Stress Corrosion Cracking of High Strength Aluminum Alloys.Mechanical Property Data, 7.Aluminum, Plate T6.Condition, prepared by Battelle Memorial Institute, Columbus Laboratories, Columbus, Ohio, under Contract AF3.Air Force Materials Laboratory, Research and Technology Division, Air Force Systems Command, Wright Patterson Air Force Base, March 1.The Theory Of Stress Corrosion Cracking In Alloys Of Copper' title='The Theory Of Stress Corrosion Cracking In Alloys Of Copper' />Understanding The Alloys Of Aluminum.With the growth of aluminum within the welding fabrication industry, and its acceptance as an excellent alternative to steel for many applications, there are increasing requirements for those involved with developing aluminum projects to become more familiar with this group of materials.To fully understand aluminum,it is advisable to start by becoming acquainted with the aluminum identification designation system, the many aluminum alloys available and their characteristics.The Aluminum Alloy Temper and Designation System In North America, The Aluminum Association Inc.Currently there are over 4.The Theory Of Stress Corrosion Cracking In Alloys Of Copper' title='The Theory Of Stress Corrosion Cracking In Alloys Of Copper' />Aluminum Association.The alloy chemical composition limits for all of these registered alloys are contained in the Aluminum Associations Teal Book entitled International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys and in their Pink Book entitled Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot.These publications can be extremely useful to the welding engineer when developing welding procedures, and when the consideration of chemistry and its association with crack sensitivity is of importance.Aluminum alloys can be categorized into a number of groups based on the particular materials characteristics such as its ability to respond to thermal and mechanical treatment and the primary alloying element added to the aluminum alloy.When we consider the numbering identification system used for aluminum alloys, the above characteristics are identified.The wrought and cast aluminums have different systems of identification.The wrought system is a 4 digit system and the castings having a 3 digit and 1 decimal place system. World Racing 2 Patch Cars Download Game here. Wrought Alloy Designation System We shall first consider the 4 digit wrought aluminum alloy identification system.The first digit Xxxx indicates the principal alloying element, which has been added to the aluminum alloy and is often used to describe the aluminum alloy series, i.The second single digit x.Xxx, if different from 0, indicates a modification of the specific alloy, and the third and fourth digits xx.XX are arbitrary numbers given to identify a specific alloy in the series.Case preparation techniques and reloading for accuracy.Free targets for downloading.Use of Moly Coated Bullets with some test results.Brass forming. A Mini Lathe.Example In alloy 5.The only exception to this alloy numbering system is with the 1xxx series aluminum alloys pure aluminums in which case, the last 2 digits provide the minimum aluminum percentage above 9.Alloy 1. 35. 0 9.WROUGHT ALUMINUM ALLOY DESIGNATION SYSTEMAlloy Series.Principal Alloying Element.Minimum Aluminum.Copper. 3xxx. Manganese.Silicon. 5xxx. Magnesium.Magnesium and Silicon.Zinc. 8xxx. Other Elements Table 1.Cast Alloy Designation The cast alloy designation system is based on a 3 digit plus decimal designation xxx.The first digit Xxx.CAST ALUMINUM ALLOY DESIGNATION SYSTEMAlloy Series.Principal Alloying Element.Aluminum. 2xx. x.Copper. 3xx. x. Silicon Plus Copper andor Magnesium.Silicon. 5xx. x. Magnesium.Unused Series. 7xx.Zinc. 8xx. x. Tin.Other Elements. Table 2.The second and third digits x.XX. x are arbitrary numbers given to identify a specific alloy in the series.The number following the decimal point indicates whether the alloy is a casting.A capital letter prefix indicates a modification to a specific alloy.Example Alloy A3.A Axxx. x indicates a modification of alloy 3.The number 3 A3xx.The 5. 