Background

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

Chemical Composition

Table 1. Typical chemical composition for aluminium alloy 5251 Element % Present Cu 0.15% Mg 1.7-2.4% Si 0.4% Fe 0.5% Mn 0.1-0.5% Zn 0.15% Ti 0.15% Cr 0.15% Al Balance

Properties Mechanical Properties Table 2. Typical mechanical properties for aluminium alloy 5251 Temper H22 H24 H26 0 Proof Stress 0.2% (MPa) 165 190 215 80 Tensile Strength (MPa) 210 230 255 180 Shear Strength (MPa) 125 135 145 115 Elongation A5 (%) 14 13 9 26 Hardness Vickers (HV) 65 70 75 46 Physical Properties Table 3. Typical physical properties for aluminium alloy 5251 Property Value Density 2.69 g/cm3 Melting Point 625°C Modulus of Elasticity 70 GPa Electrical Resistivity 0.044x10-6 Ω.m Thermal Conductivity 134 W/m.K Thermal Expansion 25x10-6 /K Alloy Designations Aluminium alloy 5251 also corresponds to the following designations: Al Mg2 Al 2.0Mg 0.3Mn Fabrication Welding Aluminium alloy 5251 is a readily weldable alloy. The recommended filler wire is 5356 when welding alloy 5251 to itself, 6XXX series alloys, 7XXX series alloys and most other 5XXX alloys. When welding alloy 5251 to 5005, 5020, 1XXX series or 3XXX series alloys, the recommended filler wire is 4043. Fabrication Response Table 4. Typical fabrication response for aluminium alloy 5251 Process Rating Workability – Cold Very Good Machinability Average Weldability – Gas Very Good Weldability – Arc Very Good Weldability – Resistance Very Good Brazability Poor Solderability - Temper The common tempers for 5251 are: · H22 - Work hardened and partially annealed to a quarter hard state · H24 - Work hardened and partially annealed to a half hard state · H26 - Work hardened and partially annealed to a three quarter hard state · 0 – Wrought and fully annealed

Applications 5251 is typically used in: · Boats · Panelling and pressings · Marine structures · Aircraft parts · Vehicle panels · Furniture tubing · Silos · Containers