Magnesium Alloy QE21
ASTM QE21 · EN MC65220, MgRE2Ag1Zr
QE21 is a silver-bearing rare-earth magnesium casting alloy (MgRE2Ag1Zr, MC65220) used in the T6 or T6-HIP condition, and is the lower-silver variant of the Mg-Ag-RE-Zr family.
Reference datasheet — QE21 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 T6 condition
QE21 tempers and conditions
QE21 is supplied in 3 conditions, soft to hard. T6 is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Rarely supplied; only for non-structural or dimensionally checked castings before heat treatment. | 100 | 155 | 3 | 55 HB | 22 % IACS |
T6Default Solution heat treated and artificially aged | Standard delivery condition for aerospace sand and investment castings — best combination of strength and 200 °C stability. | 175 | 240 | 3 | 75 HB | 113 W/m·K |
hot isostatically pressed, then solution treated and aged | Choose for fatigue- or fracture-critical aerospace castings where residual microporosity must be closed. | 175 | 250 | 5 | 75 HB | 25 % IACS |
What is QE21?
QE21 is a silver-bearing rare-earth magnesium casting alloy (MgRE2Ag1Zr, MC65220) used in the T6 or T6-HIP condition, and is the lower-silver variant of the Mg-Ag-RE-Zr family. It is specified for aerospace sand, investment and low-pressure castings, giving 175 MPa yield, 240 MPa tensile, 3% elongation, 75 HB and 113 W/m·K with service to about 200 °C. Silver content keeps cost high and availability limited, elongation is only 3%, and protective coating is mandatory. WE54 is the alternative where higher strength and 250 °C service are required. QE21 has a density of 1.81 g/cm³ (0.0654 lb/in³), heavier than 58% of magnesium alloy grades. It melts at 545°C (1,013 °F). QE21 has a yield strength of 175 MPa (25.4 ksi) and a tensile strength of 240 MPa (34.8 ksi) — stronger than 72% of magnesium alloy grades. Elongation at break is 3% and the elastic modulus is 44 GPa (6.38 Msi).
What is QE21 used for?
- aerospace investment castings
- structural brackets
- missile housings
Advantages
- High service temperature — 200°C (392 °F), better than 84% of magnesium alloy grades
Limitations
- Hard to polish — 45/100, worse than 93% of magnesium alloy grades
- Limited ductility — 3%, worse than 85% of magnesium alloy grades
QE21 properties
Typical room-temperature values for QE21-T6; bars are the position among magnesium alloy grades.
Physical3
QE21 has a density of 1.81 g/cm³ (0.0654 lb/in³), heavier than 58% of magnesium alloy grades. It melts at 545°C (1,013 °F).
Mechanical13
QE21 has a yield strength of 175 MPa (25.4 ksi) and a tensile strength of 240 MPa (34.8 ksi) — stronger than 72% of magnesium alloy grades. Elongation at break is 3% and the elastic modulus is 44 GPa (6.38 Msi).
Thermal6
QE21 is rated for continuous service to 200°C (392 °F). It conducts heat at 113 W/m·K (65.3 BTU/hr·ft·°F), better than 74% of magnesium alloy grades. Thermal expansion is 26.7 µm/m·K (14.8 µin/in·°F).
Electrical3
QE21 conducts electricity at 25 % IACS, better than 69% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (25/100), better than 64% of magnesium alloy grades.
Sustainability4
Producing a kilogram of QE21 takes about 300 MJ of energy and emits 28 kg of CO₂ — less than 92% of magnesium alloy grades. Typical recycled content is 25%.
Manufacturability8
QE21's machinability is excellent (92/100, worse than 86% of magnesium alloy grades); weldability very good (70/100); formability not recommended (10/100).
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. QE21 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with QE21
Is QE21 easy to machine?
Cuts extremely easily with sharp, high-rake carbide tools at high speed; run dry or with mineral oil (never water-based coolant), keep chips dry and swarf fire precautions in place.
