American Aluminum Extrusions team of competent specialists take your concept and transform it into reality. Ask your question todayCommon Design Mistakes in Aluminum. Background. As a rule, designers of metallic structures have learned to design using steel. When designing with aluminum, however, the engineer must not base the design on prior experiences with steel or any other material. The alloy selection, proper joint design and the choice of an optimal welding process may all be a function of the base material. While aluminum obviously obeys the same laws of mechanics as all other materials, it must be approached differently than steel when welded. Aluminum structures are not necessarily more difficult to design or weld than steel structures, they are just different. Dont Just Choose the Strongest Alloy. Aluminum is often chosen as a structural material for applications in which weight savings are important. Very often, the designer will choose the very strongest alloy available. This is a poor design practice for several reasons. First, the critical design limitation for many structures often is deflection, not strength. In such cases, the modulus of elasticity, not the tensile properties, will govern the design. The modulus of most aluminum alloys, weak and strong alike, is approximately the same one third the modulus of elasticity of steel, so no benefit accrues from using the strongest alloy. Second, and most importantly, many of the strongest aluminum alloys are not weldable using conventional techniques. When we speak about aluminum alloys being weldable or non weldable, we are usually referring to the alloys ability to be welded without hot cracking. Alloys that are extremely susceptible to hot cracking are not considered appropriate for structural load carrying applications, and are generally put in the non weldable category. Hot cracking in aluminum alloys is primarily due to the chemistry of the alloy and the weld bead. For virtually every alloying addition, the cracking sensitivity varies as alloy content increases as shown in Figure 1. Weldable alloys have a composition that falls either well above or well below the maximum cracking sensitivity. In some cases, such as that of 6. The additional silicon or magnesium pushes the solidifying weld metal below the cracking sensitivity level. In other alloys, such as 7. These are considered to be non weldable. Figure 1. Alloys are broken into two groups heat treatable alloys and non heat treatable alloys. Hacking Software For Windows 7 more. A relative assessment of weldability is also given for each of these. The non heat treatable alloys are composed of the 1. XXX, 3. XXX, 4. XXX, and 5. XXX series. It is not possible to strengthen these alloys by heat treatment. They can only be strengthened by cold working also called strain hardening. The 1. XXX alloys, such as 1. They are relatively soft and weak, with good corrosion resistance, and are usually used where high electrical conductivity is required, such as for bus bars or as electrical conductors. They are also used in certain applications that require a high degree of resistance to corrosion. All of these alloys are readily weldable. The 3. XXX series of alloys have various levels of manganese Mn added to strengthen them and improve their response to cold work. They are of moderate strength, have good corrosion resistance, and are readily weldable. Aluminum Extrusion Die Design Software' title='Aluminum Extrusion Die Design Software' />They are used for air conditioning and refrigeration systems, non structural building trim, and other applications. The 4. XXX series of alloys have silicon Si added as an alloying element to reduce the melting point and increase their fluidity in the molten state. These alloys are used for welding and brazing filler materials and for sand and die castings. They are the least crack sensitive of all the aluminum alloys. The 5. XXX series of alloys have magnesium Mg added in order to increase their strength and ability to work harden. They are generally very corrosion resistant and have the highest strengths of any of the non heat treatable alloys. Increasing magnesium content in these alloys results in increasing strength levels. These alloys are commonly available in the form of sheet, plate and strip, and are the most common structural aluminum alloys. They are generally not available as extruded sections, because they are expensive to extrude. They are readily weldable, in most cases, with or without filler metal. However, there is an Al Mg cracking peak at approximately 2. Mg, so care must be used in welding alloys such as 5. It should not be welded autogenously i. Weld filler metal with a high Mg content, such as 5. The heat treatable alloys are contained in the 2. Extrusions. Modern equipment, combined with the experience level of our production people, assures that we produce highquality, close tolerance extrusions with. CopperClad Aluminum Wire Safety History Comments on the history, testing, safety of CopperClad Aluminum electrical wiring. COPPERCLAD ALUMINUM WIRE CONTENTS. When designing with aluminum, the engineer must not base the design on prior experiences with steel or any other material. A proven design that delivers breakthrough results. Despite the fact that control systems and infrared thermometers are commonly used in the aluminum extrusion. Aluminum Extrusion Die Design Software' title='Aluminum Extrusion Die Design Software' />XXX, 6. XXX, and 7. XXX alloy families. The 2. XXX family of alloys are high strength Al Cu alloys used mainly for aerospace applications. Aluminum Extrusion Die Design Software' title='Aluminum Extrusion Die Design Software' />In some environments, they can exhibit poor corrosion resistance. In general, most alloys in this series are considered non weldable. A prime example of a non weldable alloy in this series, which is attractive to designers because of its high strength, is alloy 2. This alloy is commonly used in airframes, where it is almost always riveted. It is extremely crack sensitive and almost impossible to weld successfully using standard techniques. Only two common structural alloys in the 2. XXX series are weldable 2. Alloy 2. 21. 9 is very easily weldable and has been extensively welded in fabricating the external tanks for the U. S. space shuttle. The company EKOSWIAT awarded Melting Technology Presezzi Extrusion division for the design and manufacturing of a new complete aluminium foundry plant. This alloy gets its good weldability because of its higher copper content, approximately 6. A closely related alloy, which is also very weldable, is 2. It was developed for fabrication of armored vehicles. Although there are detailed exceptions to this rule, the designer should probably consider all other alloys in the 2. XXX series to be non weldable. The 6. XXX series of alloys are the alloys probably most often encountered in structural work. They are relatively strong although not as strong as the 2. XXX or 7. XXX series and have good corrosion resistance. They are most often supplied as extrusions. In fact, if the designer specifies an extrusion, it will almost certainly be supplied as a 6. XXX alloy. 6. XXX alloys may also be supplied as sheet, plate and bar, and are the most common heat treatable structural alloys. Although all alloys in this series tend to be crack sensitive, they are all considered weldable and are, in fact, welded every day. However, the correct weld filler metal must be used to eliminate cracking. Additionally, these alloys will usually crack if they are welded either without, or with insufficient, filler metal additions. The 7. XXX alloys are the ones that usually trip designers up. They are the very high strength Al Zn or Al Zn Mg Cu alloys that are often used in aerospace fabrication, and are supplied in the form of sheet, plate, forgings, and bar, as well as extrusions. With the few exceptions noted below, the designer should assume that the 7. XXX alloys are non weldable. The most common of these alloys is 7. In addition, these alloys often suffer from poor corrosion performance in many environments. A few of the 7. XXX series defy the general rule and are weldable. These are alloys 7. Some common uses of these alloys today are bicycle frames and baseball bats, both of which are welded. These alloys are easily welded and can sometimes offer strength advantages in the as welded condition over the 6. XXX and 5. XXX alloys. There is one other exception to the general rule that 2. XXX and 7. XXX alloys are unweldable.