Magnesium Alloys

Magnesium is the lightest structural metal: two-thirds the density of aluminum and a quarter of steel, with the best specific stiffness of any common alloy and the best damping. It die-casts thin walls faster than aluminum and machines faster than any other metal — the chips come off dry at very high speed. The price is chemistry: magnesium corrodes galvanically against every other metal, burns as fine chips, and softens above ~120 °C in the common alloys. Used where those limits are managed — laptop shells, camera bodies, steering wheels, aircraft gearbox housings — nothing is lighter.

Magnesium alloys by group

Wrought (extruded, rolled, forged)Mg-Al-Zn, Mg-Zn-Zr, Mg-Mn · AZ31B, AZ61A, AZ80A, ZK60A, M1A2890 – 275Machined plate and bar for prototypes and fixtures, extruded profiles, forged wheels and racing parts — AZ31B is the standard sheet and plate, AZ80 and ZK60 the strong forging grades.

Die & sand casting alloysMg-Al-Zn, Mg-Al-Mn, Mg-Al-Si · AZ91D, AM60B, AM50, AS41B2755 – 245Thin-wall die castings in volume: housings, frames, steering wheels, seat structures. AZ91D for strength and castability; AM60B / AM50 where ductility and crash energy matter; AS41 for creep to 150 °C.

Rare-earth & high-temperature alloysMg + Y, Nd, Gd, Zr · WE43, EV31A (Elektron 21), HK31A15110 – 200Aerospace gearbox and generator housings, motorsport, medical implants — retain strength and creep resistance to 250–300 °C and corrode more slowly than AZ grades.

Choose magnesium for

Die-cast housings, covers and brackets where weight decides the design — consumer electronics, power tools, automotive interiors and seats, drone and camera bodies; machined prototypes of those parts; aircraft and helicopter gearbox and transmission housings (WE43, EV31A); and vibration-sensitive structures that need damping. A magnesium housing weighs 30 % less than the same part in aluminum at similar stiffness.

Look elsewhere when

The part is wet, salty or bolted to steel without insulation (aluminum — magnesium is the anode in every galvanic couple), it runs above 120–150 °C for long periods (2000 series aluminum, or the rare-earth Mg grades to 250 °C), it needs high strength or fatigue life (aluminum 7075, titanium), or it will be welded in the field. Sheet-metal work in magnesium needs warm forming, and fine machining chips are a fire hazard that not every shop is equipped for.

Yield strength against elongation at break, every magnesium alloy grade

No materials in view have both of these properties.

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Magnesium Alloy by application

Lightest possible housings and covers: AZ91D die-cast for volume; AZ31B plate machined for prototypes and low volumes of the same part; AM60B where the housing must not shatter on impact.
Strength and fatigue in wrought parts: ZK60A-T5 for forged wheels, suspension and bicycle parts; AZ80A-T5 as the cheaper forging grade; AZ61A for extrusions that need more than AZ31.
Heat to 250 °C and aerospace castings: WE43-T6 for helicopter gearboxes and race engines; EV31A for sand castings with better castability; AS41B as the low-cost die-cast grade for 150 °C.
Ductility and impact: Steering-wheel armatures, seat frames and instrument-panel beams — 8–10 % elongation versus 3 % for AZ91D.
Better corrosion resistance: High-purity (low Fe, Ni, Cu) versions of AZ91D and AM60B corrode an order of magnitude slower than older grades; WE43 is the best of the structural alloys; every magnesium part still needs a conversion coat and paint outdoors.

FabAgentAI

AI suggestions — verify with an engineer before ordering. Estimates are indicative; the quote page prices your exact geometry.

Manufacturing notes

CNC machining: Magnesium machines faster than aluminum — the fastest of any structural metal — with low cutting forces, excellent surface finish and dry or mineral-oil cutting (never water-based coolant, which generates hydrogen). Chips must be kept coarse, collected and stored dry; fine dust is a fire risk, so we run magnesium on dedicated setups with the right extinguishing media.
Die casting: Hot-chamber die casting of AZ91D and AM60B produces walls down to 0.8 mm at faster cycles than aluminum, with longer die life because magnesium does not solder to the steel. Thixomolding is the alternative for very thin electronic shells.
Sheet and forming: AZ31B sheet forms readily at 200–300 °C and poorly at room temperature (hexagonal crystal structure). Bends need generous radii warm; deep draws are done in heated tooling.
Welding: TIG and MIG with matching filler work well on AZ31 and AZ61 in the shop; friction-stir and laser welding are used for production. Die-cast AZ91 welds poorly; WE43 welds well. Full inert shielding, clean surfaces, and stress relief after welding to prevent cracking.
Finishing: A conversion coat is mandatory: chromate (Dow 7), phosphate-permanganate (chrome-free) or anodic coatings (HAE, Tagnite, Keronite plasma electrolytic oxide) — then powder coat or paint for anything outdoors or bolted to another metal. Insulate every steel fastener with a washer or coating.

