Magnesium Alloy MB15
ASTM MB15
MB15 is a rare-earth wrought magnesium alloy of the Mg-RE-Zr type comparable to WE43B, zirconium grain-refined and supplied in F, T5, T6 and forged conditions.
Reference datasheet — MB15 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the T5 condition
MB15 tempers and conditions
MB15 is supplied in 5 conditions, soft to hard. T5 is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
as-forged (die forging, no aging) | As-forged wheels/brackets where fibre flow and toughness matter more than peak strength; typically followed by T5 aging if strength is needed. | 200 | 305 | 15 | 68 HB | 25 % IACS |
As fabricated | Pick for as-extruded bar/profile where the small T5 strength gain is not needed and maximum ductility for later bending is wanted. | 230 | 315 | 13 | 70 HB | 26 % IACS |
forged then artificially aged | Standard delivery state for MB15 die forgings needing higher yield strength with good residual ductility. | 230 | 320 | 13 | 78 HB | 27 % IACS |
T5Default Cooled from hot working and artificially aged | Standard stocked condition for MB15/ZK61M extruded bar, tube and profile — best strength/ductility balance without a separate solution treatment. | 275 | 340 | 11 | 82 HB | 28 % IACS |
Solution heat treated and artificially aged | Used mainly on forgings and heavy sections where solutionizing homogenizes segregation and gives the peak yield strength and hardness. | 285 | 350 | 9 | 88 HB | 29 % IACS |
What is MB15?
MB15 is a rare-earth wrought magnesium alloy of the Mg-RE-Zr type comparable to WE43B, zirconium grain-refined and supplied in F, T5, T6 and forged conditions. It is specified for weight-critical forgings and extrusions needing more strength and better corrosion resistance than AZ-series magnesium: 275 MPa yield, 340 MPa tensile, 11 % elongation, 82 HB, 121 W/m·K and 28 % IACS. Fusion weldability is poor (score 25), cold formability is very limited (score 20) and service is capped near 150 °C. Cost and availability are far worse than MB3, the fallback where strength allows. MB15 has a density of 1.8 g/cm³ (0.065 lb/in³), lighter than 63% of magnesium alloy grades. It melts at 520°C (968 °F). MB15 has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 340 MPa (49.3 ksi) — stronger than 100% of magnesium alloy grades. Elongation at break is 11% and the elastic modulus is 45 GPa (6.53 Msi).
What is MB15 used for?
- Aerospace forged fittings and brackets
- High-performance extruded sections
- Motorsport structural components
- UAV and missile structural fittings
- Machined bar-stock brackets for weight-critical assemblies
- Optics and sensor mounts
Advantages
- High strength — 275 MPa (39.9 ksi), better than 100% of magnesium alloy grades
- High electrical conductivity — 28 % IACS, better than 85% of magnesium alloy grades
- Conducts heat well — 121 W/m·K (69.9 BTU/hr·ft·°F), better than 83% of magnesium alloy grades
Limitations
- Difficult to weld — 25/100, worse than 98% of magnesium alloy grades
MB15 properties
Typical room-temperature values for MB15-T5; bars are the position among magnesium alloy grades.
Physical3
MB15 has a density of 1.8 g/cm³ (0.065 lb/in³), lighter than 63% of magnesium alloy grades. It melts at 520°C (968 °F).
Mechanical14
MB15 has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 340 MPa (49.3 ksi) — stronger than 100% of magnesium alloy grades. Elongation at break is 11% and the elastic modulus is 45 GPa (6.53 Msi).
Thermal6
MB15 is rated for continuous service to 150°C (302 °F). It conducts heat at 121 W/m·K (69.9 BTU/hr·ft·°F), better than 83% of magnesium alloy grades. Thermal expansion is 26 µm/m·K (14.4 µin/in·°F).
Electrical3
MB15 conducts electricity at 28 % IACS, better than 85% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (22/100), worse than 57% of magnesium alloy grades.
Sustainability4
Producing a kilogram of MB15 takes about 320 MJ of energy and emits 32 kg of CO₂ — less than 74% of magnesium alloy grades. Typical recycled content is 15%.
Manufacturability8
MB15's machinability is excellent (95/100, better than 54% of magnesium alloy grades); weldability poor (25/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the magnesium alloy family
Yield strength against density for every magnesium alloy grade FabDigit runs. MB15 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with MB15
Is MB15 easy to machine?
