Choosing a magnesium extrusion alloy starts with the profile and the job it has to do. AZ31B is usually the practical place to start for general profiles and parts that still need forming. AZ61A adds strength for suitable bars, tubes, and profiles. AZ80A and ZK60A move toward higher strength, but they can make the extrusion route, die development, and supply conversation more demanding. The drawing, wall layout, temper, and downstream machining matter just as much as the grade name.
Start with the extrusion, not the alloy chart
The same part can be easy or difficult to extrude depending on the cross-section. A plain solid bar is one thing. A thin, wide profile with uneven walls is another. Add an internal void, a narrow tongue, or a tight twist requirement and the question changes again.
That is why a material list alone cannot select an alloy. The extruder needs to see where metal has to travel, where it will cool first, and which dimensions actually control the assembly. A generous tolerance on a cosmetic edge is very different from a tight tolerance on a bearing seat or a sealing surface.
AZ31B is often used when the work calls for a general-purpose wrought magnesium alloy and the profile is not being pushed only for maximum strength. It is commonly worth considering for profiles that need a practical manufacturing route, modest secondary work, or later forming.
AZ61A is a common next step when the component needs more strength and begins life as a bar, tube, or extrusion. That extra strength is useful, but it does not erase the limits of a difficult hollow section. A small closed tube with even walls may be sensible. A wide hollow profile with one very thin wall deserves an early die review.
AZ80A and ZK60A belong in the conversation when the load case points that way. They should not be added to a drawing just because their strength figures look better. Higher-strength magnesium extrusions can bring narrower processing windows, lower elongation in some conditions, and more sourcing questions. The project may still need them. It should be an intentional choice.
For general product forms, composition, and supply information, see our AZ31B magnesium alloy guide, AZ61A magnesium alloy guide, and magnesium extrusion capabilities.
Published strength data needs a product form beside it
The figures below are specified minimums from ASTM B107/B107M-13(2021), not a promise for every section a mill can make. They are useful because they show why temper and product form need to sit beside the alloy name on a drawing. The AZ31B and AZ61A entries are different shapes and sizes from the AZ80A and ZK60A entries.
| Alloy and condition | Form and size basis in ASTM B107 | Tensile strength, min. | Yield strength, min. | Elongation, min. |
|---|---|---|---|---|
| AZ31B-F | Hollow profile, all sizes | 220 MPa | 110 MPa | 8% |
| AZ61A-F | Solid bar, rod, or profile; 6.30–60.00 mm | 275 MPa | 165 MPa | 9% |
| AZ80A-T5 | Solid bar, rod, or profile; 6.30–60.00 mm | 330 MPa | 230 MPa | 4% |
| ZK60A-T5 | Hollow profile, all sizes | 315 MPa | 260 MPa | 4% |
Those numbers explain the direction of travel, not the full design decision. A customer who needs a hollow profile cannot take the AZ80A solid-profile line as a design allowance. Nor should an engineer compare an as-fabricated AZ61A line with a T5 ZK60A line and treat the difference as alloy chemistry alone.
ASTM B107 covers magnesium extruded bars, rods, profiles, tubes, and wire and separates its tensile requirements by alloy, temper, form, and size. The order should name the applicable specification and temper; the mill certificate and project test requirements settle acceptance. ASTM B107/B107M-13(2021) is a useful reference when the drawing is being prepared.
AZ31B, AZ61A, AZ80A, and ZK60A in a real purchase decision
The quickest way to narrow the list is to decide what the part needs before it is cut or coated. This is not a ranking from best to worst. It is a short purchasing view of where each alloy is usually investigated first.
| Alloy | Relative strength direction | Extrusion practicality | Forms commonly reviewed | Why it is often considered |
|---|---|---|---|---|
| AZ31B | Moderate | Generally more forgiving | Profiles, bars, tubes, sheet | General-purpose wrought magnesium work and profiles where manufacturing latitude matters |
| AZ61A | Medium to high | Moderate | Bars, tubes, profiles | More strength than AZ31B while staying in a commonly specified wrought-alloy family |
| AZ80A | High | More demanding | Bars, profiles, forgings | Strength-led structural work where the section and supply route have been reviewed |
| ZK60A | High | More demanding | Bars, profiles, forgings | Higher mechanical-performance work with a confirmed specification and supplier route |
AZ31B. If the profile is complex, the walls are thin, or later forming is still on the table, AZ31B is often the sensible first review. It is also a practical option for prototype work when the team has not yet proven the final section. Its lower strength level can be perfectly adequate when stiffness, attachment design, and wall placement have been handled well.
