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AZ91D Magnesium (Die Cast)

AZ91D is the workhorse magnesium die-casting alloy, with higher aluminum content than AZ31B for better castability. At 1.81 g/cm3 it stays ultralight while delivering 230 MPa tensile. The trade-off is low 3% elongation — typical of a die casting — so it suits rigid thin-wall housings rather than parts that must flex or absorb impact.

How AZ91D Magnesium (Die Cast) machines

Like all magnesium it machines extremely fast with low cutting forces, but the same chip-fire precautions apply: flood coolant, sharp tools, coarse chips, no fine dry dust, and a Class D extinguisher. Die-cast parts usually need only light secondary machining of mating faces and tapped holes, minimizing exposure.

Manufacturing & processing

AZ91D is a die-casting-only alloy in this dataset, optimized for thin-wall, high-volume net-shape production with crisp detail. It fills well and releases cleanly. As-cast corrosion resistance (2.5/5) is modest, so parts typically receive chromate conversion coating, powder coat, or paint for service.

Typical applications

Ideal for thin-wall lightweight housings produced in volume: power-tool and hand-tool bodies, electronics and laptop chassis, automotive brackets and covers, and gearbox or pump housings. Best where the design needs a stiff, light, net-shape enclosure and the tooling cost is justified by production quantity.

When to choose it

Pick AZ91D when you need many lightweight die-cast housings and 3% elongation is acceptable. If the part must be wrought, machined from stock, or formed, use AZ31B instead. If higher ductility or corrosion resistance is required, an aluminum die-casting alloy like A380 is a safer choice.

Suitable surface finishes

Common finishes for AZ91D Magnesium (Die Cast): chromate/Alodine, powder coating. Use the finish selector →

FAQ

Why is AZ91D so much less ductile than AZ31B?
AZ91D is a die casting with higher aluminum content, which improves castability but leaves a coarser as-cast structure, giving roughly 3% elongation versus 15% for wrought AZ31B. It is meant for rigid net-shape housings, not parts that must bend or absorb significant impact.
Can AZ91D be welded?
Repair welding of magnesium die castings is difficult because trapped porosity gas can cause spatter and defects, and the cast structure is less weld-friendly than wrought AZ31B. For joining, fasteners or adhesive bonding are generally preferred over welding AZ91D castings.
Is AZ91D suitable for high-volume production?
Yes. It is specifically a die-casting alloy built for thin-wall, high-volume net-shape parts with good detail and dimensional repeatability. The tooling investment pays off across large runs, where its low density and fast cycle times lower per-part weight and cost.

Property values are typical/nominal for early guidance and vary by temper, grade, supplier and heat treatment. Confirm critical specs against a certified datasheet or with an mfgiq engineer.