Substantially - cutting forces are roughly a quarter of those for mild steel and well below aluminium's, tool life is long, and it takes deep cuts at high spindle speeds without built-up edge. Surface finish is excellent straight from the tool. Most of the cost of machining magnesium is swarf handling rather than cutting time.

AZ31B as the general-purpose grade, AZ61A and AZ80A where higher strength is needed, and ZK60A - a magnesium-zinc-zirconium alloy - at the top of the strength range. AZ80A and ZK60A can be artificially aged for further strength, so the alloy and temper should both be specified.

Cathodic protection of steel in fresh water and soil - hot water cylinders, buried tanks, pipelines and heat exchangers. Magnesium is used rather than zinc where the electrolyte has higher resistivity and zinc's driving voltage is insufficient to protect the structure. The anode is consumed and is a replaceable service item.

Water-based coolant is generally avoided, because water in contact with hot magnesium fines can liberate hydrogen. Dry cutting is common and works well given magnesium's low cutting forces and good thermal conductivity, and mineral-oil-based cutting fluids are used where cooling or chip evacuation is needed.

Extrusion breaks up the coarse as-cast grain structure and aligns the resulting fine grains along the extrusion direction, while also closing porosity. The result is higher strength and better ductility along the length than any cast form, with some directionality that matters for parts loaded across the bar axis.

Round rod across a broad diameter range plus rectangular and square bar, with availability concentrated in AZ31B. Because the metal is light, a given diameter costs less to hold and ship than the aluminium equivalent, but the range of stocked sections is narrower, so checking availability before designing to a size is worthwhile.

For any service environment, yes - bare magnesium corrodes in humid and salt conditions and corrodes sacrificially wherever it touches steel or aluminium. Conversion coating, anodising or paint is applied after machining, and fasteners need isolating washers or sleeves. Anode rod is the deliberate exception, since consumption is its function.