Outstanding machinability — high speeds, sharp positive-rake tools, generous chip clearance; never let fine chips accumulate and never use water-based coolant on dry fine swarf (fire risk), keep class-D extinguishing media at the machine.
Can MB15 be welded?
Poor fusion weldability due to Zn-induced hot cracking; prefer mechanical joining, adhesive bonding or friction stir welding — if TIG is unavoidable use ER-AZ-type or matching filler on light sections and accept property loss.
Can MB15 be formed, bent or molded?
Cold formability is very limited; extrude and forge at 300–400 °C, bend/deep-draw warm at 250–350 °C, and design for the tension–compression yield asymmetry of textured extrusions.
MB15 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Znprimary strengthener (MgZn2 precipitation) | 5 – 6 | 5.5 |
| Zrgrain refiner | 0.3 – 0.9 | 0.6 |
| Alimpurity max | ≤ 0.05 | |
| Mnimpurity max | ≤ 0.1 | |
| Siimpurity max | ≤ 0.05 | |
| Cuimpurity max | ≤ 0.05 | |
| Feimpurity max; raises corrosion rate | ≤ 0.05 | |
| Niimpurity max; strongly cathodic | ≤ 0.01 | |
| Others (each)total ≤0.30 | ≤ 0.05 | |
| Mg | balance |
What surface finishes work on MB15?
Always protect: fluoride/phosphate-permanganate chemical conversion or micro-arc oxidation followed by epoxy primer and topcoat; isolate from steel, brass and carbon fibre with insulating washers/sealant to avoid galvanic pitting.
Equivalent designations
Standards and trade names that resolve to Magnesium Alloy MB15 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- WE43B
How much does MB15 cost?
MB15 is a high-cost magnesium alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
MB15 — frequently asked
What is MB15 used for?
MB15 is typically used for aerospace forged fittings and brackets, high-performance extruded sections, motorsport structural components, UAV and missile structural fittings, machined bar-stock brackets for weight-critical assemblies and optics and sensor mounts. In short: strongest wrought magnesium listed; rare-earth Mg-Zr forging grade; poor fusion weldability.
What is the yield strength of MB15?
MB15 has a typical yield strength of 275 MPa (39.9 ksi) and a tensile strength of 340 MPa (49.3 ksi) — stronger than 100% of magnesium alloy grades. Strength varies by condition: see the 5 listed tempers.
Is MB15 easy to machine?
Yes — machinability is rated excellent (95/100, better than 54% of magnesium alloy grades). Outstanding machinability — high speeds, sharp positive-rake tools, generous chip clearance; never let fine chips accumulate and never use water-based coolant on dry fine swarf (fire risk), keep class-D extinguishing media at the machine.
Can MB15 be welded?
Not readily — weldability is rated poor (25/100). Poor fusion weldability due to Zn-induced hot cracking; prefer mechanical joining, adhesive bonding or friction stir welding — if TIG is unavoidable use ER-AZ-type or matching filler on light sections and accept property loss.
What surface finishes work on MB15?
Always protect: fluoride/phosphate-permanganate chemical conversion or micro-arc oxidation followed by epoxy primer and topcoat; isolate from steel, brass and carbon fibre with insulating washers/sealant to avoid galvanic pitting.
Can MB15 be formed, bent or molded?
Cold formability is very limited; extrude and forge at 300–400 °C, bend/deep-draw warm at 250–350 °C, and design for the tension–compression yield asymmetry of textured extrusions.
What is the maximum service temperature of MB15?
MB15 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between MB15-T5 and MB15-F?
T5 is the default condition — standard stocked condition for MB15/ZK61M extruded bar, tube and profile — best strength/ductility balance without a separate solution treatment. F: pick for as-extruded bar/profile where the small T5 strength gain is not needed and maximum ductility for later bending is wanted. Yield strength is 275 MPa in T5 versus 230 MPa in F.
How much does MB15 cost?
MB15 is a high-cost magnesium alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM B107/B107M Magnesium-Alloy Extruded Bars, Rods, Profiles, Tubes (ZK60A) — ASTM (2013)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys (Magnesium) — ASM International (1990)
- Magnesium and Magnesium Alloys, ASM Specialty Handbook — ASM International (1999)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.