AZ80A-T5 vs AZ80A-T6 is mainly a question about the route used after forming. Both conditions use artificial aging. T5 is cooled from the elevated fabrication temperature and aged. T6 adds a separate solution heat-treatment and quench before aging. On some AZ80A forgings, T5 can retain equal or better strength because it avoids a second high-temperature cycle that changes the forged structure. T6 still has valid uses, but it should be specified only when the material form, supplier process, and part requirement support it.
T5 and T6 describe two different thermal histories
The temper suffix tells the shop which heat-treatment sequence belongs to the material.
For AZ80A, T5 normally means the material is cooled from an elevated-temperature fabrication process and then artificially aged. In a forging operation, the part may leave the press hot, be cooled in the controlled process, and then enter the aging cycle. The material does not go back through a separate solution-treatment furnace step first.
T6 adds that extra stage. After fabrication and cooling, the part is reheated for solution heat treatment, quenched, and artificially aged. The purpose is to change the dissolved and precipitated phases before final aging. It sounds like a more thorough treatment, and for some alloys or component routes it may be the right one. It also adds time, handling, furnace capacity, quench control, and another opportunity for a thin or open-shaped part to move.
A 2013 study of model AZ80A forgings lays out the distinction clearly: its T5 parts were cooled from the forging process and artificially aged, while T6 parts were air-cooled after forging, reheated for solution treatment, water-quenched, and then aged. The same study found that the reheated AZ80A-T6 specimens could develop less uniform grain size. That finding belongs to the study’s specific forging and heat-treatment conditions, but it is a good reminder that “T6” is not a universal performance upgrade. Read the full forging study.
Check which condition the part standard, mill, or forging supplier actually offers for that product form. A drawing that calls out “AZ80A-T6” without a governing specification can force the supplier to interpret a thermal route that may not match their qualified process.
Forged-part properties depend on the exact route
Property tables can be misleading when they mix an extrusion in one temper with a forging in another. AZ80A is supplied in more than one form, and longitudinal extrusion data cannot stand in for a forged arm, bracket, or machine blank. The useful comparison is between samples made from the same alloy and the same forming route.
The table below comes from the AZ80A model-forging study cited above. The researchers forged material at two temperatures, then tested T5 and T6 conditions. It is real tensile and hardness data, not a generic design minimum. It does show how the answer can change with the actual process.
| AZ80A model-forging condition in the study | Ultimate tensile strength | 0.2% yield strength | Elongation | Hardness after heat treatment |
|---|---|---|---|---|
| Forged at 350°C, T5 | 348 MPa | 285 MPa | 9.6% | 86 HB |
| Forged at 350°C, T6 | 350 MPa | 261 MPa | 9.8% | 79 HB |
| Forged at 400°C, T5 | 366 MPa | 293 MPa | 11.0% | 86 HB |
| Forged at 400°C, T6 | 333 MPa | 241 MPa | 9.4% | 75 HB |
For the 400°C model forgings, the T5 route in that work produced higher tensile and yield strength, higher elongation, and higher hardness than the T6 route. That does not authorize anyone to copy 366 MPa onto a purchase order. The study used its own chemistry, forging geometry, solution-treatment cycle, and aging cycle. It does show why a buyer should ask for the supplier’s certified condition and actual product-form data rather than assuming a temper name tells the entire story.
There are published values that look different because the products are different. A current Luxfer MEL reference for solid AZ80A-T5 extrusions lists 310 MPa minimum ultimate tensile strength, 205 MPa yield strength, and 2% elongation under ASTM B107-13. That is a useful extrusion reference, but it is not the number to use for a forged T6 part.
Reheating can affect straightness, stock allowance, and machining
A final heat-treatment cycle can change how the part sits in a fixture.
Imagine an AZ80A forging with two thin ears, a broad machined pad, and a center bore. The part may look stable after forging. A T6 route adds reheating and quenching. Depending on the geometry and the supplier’s controls, that may change residual stress or make final straightness harder to hold. The fix might be a post-treatment straightening operation, more stock left on a machined face, or a revised machining sequence. None of those are problems if the route is decided early. They become costly when the material is already on the floor.
T5 can be attractive when the forming route and aging process already produce the needed properties. Keeping the material out of a separate solution-treatment cycle can simplify the flow. It can also preserve the structure created during forging, as the study above observed in its AZ80A samples.
That does not mean T5 is automatically the low-risk answer for every geometry. An extrusion may have a supplier-standard T5 offering, while a forged component for another application may need a different approved condition. Straightness, ultrasonic inspection, machining allowance, and final property certification still have to match the job.
Machining should be planned around the final temper. If critical datums are machined before a final high-temperature treatment, the shop needs a clear plan for any movement afterward. Many programs leave stock before thermal work, then establish the final datum faces and bores after the part has stabilized. That is a process choice, not a blanket rule. A small rigid block may be finished early; a long ribbed part may not be so forgiving.
For machining detail after the final condition is set, see our CNC machining AZ80A magnesium article. It covers stable workholding, tool reach, and chip handling for lightweight AZ80A parts.
T5 on an established forging or extrusion route
T5 is often worth considering when the design is based on an established AZ80A extrusion or forging route and the supplier already controls the cooling and aging sequence. It is a common condition for high-strength wrought AZ80A. The material can arrive ready for finish machining after the supplier has completed the required aging and certification.
It can be a good fit for parts where the finished shape is sensitive to another heating cycle: a thin structural forging, a long profile, or a machined blank with enough value in it that avoidable distortion becomes expensive. It can also reduce steps. Fewer handling stages do not guarantee a lower part price, but they are worth checking when the order quantity is high or the schedule is tight.
T5 still needs an exact callout. “AZ80A-T5” should be accompanied by the material standard, product form, inspection requirements, and any property direction that matters. A bar, a hollow extrusion, and a die forging cannot be treated as interchangeable simply because the chemistry and temper letters match.
If the part sees a defined load path, show it. Extruded magnesium properties are often reported along the extrusion direction. A bracket loaded across the grain, or a part that is machined from a profile and then bent into an assembly, may need more engineering review than a simple tensile number suggests.
Review a T6 requirement before release
T6 is reasonable when the governing specification, qualified supplier route, or component program requires it. In some cases, the solution-treatment and aging route may be needed to meet a property, microstructure, or approval requirement. The key is to verify the exact condition against the finished part—not simply to request T6 because it sounds like the higher-grade option.
Before releasing a T6 drawing, ask the supplier how they heat treat that material form, whether they quench it, what straightening or stress-relief steps follow, and which mechanical-property minimums apply. Ask when the final machining occurs. The answers will influence machining allowance, fixture design, lead time, and inspection planning.
Put the information the supplier needs directly on the order or RFQ:
- AZ80A standard, supplied form, and required T5 or T6 condition
- 2D drawing and 3D model, with critical datum faces and areas that cannot move after final machining
- Required tensile-property, hardness, or material-certificate documentation
- Final coating, corrosion environment, mating materials, and inspection requirements
That is enough to start a serious conversation without turning the RFQ into a heat-treatment procedure written by the buyer. The supplier should own the qualified process. The buyer should own the functional requirements and acceptance criteria.
For supply discussions, start with the AZ80A magnesium alloy page. If the part is still choosing between AZ80A and another wrought grade, go back to the AZ80A vs AZ61A comparison before locking in a temper.
