Aluminum 6351 · temper
Aluminum 6351-T4
Properties of the T4 condition, compared with the other 6351 tempers.
Pick when the part must be bent or formed after heat treatment and then aged to T6, or where moderate strength with good ductility is enough.
What is 6351-T4?
6351-T4 is 6351 in the T4 temper — pick when the part must be bent or formed after heat treatment and then aged to T6, or where moderate strength with good ductility is enough. 6351-T4 has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 66% of aluminum grades. Elongation at break is 20% and the elastic modulus is 69 GPa (10 Msi). 6351-T4 has a density of 2.71 g/cm³ (0.0979 lb/in³), heavier than 51% of aluminum grades. It melts at 555°C (1,031 °F).
Advantages
- Ductile — tolerates forming and impact — 20%, better than 89% of aluminum grades
- Forms and bends easily — 65/100, better than 80% of aluminum grades
Limitations
- Limited service temperature — 100°C (212 °F), worse than 91% of aluminum grades
6351-T4 properties
Typical room-temperature values for 6351-T4 — 12 properties are specific to this condition; the rest are grade-level values shared by every 6351 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
6351-T4 has a density of 2.71 g/cm³ (0.0979 lb/in³), heavier than 51% of aluminum grades. It melts at 555°C (1,031 °F).
Mechanical12
6351-T4 has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 66% of aluminum grades. Elongation at break is 20% and the elastic modulus is 69 GPa (10 Msi).
Thermal6
6351-T4 is rated for continuous service to 100°C (212 °F). It conducts heat at 154 W/m·K (89 BTU/hr·ft·°F), better than 68% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
6351-T4 conducts electricity at 40 % IACS, better than 72% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), better than 67% of aluminum grades.
Sustainability4
Producing a kilogram of 6351-T4 takes about 210 MJ of energy and emits 12.5 kg of CO₂ — more than 88% of aluminum grades. Typical recycled content is 30%.
Manufacturability8
6351-T4's machinability is fair (48/100, worse than 67% of aluminum grades); weldability very good (78/100); formability good (65/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 6351 tempers and conditions
6351 is also supplied in 10 other conditions. The full side-by-side table is on the 6351 overview.
- T6Default structural condition: peak strength with acceptable ductility for extruded frames, tubes, brackets and machined parts.285 MPa yield · 95 HB
- T5Press-quenched and aged directly on the extrusion line — cheapest route to near-T6 strength in thin sections with good straightness.260 MPa yield · 90 HB
- T4Pick when the part must be bent or formed after heat treatment and then aged to T6, or where moderate strength with good ductility is enough.150 MPa yield · 65 HB
- T11T1 press-quenched and naturally aged 6351 that has been straightened/stress relieved, giving T1-level strength with tighter straightness and lower residual stress.105 MPa yield · 57 HB
- T1As-extruded 6351 quenched on the press and naturally aged — moderate strength with good ductility and formability before any artificial ageing.100 MPa yield · 55 HB
- OFully softened condition for maximum bending, drawing or severe forming before re-solution treatment and ageing.75 MPa yield · 42 HB
- H111Soft, near-annealed 6351 with only incidental strain hardening from handling/straightening — maximum formability, lowest strength.70 MPa yield · 35 HB
Working with 6351-T4
Is 6351 easy to machine?
Machines well in T5/T6 with sharp polished-flute carbide tools, high speed and flood or MQL lubrication; T4/O tempers are gummy and produce built-up edge.
Can 6351 be welded?
Readily GMAW/GTAW welded with 4043 or 5356 filler, but the HAZ over-ages to roughly T4-level strength — design joints for reduced properties or re-heat-treat and age.
Can 6351 be formed, bent or molded?
Extrudes at moderate press speeds (slower than 6063 owing to Mn and Si); bend in O or T4 and age afterwards, since T6 tolerates only generous bend radii.
What surface finishes work on 6351?
Takes clear and hard anodising well and accepts chromate/chrome-free conversion coating, powder coat and paint; the Mn-bearing structure gives a greyer anodic film than 6063.
6351 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 |
|---|---|---|
| Si | 0.7 – 1.3 | 1 |
| Mg | 0.4 – 0.8 | 0.6 |
| Mngrain-structure control, distinguishes 6351 from 6061 | 0.4 – 0.8 | 0.6 |
| Fe | ≤ 0.5 | 0.25 |
| Cu | ≤ 0.1 | 0.03 |
| Zn | ≤ 0.2 | 0.05 |
| Ti | ≤ 0.2 | 0.02 |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.15 | — |
| Al | balance | — |
6351-T4 — frequently asked
What is 6351-T4 used for?
6351-T4 is typically used for pressure pipe, truck rails and cylinders. In short: pressure-tube extrusion.
What is the yield strength of 6351-T4?
6351-T4 has a typical yield strength of 150 MPa (21.8 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 66% of aluminum grades. Strength varies by condition: see the 11 listed tempers.
Is 6351-T4 easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 67% of aluminum grades). Machines well in T5/T6 with sharp polished-flute carbide tools, high speed and flood or MQL lubrication; T4/O tempers are gummy and produce built-up edge.
Can 6351-T4 be welded?
Yes — weldability is rated very good (78/100). Readily GMAW/GTAW welded with 4043 or 5356 filler, but the HAZ over-ages to roughly T4-level strength — design joints for reduced properties or re-heat-treat and age.
What surface finishes work on 6351-T4?
Takes clear and hard anodising well and accepts chromate/chrome-free conversion coating, powder coat and paint; the Mn-bearing structure gives a greyer anodic film than 6063.
Can 6351-T4 be formed, bent or molded?
Extrudes at moderate press speeds (slower than 6063 owing to Mn and Si); bend in O or T4 and age afterwards, since T6 tolerates only generous bend radii.
What is the maximum service temperature of 6351-T4?
6351-T4 is rated for continuous use to about 100°C (212 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 6351-T4?
Yes — 6351-T4 is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — The Aluminum Association (2018)
- EN 755-2 Aluminium and aluminium alloys — Extruded rod/bar, tube and profiles — Mechanical properties — CEN (2016)
- ASTM B221 Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes — ASTM (2021)
- ASM Handbook Vol. 2: Properties and Selection — Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Handbook Vol. 13B: Corrosion — Materials — 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.