6 in Ax. 56.Axxx. 0 indicates that it is a final shape casting and not an ingot.The Aluminum Temper Designation System If we consider the different series of aluminum alloys, we will see that there are considerable differences in their characteristics and consequent application.The first point to recognize, after understanding the identification system, is that there are two distinctly different types of aluminum within the series mentioned above.These are the Heat Treatable Aluminum alloys those which can gain strength through the addition of heat and the Non Heat Treatable Aluminum alloys.This distinction is particularly important when considering the affects of arc welding on these two types of materials.The 1xxx, 3xxx, and 5xxx series wrought aluminum alloys are non heat treatable and are strain hardenable only.The 2xxx, 6xxx, and 7xxx series wrought aluminum alloys are heat treatable and the 4xxx series consist of both heat treatable and non heat treatable alloys.The 2xx. x, 3xx. x, 4xx.Strain hardening is not generally applied to castings.The heat treatable alloys acquire their optimum mechanical properties through a process of thermal treatment, the most common thermal treatments being Solution Heat Treatment and Artificial Aging.Solution Heat Treatment is the process of heating the alloy to an elevated temperature around 9.Deg. F in order to put the alloying elements or compounds into solution.This is followed by quenching, usually in water, to produce a supersaturated solution at room temperature.Solution heat treatment is usually followed by aging.Aging is the precipitation of a portion of the elements or compounds from a supersaturated solution in order to yield desirable properties.The non heat treatable alloys acquire their optimum mechanical properties through Strain Hardening.Strain hardening is the method of increasing strength through the application of cold working.T6, 6. 06. 3 T4, 5.H3. 2, 5. 08. 3 H1.THE BASIC TEMPER DESIGNATIONSLetter.Meaning. FAs fabricated Applies to products of a forming process in which no special control over thermal or strain hardening conditions is employed.OAnnealed Applies to product which has been heated to produce the lowest strength condition to improve ductility and dimensional stability.HStrain Hardened Applies to products that are strengthened through cold working.The strain hardening may be followed by supplementary thermal treatment, which produces some reduction in strength.The H is always followed by two or more digits see subdivisions of H temper belowWSolution Heat Treated An unstable temper applicable only to alloys which age spontaneously at room temperature after solution heat treatment.TThermally Treated To produce stable tempers other than F, O, or H.Applies to product that has been heat treated, sometimes with supplementary strain hardening, to produce a stable temper.The T is always followed by one or more digits see subdivisions of T temper belowTable 3.Further to the basic temper designation, there are two subdivision categories, one addressing the H Temper Strain Hardening, and the other addressing the T Temper Thermally Treated designation.Subdivisions of H Temper Strain Hardened.The first digit after the H indicates a basic operation H1 Strain Hardened Only.H2 Strain Hardened and Partially Annealed.H3 Strain Hardened and Stabilized.H4 Strain Hardened and Lacquered or Painted.The second digit after the H indicates the degree of strain hardening HX2 Quarter Hard HX4 Half Hard HX6 Three Quarters Hard.HX8 Full Hard HX9 Extra Hard.Subdivisions of T Temper Thermally Treated.T1 Naturally aged after cooling from an elevated temperature shaping process, such as extruding.T2 Cold worked after cooling from an elevated temperature shaping process and then naturally aged.T3 Solution heat treated, cold worked and naturally aged.T4 Solution heat treated and naturally aged.T5 Artificially aged after cooling from an elevated temperature shaping process.T6 Solution heat treated and artificially aged.T7 Solution heat treated and stabilized overaged.T8 Solution heat treated, cold worked and artificially aged.T9 Solution heat treated, artificially aged and cold worked.T1. 0 Cold worked after cooling from an elevated temperature shaping process and then artificially aged.Additional digits indicate stress relief.Examples TX5. 1 or TXX5.Stress relieved by stretching.TX5. 2 or TXX5. 2 Stress relieved by compressing.Aluminum Alloys And Their Characteristics If we consider the seven series of wrought aluminum alloys, we will appreciate their differences and understand their applications and characteristics.Series Alloys non heat treatable with ultimate tensile strength of 1.They are weldable.However, because of their narrow melting range, they require certain considerations in order to produce acceptable welding procedures.
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