Magnesium Alloy Supply and Machining for Montgomery, AL Automotive Manufacturers

AZ31B is the workhorse wrought grade — 3% aluminum, 1% zinc — supplied as sheet, plate, and extrusion. It bends and forms at warm temperatures (around 230 to 290 C), takes weld well with AZ61 or AZ92 filler, and gives a tensile strength near 260 MPa. Montgomery fabricators use it where formed sheet or extruded profile beats casting, such as brackets and enclosure panels. AZ91D is the dominant die-casting alloy: 9% aluminum, 1% zinc, with tightly controlled iron, nickel, and copper to hold corrosion resistance. It is what most automotive magnesium castings in this region actually are — transmission cases, brackets, covers. Yield strength sits around 160 MPa with good as-cast surface and dimensional repeatability across long production runs. WE43 is the specialty grade for heat and creep resistance, alloyed with yttrium and rare earths. It holds properties up to roughly 250 C, which is why it shows up in aerospace-defense gearbox housings and any underhood or near-driveline application that would soften a conventional Mg-Al alloy. It costs more and has a tighter supplier base, so Montgomery buyers typically reserve WE43 for parts that genuinely need the temperature headroom.

Magnesium machines faster than nearly any structural metal — high cutting speeds, low power draw, and excellent surface finish at modest feed rates. But fine chips and dust ignite, and a magnesium fire cannot be fought with water. Shops doing this work in Montgomery run dry or with mineral-oil coolant (never water-based), keep Class D extinguishers at the machine, and maintain disciplined chip removal so swarf never accumulates. Finishing is where corrosion control happens. Chromate conversion coatings, anodizing (such as the Tagnite or Keronite processes), and powder topcoats are the common routes. For automotive brackets bolted against steel, suppliers add isolation washers or coatings to break the galvanic couple that would otherwise corrode the magnesium at every fastener. Tolerances on machined magnesium are tight and stable thanks to low thermal distortion during cutting. Buyers routinely hold +/- 0.05 mm on machined features, and the material's dimensional stability after machining makes it a strong choice for parts that mate into precision assembly fixtures on the line.

Most Montgomery demand splits into two streams: die-cast components from regional casting houses and machined or formed parts from job shops and the local CNC and fabrication base. ManufacturingBase lets buyers filter for high-pressure die casters running AZ91D, sheet-metal shops working AZ31B, and the handful of suppliers qualified to handle WE43. For production parts feeding an IATF 16949 automotive program, PPAP documentation, capability studies, and traceable melt certs are table stakes. When you request quotes, specify the grade, temper, applicable spec (ASTM B90 for sheet, B94 for die castings), corrosion-protection requirement, and any galvanic-isolation needs — that detail up front prevents the back-and-forth that delays first-article approval.