AZ61A. This is the natural discussion when AZ31B is not carrying the required load margin and the part is fundamentally an extrusion. It can make sense for tubes, rails, bars, and profiles that need a stronger starting point without jumping immediately to a specialty route. The useful question for the mill is usually whether the actual section can be produced consistently, not whether AZ61A exists in a brochure.
AZ80A. AZ80A is more often a strength-first choice. It can suit a solid or relatively straightforward structural profile where extra strength justifies a more demanding route. It is less attractive when the drawing is full of thin tongues, abrupt wall changes, and last-minute geometry changes. Those features are expensive even before the alloy is selected.
ZK60A. ZK60A may be considered when the performance requirement is genuinely higher and the project can support a closer review of temper, product form, availability, and qualification. It is not a default replacement for AZ31B or AZ61A. On a project with ordinary industrial loads, the extra specification and sourcing effort may not buy anything useful.
If the decision is only between the two middle-ground grades, our AZ31B vs AZ61A magnesium alloy comparison goes into that narrower choice. For finished features after extrusion, the first questions are still tool access, workholding, and how chips will be managed during CNC machining magnesium extrusions.
Profile geometry can change the answer
Solid, semi-hollow, and hollow sections do not ask the same thing of an extrusion die. Hollow sections need the material flow around internal tooling to stay balanced. A heavy wall on one side and a light wall on the other can create uneven flow and cooling. A profile can look clean in CAD and still be a poor candidate for the selected alloy and press.
Wall thickness deserves a closer look than a single minimum number. A thin open fin and a thin wall inside a small closed tube are different manufacturing problems. The radius at a wall transition, the depth of a pocket, and the distance between two narrow features all affect how the metal flows. Keeping walls reasonably consistent usually gives the extruder more room to control the section.
It also helps to separate functional requirements from ordinary stock dimensions. A long rail may need tight straightness only where it meets a guide. A profile may need a flat machining pad but not a precision finish along every exterior face. Putting the hard tolerances only where the assembly needs them can avoid needless straightening, fixturing, and scrap.
Secondary machining should be reviewed early. Magnesium is generally straightforward to cut with a suitable setup, but an extrusion can release stress after material is removed. A thin web may move after a long slot is machined. A profile that needs a deep pocket or a precision bore may be better supplied with extra stock in a specific area than with a globally heavier section.
The surface treatment belongs in the same drawing review. Coating can change finished dimensions and it needs a realistic corrosion plan for the service environment. The supplier needs to know whether the part will be indoors, sealed inside an assembly, exposed to moisture, or used near dissimilar metals.
A real material-selection case: choose the grade the work actually needs
In October 2024, a graduate student at a university in Argentina contacted us while selecting magnesium material for a research paper. The request was not an extrusion job. It was a small AZ31B plate order, 200 × 300 × 2 mm, for laboratory work. That distinction mattered.
The project did not require the higher strength of AZ61A, AZ80A, or ZK60A. After discussing the experiment and the size needed, AZ31B was recommended because it met the stated performance need without moving the student into a higher-cost grade. The customer placed the order after the quotation, and the material was delivered within one week. The customer later gave positive feedback on the product.
Small projects make this point especially clear, but the same habit applies to production profiles. A stronger alloy can sound safer during a first conversation. It is not automatically safer for cost, delivery, extrusion yield, or fabrication. Start with the function, then check the form in which the alloy must be supplied.
Before the drawing is quoted
An extrusion inquiry becomes easier to review when it includes the cross-section, outside dimensions, lengths, alloy and temper if known, wall thicknesses, and the dimensions that truly need control. Add straightness or twist limits only where the assembly depends on them. Mention any CNC work, surface treatment, material certificate, inspection report, and annual volume.
For a new custom profile, it is worth sending the drawing before locking the grade. A supplier can then flag a wall transition, hollow feature, or tolerance that may affect the die and recommend whether AZ31B, AZ61A, AZ80A, or ZK60A is the better starting point for the actual job.