Can QE21 be welded?
GTAW weld repair of castings is routine using matching Mg-RE-Zr filler with argon shielding; re-solution/re-age locally or fully after major repair to restore T6 properties.
Can QE21 be formed, bent or molded?
Foundry alloy only — sand, investment and low-pressure casting with SF6-free (SO2/HFC) melt protection and flux-free zirconium-refined melts; no cold forming.
QE21 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 |
|---|---|---|
| Aglower silver than QE22 (2.0–3.0 %) | 1 – 2 | 1.5 |
| REneodymium-rich rare-earth (didymium) addition | 1.5 – 3 | 2 |
| Zrgrain refiner | 0.4 – 1 | 0.6 |
| Cusmall intentional/permitted addition in the Ag-RE family | 0 – 0.1 | 0.05 |
| Znimpurity limit | ≤ 0.2 | |
| Feimpurity limit, controls corrosion rate | ≤ 0.01 | |
| Niimpurity limit | ≤ 0.01 | |
| Siimpurity limit | ≤ 0.05 | |
| Mg | balance |
What surface finishes work on QE21?
Always apply chromate-free conversion or anodic coating (Dow 17/HAE/PEO) plus epoxy primer and topcoat; insulate steel and CFRP interfaces to avoid galvanic corrosion.
Equivalent designations
Standards and trade names that resolve to Magnesium Alloy QE21 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- MC65220MgRE2Ag1Zr
How much does QE21 cost?
QE21 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.
QE21 — frequently asked
What is QE21 used for?
QE21 is typically used for aerospace investment castings, structural brackets and missile housings. In short: lower-silver QE22 substitute; T6 aerospace casting alloy; strength to about 200 °C.
What is the yield strength of QE21?
QE21 has a typical yield strength of 175 MPa (25.4 ksi) and a tensile strength of 240 MPa (34.8 ksi) — stronger than 72% of magnesium alloy grades. Strength varies by condition: see the 3 listed tempers.
Is QE21 easy to machine?
Yes — machinability is rated excellent (92/100, worse than 86% of magnesium alloy grades). Cuts extremely easily with sharp, high-rake carbide tools at high speed; run dry or with mineral oil (never water-based coolant), keep chips dry and swarf fire precautions in place.
Can QE21 be welded?
Yes — weldability is rated very good (70/100). GTAW weld repair of castings is routine using matching Mg-RE-Zr filler with argon shielding; re-solution/re-age locally or fully after major repair to restore T6 properties.
What surface finishes work on QE21?
Always apply chromate-free conversion or anodic coating (Dow 17/HAE/PEO) plus epoxy primer and topcoat; insulate steel and CFRP interfaces to avoid galvanic corrosion.
Can QE21 be formed, bent or molded?
Foundry alloy only — sand, investment and low-pressure casting with SF6-free (SO2/HFC) melt protection and flux-free zirconium-refined melts; no cold forming.
What is the maximum service temperature of QE21?
QE21 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between QE21-T6 and QE21-F?
T6 is the default condition — standard delivery condition for aerospace sand and investment castings — best combination of strength and 200 °C stability. F: rarely supplied; only for non-structural or dimensionally checked castings before heat treatment. Yield strength is 175 MPa in T6 versus 100 MPa in F.
How much does QE21 cost?
QE21 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
- ASM Handbook Vol.2: Properties and Selection — Nonferrous Alloys (Magnesium castings) — ASM International (1990)
- ASTM B80 — Magnesium-Alloy Sand Castings — ASTM International (2015)
- ASTM B403 — Magnesium-Alloy Investment Castings — ASTM International (2020)
- Elektron QE22 / EQ21 magnesium casting alloy datasheets — Magnesium Elektron (Luxfer MEL Technologies) (2021)
- ASM Handbook Vol.13B: Corrosion of Magnesium and Magnesium Alloys — ASM International (2005)
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.