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Aluminium 5251


Aluminium alloy 5251 is a medium strength alloy with good ductility and good formability. Alloy 5251 is known for work hardening rapidly and is readily weldable. It has a high corrosion resistance particularly in marine environments.


This material is used for containers, durniture tubing, marine structures, boats, panelling and pressings, aircraft parts, silos and vehicle panels.

Supplied Forms

  • Sheet
  • Plate

Temper Types

The most common tempers for 5251 aluminium are:

  • H24 - Work hardened by rolling then annealed to half hard
  • H26 - Work hardened by rolling then annealed to three quarter hard
  • H22 - Work hardened by rolling then annealed to quarter hard
  • O - Soft.


  • Weldability - Gas: Very Good
  • Weldability - Arc: Very Good
  • Weldability - Resistance: Very Good
  • Brazability: Poor
  • Workability - Cold: Very Good
  • Machinability: Average


Aluminium alloy 5251 is a readily weldable alloy. The recommended filer wire is 5356 when welding alloy 5251 to itself, 6XXX series alloys, 7XXX series alloys and most other 5XXX series alloys. When welding alloy 5251 to 5005, 5020, 1XXX series or 3XXX series alloys, the recommended filler wire is 4043.

Chemical Compositions

Element % Present
Manganese (Mn) 0.1 - 0.50
Iron (Fe) 0.50 Typical
Copper (Cu) 0.15 Typical
Magnesium (Mg) 1.7 - 2.40
Silicon (Si) 0.40 Typical
Zinc (Zn) 0.15 Typical
Chromium (Cr) 0.15 Typical
Titanium (Ti) 0.15 Typical
Aluminium (Al) Balance

Mechanical properties at room temperature

Property Value
Proof Strength 165 MPa
Tensile Strength 210 MPa
Elongation 14%
Shear Strength 125 MPa
Hardness Vickers 65 HV
Properties above are for material in the H22 condition

Reference data for some physical properties (for guidance only)

Property Value
Density 2.69 Kg/m3
Melting Point 625 °C
Thermal Expansion 25 x 10-6 /K
Modulus of Elasticity 70 GPa
Thermal Conductivity 134W/m.K
Electrical Resistivity 0.044 x 10-6 Ω .m


thyssenkrupp Materials (UK) Ltd
Cox’s Lane
Cradley Heath
West Midlands
B64 5QU

Important Note

Information given in this data sheet about the condition or usability of materials respectively products are no warranty for their properties, but act as a description. The information, we give on for advice, comply to the experiences of the manufacturer as well as our own. We cannot give warranty for the results of processing and application of the products.

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