Most-quoted magnesium alloy grades

Grade	Group	Yield, MPa	Tensile, MPa	Density, g/cm³	Machinability	Weldability	Best for
AZ31B	Wrought (extruded, rolled, forged)	150	255	1.77	Excellent	Very good	Machined plate, sheet, prototypes
AZ91D	Die & sand casting alloys	160	230	1.81	Excellent	Fair	Die-cast housings in volume
AZ80A	Wrought (extruded, rolled, forged)	250	340	1.8	Excellent	Fair	Forged and extruded structural parts
ZK60A	Wrought (extruded, rolled, forged)	260	340	1.83	Excellent	Poor	Highest-strength wrought magnesium
AM60B	Die & sand casting alloys	130	225	1.8	Excellent	Fair	Ductile, crash-tolerant castings
WE43	Rare-earth & high-temperature alloys	175	260	1.84	Excellent	Very good	Aerospace castings to 250 °C
AZ61A	Wrought (extruded, rolled, forged)	230	310	1.8	Excellent	Very good	Higher-strength magnesium bar
AZ61B	Wrought (extruded, rolled, forged)	230	310	1.8	Excellent	Very good	Higher-strength wrought magnesium
HK31A	Wrought (extruded, rolled, forged)	200	255	1.79	Excellent	Very good	Heat-resistant magnesium plate
AS41B	Die & sand casting alloys	140	215	1.77	Excellent	Fair	High-temp die-cast magnesium

Finishes for magnesium alloy

All 111 finishes

56 of our 111 surface finishes take magnesium alloy: 2 recommended outright, 40 with process care, 14 in limited cases. Each finish opens to its datasheet — thickness, hardness, salt-spray hours, spec codes and the magnesium alloy-specific notes — and the configurator prices it on the grade you pick.

Finish	Group	On magnesium alloy	Thickness, µm	Hardness, HV	Salt spray, h	Cost
Magnesium Chemical Conversion Coating	Anodizing, conversion & passivation	Yes	0.5–5	—	—	$$$
Plasma Electrolytic Oxidation	Anodizing, conversion & passivation	Yes	10–150	700–1,500	—	$$$$
Copper Plating	Plating & metallizing	Limited	5–30	50–250	—	$$
Decorative Nickel-Chrome Plating	Plating & metallizing	Limited	0.3–1	700–1,000	96–500	$$$
Electroless Nickel Plating	Plating & metallizing	Limited	5–75	450–1,000	100–1,000	$$$
Cerakote	Paint, powder & polymer coatings	With care	20–30	—	500–1,000	$$$
Conductive Coating	Paint, powder & polymer coatings	With care	15–50	—	—	$$$
Electrophoretic Coating	Paint, powder & polymer coatings	With care	15–35	—	500–1,000	$$
Bead Blasting	Mechanical finishing & post-processing	With care	0	—	—	$
Brushed Finish	Mechanical finishing & post-processing	With care	0	—	—	$$
Deburring	Mechanical finishing & post-processing	With care	0	—	—	$
Chemical Etching	Marking, decoration & colour	With care	5–100	—	—	$$$
Dot Peen Marking	Marking, decoration & colour	With care	50–500	—	—	$
Electrochemical Etching	Marking, decoration & colour	With care	2–25	—	—	$$

42 more finishes accept magnesium alloy — see the full material × finish matrix →

Magnesium Alloy — frequently asked

How much lighter is magnesium than aluminum?

About 33 %: magnesium alloys are 1.74–1.85 g/cm³ against 2.70 for aluminum and 7.85 for steel. Because a housing is usually sized by stiffness and wall thickness rather than strength, the weight saving on a real part is typically 25–30 % over aluminum and 70 % over steel.

Is magnesium a fire hazard in machining?

Fine chips and dust are; solid parts and coarse chips are not. Magnesium ignites at about 470 °C, so a dull tool or a pile of fine swarf is the risk. Shops handle it with sharp tools, dry or mineral-oil cutting, prompt chip removal and Class D extinguishers. A finished magnesium part will not burn in normal use — the metal is used in aircraft and cars.

Does magnesium corrode?

Faster than aluminum, and it is the anode in every galvanic couple — bolt it bare to steel or aluminum in a wet environment and it dissolves. Modern high-purity alloys (AZ91D, AM60B with controlled Fe, Ni, Cu) are much better than older grades, and WE43 better still. Every production part gets a conversion coating plus paint or powder, and fasteners are insulated.

AZ31B or AZ91D — which is the standard?

AZ91D for die castings (about 90 % of magnesium used) and AZ31B for wrought stock — sheet, plate, extrusions, and therefore for machined prototypes. If you are prototyping a part that will eventually be die-cast in AZ91D, we machine it from AZ31B or AZ80 plate; the properties are close enough for form-fit-function work.

Can magnesium be welded or anodized?

Both. AZ31, AZ61 and WE43 TIG-weld well with matching filler under argon; die-cast AZ91 is harder to weld cleanly. Magnesium anodizing (HAE, Dow 17, Tagnite, plasma electrolytic oxide such as Keronite) produces a hard ceramic layer that is the best base for paint — different chemistry from aluminum anodizing, but the same purpose.