Physical metallurgy of alluminium
Wrought Al alloys wrought = rolled, extruded, forged heat treatable non-heat treatable International alloy designation system (IADS) e.g. 1XXX = Al 7XXX = Al-Zn-Mg-(Cu) specific example 7075 : Al-1.5Cu-2.5Mg- 5.5Zn 0.3Mn-0.2Cr-0.5Fe-0.4Si-0.3(Zr+Ti)
Classification of wrought aluminum alloys The first digit indicates the alloy group according to the major alloying element: 1xxx Aluminum 99.0% minimum 2xxx Copper (1.9%...6.8%)%) 3xxx Manganese (0.3%... %...1.5%) %) 4xxx Silicon (3.6%...13.5%) 5xxx Magnesium (0.5%...5.5%)%) 6xxx Magnesium and Silicon (Mg 0.4%... %...1.5%,%, Si 0.2%... %...1.7%)%) 7xxx Zinc (1%...8.2%)%) 8xxx Others
The second digit indicates modification of the alloy or impurity limits Original (basic) alloy is designated by 0 as the second digit. Numbers 1 9 indicate various alloy modifications with slight differences in the compositions. Example: In the alloys of the 1xxx series the second digit indicates modifications in impurity limits: 0 means natural impurity limit, 1 9 indicate special control of one or more impurities or alloying element.
The last two digits identify aluminum alloy or indicate the alloy purity In the alloys of the 1xxx series the last two digits indicate the level of purity of the alloy: 1070 or 1170 mean minimum 99.70 70% of aluminum in the alloys, 1050 or 1250 mean 99.50 50% of aluminum in the alloys, 1100 or 1200 mean minimum 99.00 00% of aluminum in the alloys. In all other groups of aluminum alloys (2xxx through 8xxx) ) the last two digits signify different alloys in the group.
Classification of cast aluminum alloys Each cast aluminum alloy is designated by a four digit number with a decimal point separating the third and the forth digits The first digit indicates the alloy group according to the major alloying element: 1xx.x Aluminum 99.0% minimum 2xx.x Copper (4%... %...4.6%) %) 3xx.x Silicon (5%...17%) with added copper and/or magnesium 4xx.x Silicon (5%...12%) 5xx.x Magnesium (4%...10%) 7xx.x Zinc (6.2%...7.5%)%) 8xx.x Tin 9xx.x Others
The second two digits identify aluminum alloy or indicate the alloy purity. In the alloys of the 1xx.x series the second two digits indicate the level of purity of the alloy they are the same as the two digits to the right of the decimal point in the minimum concentration of aluminum (in percents): 150.0 means minimum 99.50% of aluminum in the alloy, 120.1 means minimum 99.20% of aluminum in the alloy. In all other groups of aluminum alloys (2xx.x through 9xx.x) the second two digits signify different alloys in the group.
The last digit indicates the product form: casting (designated by 0 ) or ingot (designated by 1 or 2 depending on chemical composition limits.) A modification of the original alloy or impurity limits is indicated by a serial letter before the numerical designation. The serial letters are assigned in alphabetical order starting with A but omitting I, O, Q, and X (the letter X is reserved for experimental alloys)
Wrought aluminium alloys
Designations of wrought aluminium alloys Non-heat-treatable alloys 1xxx series (Super-purity and commercial-purity aluminium) 3xxx series (Al-Mn and Al-Mn-Mg alloys) 5xxx series (Al-Mg alloys) 8xxx series (Miscellaneous alloys) Heat-treatable alloys 2xxx series (Al-Cu and Al-Cu-Mg alloys) 6xxx series (Al-Mg-Si alloys) 7xxx series (Al-Zn-Mg and Al-Zn-Mg-Cu alloys)
Basic Aluminum Heat Treatment Designations F As Fabricated - No special control has been performed to the heat treatment or strain hardening after the shaping process such as casting, hot working, or cold working. O Annealed - This is the lowest strength, highest ductility temper H Strain Hardened - (applied to wrought products only) Used for products that have been strengthened by strain hardening, with or without subsequent heat treatment. The designation is followed by two or more numbers as discussed below. W Solution Heat Treated - This is seldom encountered because it is an unstable temper that applies only to alloys that spontaneously age at ambient temperature after heat treatment. T Solution Heat Treated - Used for products that have been strengthened by heat treatment, with or without subsequent strain hardening. The designation is followed by one or more numbers as discussed below
H Temper Strain Hardening Codes H1 - Strain hardened only H2 - Strain hardened and partially annealed H3 - Strain hardened and stabilized H4 - Strain hardened and lacquered or painted. This assumes that thermal affects from the coating process affect the strain hardening; seldom encountered
Heat Treating T Temper Codes T1 - Cooled from an elevated temperature shaping process and naturally aged to a substantially stable condition. T2 - Cooled from an elevated temperature shaping process, cold worked, and naturally aged to a substantially stable condition. T3 - Solution heat treated, cold worked, and naturally aged to a substantially stable condition. T4 - Solution heat treated, and naturally aged to a substantially stable condition. T5 - Cooled from an elevated temperature shaping process then artificially aged. T6 - Solution heat treated then artificially aged. T7 - Solution heat treated then and overaged/stabilized. T8 - Solution heat treated, cold worked, then artificially aged. T9 - Solution heat treated, artificially aged, then cold worked. T10 - Cooled from an elevated temperature shaping process, cold worked, then artificially aged.
Super-purity purity and commercial-purity aluminum (1xxx series) Super-purity purity (SP) aluminium (99.99%) Commercial-purity (CP) aluminum (upto 1% impurities or minor additions) Properties: Low tensile strength (90 MPa in CP 1100) Yield stress of only 7-11 MPa. Applications: Electrical conductors Chemical process equipment Foils Decorative finishes. Fe and Si are always present as impurity and form refined FeAl3, Fe 3 SiAl 12 or Fe 2 Si 2 Al 9 constituents. 1100 sheet Showing fragmented and redistributed constituent due to Mechanical working
Cemical Composition os some 1XXX Al alloys
Solubility of elements in aluminium Mg, Cu, Zn and Si are the most commonly used alloying elements in aluminium. Cr, Mn and Zr are used primarily to form compounds which control grain structure