Magnesium Alloy QE21-T6
Temper · default condition
ASTM QE21 · EN MC65220, MgRE2Ag1Zr
T6 = solution heat treated and artificially aged
Standard delivery condition for aerospace sand and investment castings — best combination of strength and 200 °C stability.
Values for the T6 condition
Other QE21 tempers and conditions
QE21 is listed in 3 conditions; see the grade overview at QE21.
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 |
T6DefaultThis page 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-T6?
QE21-T6 is QE21 in the T6 temper — standard delivery condition for aerospace sand and investment castings — best combination of strength and 200 °C stability. QE21-T6 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). QE21-T6 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).
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-T6 properties
Typical room-temperature values for QE21-T6; 13 are specific to this condition. Other listed values are QE21 reference data and may not represent this condition. Bars are the position among magnesium alloy grades.
Physical3
QE21-T6 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-T6 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-T6 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-T6 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-T6 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-T6'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. Confirm any required mill or lot documentation when quoting.
Working with QE21-T6
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.
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.
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 | — |
QE21-T6 — frequently asked
What is QE21-T6 used for?
QE21-T6 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-T6?
QE21-T6 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-T6 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-T6 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-T6?
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-T6 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-T6?
QE21-T6 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.