10 % | Parts working at 150 – 250 °C: impellers, pistons, engine rings |
| 2219-T6 | 415 MPa / 60 ksi | 290 MPa / 42 ksi | 10 % | Cryogenic tanks, rings that will be welded, hot-end parts |
| 7075-T6 | 570 MPa / 83 ksi | 505 MPa / 73 ksi | 11 % | Highest strength where stress corrosion is controlled |
| 7075-T73 | 505 MPa / 73 ksi | 435 MPa / 63 ksi | 13 % | Aerospace rings and fittings needing stress-corrosion resistance |
| 5083-H112 / O | 290 MPa / 42 ksi | 145 MPa / 21 ksi | 20 % | Seawater, cryogenic and welded assemblies |
Typical values from Aluminum Association and ASM published data. Order to the specified minimums of ASTM B247, EN 586-2 or the AMS specification on your drawing; the mill certificate reports tested values for each lot.
Two higher-strength aerospace alloys are also common for rings: 7050 in T74 or T7452, which keeps its properties through thick sections and resists stress-corrosion cracking better than 7075-T6, and 7175 for parts where fracture toughness is critical. For high-temperature service, 2618 is the classic choice, and 2219 combines good strength with weldability, which is why it is used for rocket fuel-tank rings that are welded to domes and barrels.
Tempers and stress relief for rings
T652
T6 plus a controlled cold compression or ring expansion after quenching to relieve stresses. Recommended when a ring will be machined heavily or to tight roundness.
T73 / T7352
Over-aged 7xxx tempers that trade about 10 – 15 % of strength for high resistance to stress-corrosion cracking. T7352 adds stress relief by compression.
T74 / T7452
Over-aged tempers for 7050 and 7075 that sit between T6 and T73 in strength and corrosion resistance. Widely used in modern aircraft forgings.
T61
The standard temper for 2618: solution treated, quenched in boiling water to reduce stress, then aged.
O / H112 / F
Annealed or as-forged conditions for 5xxx rings and for rings that will be heat treated by the customer after machining.
Heat treatment follows AMS 2770 or the customer specification, with furnace temperature uniformity, quench delay and quench-water temperature recorded for each load. Ask for the cycle records if your quality plan needs them.
Ring sizes, supply conditions and tolerances
Typical supply range
- Outside diameter
- From about 100 mm up to large rolled rings over 2 m; maximum depends on alloy, height and the ring mill used
- Wall thickness
- From about 10 mm; the practical minimum rises with diameter
- Height (axial)
- From about 20 mm; tall rings are rolled with axial control or forged
- Section shapes
- Rectangular, stepped, L-section and contoured; flanged and grooved by forging or machining
- Supply condition
- As forged or as rolled, rough machined (proof machined for UT), or finish machined to drawing
- Testing
- Tensile tests in tangential and axial directions, hardness, conductivity on 7xxx, ultrasonic inspection
Exact limits are confirmed against your drawing because ring mill and die capacity vary with alloy and section.
Unless the drawing says otherwise, rolled rings are quoted with a machining allowance on every face, typically a few millimetres per side, rising with diameter. Roundness and flatness are affected by heat treatment, which is why rings for precision parts are often ordered proof machined and stress relieved (T652 or T7352) before final machining. Dimensional tolerances for EN orders follow EN 586-3; for ASTM orders, tolerances are agreed with the drawing.
Ultrasonic inspection, testing and documents
Every ring forging is checked for dimensions and surface. For structural and aerospace rings, the most important test is ultrasonic inspection, which finds internal discontinuities such as unbonded laps or oxide films before machining time is spent on the part.
| Check | Standard or method | What it tells you |
|---|---|---|
| Ultrasonic inspection | ASTM B594 or AMS-STD-2154, class (AAA, AA, A, B) stated on the order | Internal soundness; class A or AA is usual for aerospace rings |
| Tensile test | ASTM B557 / EN ISO 6892-1, tangential and axial specimens | Strength and ductility in the loaded directions |
| Hardness and conductivity | Brinell or Rockwell; eddy-current conductivity | Confirms temper; conductivity screens 7xxx over-aging |
| Heat-treatment records | AMS 2770 / customer specification | Traceable furnace and quench data for each load |
| Dimensional report | Callipers, CMM or dedicated gauges | OD, ID, height, roundness and flatness against drawing |
| Certification | EN 10204 3.1 (3.2 with third-party witness on request) | Chemistry, properties and test results for the lot |
Ultrasonic testing works best on machined surfaces, so rings that need class AA or AAA inspection are normally supplied rough machined to a simple rectangular "sonic shape" first. Specify the class and the scanning directions on the order, because the cost of inspection rises sharply between class B and class AA.
