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- Aluminium's high thermal conductivity and natural tendency for oxidation require careful preparation and higher heat input to avoid welding defects<\/strong> like warping and porosity.<\/li>\n
- Aluminium welding commonly employs TIG, MIG<\/strong>, and other methods like laser and resistance welding<\/strong>, each offering unique benefits for different applications.<\/li>\n
- Successful aluminium welding necessitates selecting the right filler material, adjusting welding parameters, and using appropriate shielding gas<\/strong> to prevent contamination and achieve durable welds.<\/li>\n <\/ul>\n <\/div>\n \n
The Challenges in Welding Aluminium<\/h2>\n
Welding aluminium is a complex process that requires knowledge, skill, and experience. Understanding the different welding processes<\/a> suitable for aluminium and the challenges and workarounds regarding those methods is paramount for achieving successful welding joints<\/a>.<\/p>\n
Oxidation<\/h3>\n
Aluminium rapidly oxidises when exposed to the atmosphere, forming a thin oxide layer with a higher melting temperature (2072 C\u00b0) than aluminium (660 C\u00b0). Welding through this barrier might burn holes through the workpiece.<\/p>\n
The oxide layer can be dissolved using solvents or acids before welding the workpiece. It can be physically removed through mechanical abrasive techniques through an exclusive stainless steel wire brush or sandblasting<\/a>.<\/p>\n
Porousness<\/h3>\n
Aluminium in its molten state, absorbs high amounts of hydrogen, resulting in tiny voids or bubbles forming in the weld metal. This weakens the structural integrity of the metal, making it vulnerable to failure from pressure and stress.<\/p>\n
Porosity<\/a> is minimised by using clean materials and equipment, removing oil and grease from the metal’s surface, and using a shielding gas to limit contamination.<\/p>\n
Impurities<\/h3>\n
Oil, dirt, air and debris can negatively impact the weld zone, affecting the strength and appearance of the workpiece. These impurities can come from multiple sources, such as the environment, equipment, preparation and storage. Discolouration, graining, corrosion<\/a> and oxidation present signs of impurities in a weld joint.<\/p>\n
Proper storage, equipment maintenance and metal preparation are the steps to take to avoid impurities.<\/p>\n
Thickness<\/h3>\n
![\"Welded](\"https:\/\/fractory.com\/wp-content\/uploads\/2023\/05\/aluminium-rail-car-body.jpg\")
<\/p>\nWorking with aluminium typically involves welding materials with varying thicknesses. Welding through a combination of thin and thick material simultaneously can be tricky. Heat applied to the workpiece might melt through the thin material or not penetrate the thick material enough to create a strong weld joint.<\/p>\n
A thorough understanding of the aluminium grades, welding methods, and techniques is the key to success in effectively welding different aluminium sheet thicknesses. Welders can effectively weld these metals by setting the parameters such as amperage and heat input to optimal levels.<\/p>\n
Hot Cracking<\/h3>\n
High levels of thermal stress can lead to hot cracking or solidification cracking in aluminium welds. It is one of the reasons why aluminium was once deemed unsuitable for arc welding.<\/p>\n
Combining various alloying elements and treating aluminium alloys can drastically improve its mechanical properties<\/a>. (Al-Cu) 2xxx and (Al-Zn) 7xxx grade series are aluminium alloys that can heat-treated.<\/p>\n
Thermal Conductivity<\/h3>\n
The high thermal conductivity of aluminium makes it challenging to penetrate the weld joint successfully, as it absorbs and dissipates heat quickly.<\/p>\n
Adjusting the settings on the welding equipment to higher heat input improves penetration.<\/p>\n
Aluminium Welding Methods<\/h2>\n
Several welding processes are used for aluminium, each having its own strengths and weaknesses. Welders usually choose TIG and MIG welding<\/a>, yet other methods can fill in for a unique, desirable result.<\/p>\n
Factors to consider when choosing the type of welding method are the supply, cost (equipment, filler material, other consumables), weld performance, joint design, repeatability, distortion tolerance, production speed, and safety.<\/p>\n
TIG Welding<\/h3>\n
![\"Welder](\"https:\/\/fractory.com\/wp-content\/uploads\/2023\/05\/TIG-welding-aluminium.jpg\")
<\/p>\nGas tungsten arc welding (GTAW)<\/a> or TIG welding is one of the most common welding techniques for joining aluminium because of its precision and quality. It can operate on AC (alternating current) polarity, offering stability to the arc and wiping off the oxide layer. A TIG welder can consistently generate enough heat to fuse aluminium alloys<\/a>, with the ability to weld both thin and thick sections.<\/p>\n
Inert shielding gas, most commonly argon, is fed to the TIG torch to keep the weld puddle free from contamination. Thus, protecting the sensitive aluminium. When the project requires the use of aluminium filler rods, then series 4xxx aluminium filler metal is the most common choice.<\/p>\n
MIG Welding<\/h3>\n
Gas metal arc welding (GMAW)<\/a> or MIG welding is a great welding technique for thicker aluminium sheets as the heat input is higher than in TIG welding. This welding method is quite similar to the TIG process but instead of a non-consumable tungsten electrode, MIG welding utilises an automatically fed electrode wire. The mechanical wire feeding system offers faster travel speeds from its spool gun. Shielding gases are used to protect the welds from contamination.<\/p>\n
Laser Welding<\/h3>\n
- Aluminium welding commonly employs TIG, MIG<\/strong>, and other methods like laser and resistance welding<\/strong>, each offering unique benefits for different applications.<\/li>\n