Aluminum 6351-T51
Temper
AA 6351 · UNS A96351 · EN AW-6351, AW 6351
T51 = t5, stress relieved by stretching
Use where T5 strength is wanted but residual stress and distortion during machining must be minimised.
Values for the T51 condition
Other 6351 tempers and conditions
6351 is listed in 11 conditions; see the grade overview at 6351.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Slightly strain hardened | Soft, near-annealed 6351 with only incidental strain hardening from handling/straightening — maximum formability, lowest strength. | 70 | 130 | 22 | 35 HB | 50 % IACS |
Annealed | Fully softened condition for maximum bending, drawing or severe forming before re-solution treatment and ageing. | 75 | 150 | 25 | 42 HB | 50 % IACS |
Cooled from hot working and naturally aged | As-extruded 6351 quenched on the press and naturally aged — moderate strength with good ductility and formability before any artificial ageing. | 100 | 180 | 20 | 55 HB | 44 % IACS |
Cooled from hot working, naturally aged, stress relieved by… | T1 press-quenched and naturally aged 6351 that has been straightened/stress relieved, giving T1-level strength with tighter straightness and lower residual stress. | 105 | 185 | 19 | 57 HB | 44 % IACS |
Solution heat treated and naturally aged | 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. | 150 | 250 | 20 | 65 HB | 40 % IACS |
Cooled from hot working and artificially aged | Press-quenched and aged directly on the extrusion line — cheapest route to near-T6 strength in thin sections with good straightness. | 260 | 295 | 12 | 90 HB | 45 % IACS |
T51This page T5, stress relieved by stretching | Use where T5 strength is wanted but residual stress and distortion during machining must be minimised. | 260 | 295 | 11 | 90 HB | 45 % IACS |
Cooled from hot working, cold worked in the die, artificially aged | Specialised press temper for close-tolerance profiles that receive sizing work in the die before ageing. | 265 | 300 | 10 | 92 HB | 45 % IACS |
Solution heat treated and artificially aged | Default structural condition: peak strength with acceptable ductility for extruded frames, tubes, brackets and machined parts. | 285 | 310 | 14 | 95 HB | 44 % IACS |
Solution treated, stress-relieved by stretching, aged, no further… | Choose for long extruded profiles that will be heavily machined and must stay dimensionally stable. | 285 | 310 | 13 | 95 HB | 44 % IACS |
T6, stress relieved by stretching, minor straightening | Same as T6510 but with a small amount of final straightening allowed; the usual stocked temper for precision bar and tube. | 285 | 310 | 13 | 95 HB | 44 % IACS |
What is 6351-T51?
6351-T51 is 6351 in the T51 temper — use where T5 strength is wanted but residual stress and distortion during machining must be minimised. 6351-T51 has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 295 MPa (42.8 ksi) — stronger than 68% of aluminum grades. Elongation at break is 11% and the elastic modulus is 69 GPa (10 Msi). 6351-T51 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
- Conducts heat well — 180 W/m·K (104 BTU/hr·ft·°F), better than 86% of aluminum grades
- High electrical conductivity — 45 % IACS, better than 86% of aluminum grades
- Tough — resists crack growth — 31 MPa·√m (28.2 ksi·√in), better than 80% of aluminum grades
6351-T51 properties
Typical room-temperature values for 6351-T51; 22 are specific to this condition. Other listed values are 6351 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
6351-T51 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-T51 has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 295 MPa (42.8 ksi) — stronger than 68% of aluminum grades. Elongation at break is 11% and the elastic modulus is 69 GPa (10 Msi).
Thermal6
6351-T51 is rated for continuous service to 150°C (302 °F). It conducts heat at 180 W/m·K (104 BTU/hr·ft·°F), better than 86% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
6351-T51 conducts electricity at 45 % IACS, better than 86% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (63/100), better than 69% of aluminum grades.
Sustainability4
Producing a kilogram of 6351-T51 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-T51's machinability is good (63/100, better than 58% of aluminum grades); weldability very good (78/100); formability fair (44/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 6351-T51
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-T51 — frequently asked
What is 6351-T51 used for?
6351-T51 is typically used for pressure pipe, truck rails and cylinders. In short: pressure-tube extrusion.
What is the yield strength of 6351-T51?
6351-T51 has a typical yield strength of 260 MPa (37.7 ksi) and a tensile strength of 295 MPa (42.8 ksi) — stronger than 68% of aluminum grades. Strength varies by condition: see the 11 listed tempers.
Is 6351-T51 easy to machine?
Reasonably — machinability is rated good (63/100, better than 58% 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-T51 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-T51?
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-T51 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-T51?
6351-T51 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.
Can FabDigit make parts in 6351-T51?
Yes — 6351-T51 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. 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.