Where aluminium rings are used
- Aerospace: engine casing and fan-case rings, fuselage and frame rings, rocket inter-stage and fuel-tank rings (2219, 7050, 7075)
- Defence: turret rings, launcher and missile body rings where weight and full traceability matter
- Industrial machinery: slewing ring housings, bearing carriers, rotary-table and indexing rings
- Energy: generator and turbine fittings, flanges for lightweight pressure equipment
- Vacuum and semiconductor: chamber rings and flanges in 6061, which machine cleanly and anodise well
- Cryogenics and LNG: 5083 and 2219 rings, which keep or gain toughness at very low temperatures
- Transport: wheel and hub blanks, gear and coupling rings in 6061, 6082 and 2014
For flanges and rings that will be welded into an assembly, choose an alloy that welds well (5083, 6061, 6082 or 2219) and design for the reduced strength of the heat-affected zone. 7075 and 2014 are not considered fusion-weldable for structural use.
How to order forged and rolled rings
- SpecifyAlloy and temper, OD × ID × height or a drawing, quantity, supply condition (as rolled, rough machined or finished), and the governing standard (ASTM B247, EN 586 or an AMS specification).
- Define qualityUltrasonic class and standard, test directions, any third-party inspection and the certificate type (EN 10204 3.1 or 3.2).
- ReviewWe propose the forging route and machining allowance and confirm tolerances and delivery terms (EXW, FOB, CIF or DAP).
- Produce and testRing forged or rolled, heat treated, tested and dimensionally inspected; reports are compiled per lot.
- ShipRings are protected against corrosion and impact, crated or palletised for sea or air freight, with certificates and packing list.
References and standards
- ASTM B247 – Aluminum and Aluminum-Alloy Die Forgings, Hand Forgings, and Rolled Ring Forgings
- EN 586-1/-2/-3 – Aluminium and aluminium alloys: forgings (delivery conditions, properties, tolerances)
- ASTM B594 – Ultrasonic Inspection of Aluminum-Alloy Wrought Products
- SAE AMS-STD-2154 – Inspection, Ultrasonic, Wrought Metals
- SAE AMS 2770 – Heat Treatment of Wrought Aluminum Alloy Parts
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
Aluminium forged and rolled rings: frequently asked questions
What is the difference between a forged ring and a seamless rolled ring?
Both are forgings. A seamless rolled ring is made by piercing a billet and rolling it out on a ring mill, so its grain flows continuously round the circumference and its wall is very uniform. A conventional forged ring is shaped on open or closed dies and suits thick, stepped or flanged sections and small batches.
Is a rolled ring stronger than a ring cut from plate?
In the hoop direction, yes. A ring trepanned from plate has grain running straight across it, so half of its circumference is loaded across the grain. A rolled ring has grain aligned with the hoop stress, which improves fatigue life and toughness and wastes far less metal.
Which aluminium alloy is best for a rolled ring?
6061-T6 is the economical general-purpose choice. 2014-T6 and 7075 give higher strength; 7075-T73 or 7050-T74 are preferred in aerospace for stress-corrosion resistance; 2618-T61 is used at elevated temperature; 5083 and 2219 suit welded and cryogenic rings.
Which standard covers aluminium rolled ring forgings?
ASTM B247 (B247M in metric units) covers die, hand and rolled ring forgings. In Europe, EN 586 parts 1 to 3 cover forgings. Aerospace orders often call an SAE AMS material specification plus ultrasonic inspection to AMS-STD-2154.
Can rings be supplied machined?
Yes. Rings can be supplied as rolled, rough machined to a sonic shape for ultrasonic inspection, or finish machined to your drawing. State the supply condition and any machining allowance on your enquiry.
Why does a ring go out of round after machining?
Quenching after solution heat treatment leaves residual stress. When material is removed, the stress rebalances and the ring distorts. Ordering a stress-relieved temper (T652 or T7352) and rough machining before final machining greatly reduces the problem.
Need aluminium rings for your project?
Send the alloy, dimensions, quantity and inspection class. Our team will reply with the recommended forging route, certification and a delivered price.
