Commercial Grade Magnesium (CP Magnesium) refers to high-purity, unalloyed magnesium metal typically containing ≥ 99.8% Mg. It is produced for industrial, chemical, metallurgical, and sacrificial applications rather than high-strength structural use and represents the base material from which all magnesium alloys are developed.
Chemical Composition (Typical)
| Element | Content (wt %) |
|---|---|
| Magnesium (Mg) | 99.80 – 99.95 |
| Aluminum (Al) | ≤ 0.03 |
| Zinc (Zn) | ≤ 0.02 |
| Manganese (Mn) | ≤ 0.02 |
| Iron (Fe) | ≤ 0.005 |
| Copper (Cu) | ≤ 0.01 |
| Nickel (Ni) | ≤ 0.001 |
| Oxygen (MgO surface) | Trace / controlled |
Note: Fe, Cu, and Ni are tightly controlled because even trace amounts significantly reduce corrosion resistance.
Key Mechanical Properties
| Property | Typical Value |
|---|---|
| Tensile Strength | 90 – 110 MPa |
| Yield Strength | 20 – 35 MPa |
| Elongation | 8 – 15% |
| Elastic Modulus | ~45 GPa |
| Hardness | ~30 HB |
| Fatigue Strength | Low |
Physical Properties
| Property | Value |
|---|---|
| Density | 1.74 g/cm³ |
| Melting Point | 650 °C |
| Boiling Point | 1090 °C |
| Thermal Conductivity | ~160 W/m·K |
| Electrical Conductivity | ~38% IACS |
| Thermal Expansion | ~26 µm/m·K |
| Damping Capacity | Very high |
| Magnetic Behavior | Non-magnetic |
Strengthening & Metallurgical Behavior
Crystal Structure: Hexagonal Close-Packed (HCP)
No precipitation hardening
Very limited work hardening
Strength improvement only via grain refinement or alloying
Corrosion & Oxidation Behavior
Forms a thin MgO surface film but is highly reactive in moist air, chloride environments, and acids. Corrosion rate increases sharply with Fe, Cu, or Ni contamination.
Common protection methods include oil coating, conversion coatings, anodizing, and paint or polymer coatings.
Refining & Processing Properties
Primary production via Pidgeon process or electrolytic MgCl₂ process. Secondary processing includes remelting under protective atmosphere, casting, extrusion, rolling, granulation, and powder production.
Available Forms
Ingots
Billets
Rods & bars
Sheets & plates
Foils
Powder & granules
Sacrificial anode shapes
Custom machined components
Applications
Metallurgical
Alloying base metal, desulfurization, nodular cast iron treatment
Chemical
Reducing agent, Grignard reagent production
Corrosion Protection
Sacrificial anodes for pipelines, water heaters, marine systems
Pyrotechnics & Industrial
Flares, ignition materials, lightweight machined parts
Advantages
✔ Lowest density of all structural metals
✔ High chemical & electrochemical activity
✔ Excellent machinability
✔ High thermal conductivity
✔ Superior vibration damping
✔ Fully recyclable
Limitations
❌ Low mechanical strength
❌ Poor corrosion resistance without protection
❌ Limited room-temperature formability
❌ Fire risk in chips and powders
Why Choose Commercial Grade Magnesium?
Choose commercial magnesium when weight reduction, chemical or electrochemical reactivity, sacrificial protection, and machinability are more important than mechanical strength.