LYCOS RETRIEVER 
Welding: Metals
built 638 days ago
Welding processes that use a welding power supply to create an electric arc between an electrode and the base material to melt the metal at the welding point. These can use direct or alternating current and consumable or non-consumable electrodes. The welding region is often protected by inert or semi-inert shielding gas and/or a filler material.
Source:
Like the first welding process, forge welding, some modern welding methods do not involve the melting of the materials being joined. One of the most popular, ultrasonic welding, is used to connect thin sheets or wires made of metal or thermoplastic by vibrating them at high frequency and under high pressure. The equipment and methods involved are similar to that of resistance welding, but instead of electric current, vibration provides energy input. Welding metals with this process does not involve melting the materials; instead, the weld is formed by introducing mechanical vibrations horizontally under pressure. When welding plastics, the materials should have similar melting temperatures, and the vibrations are introduced vertically. Ultrasonic welding is commonly used for making electrical connections out of aluminum or copper, and it is ... a very common polymer welding process.
Source:
Persons planning careers in welding need good manual dexterity, good eyesight, and good eye-hand coordination. They should be able to concentrate on detailed work for long periods of time. Because welding processes differ and are used for a wide variety of purposes, the equipment welder’s use and the skill levels vary. Jobs vary from highly skilled manual welders who can use both gas and electric arc welding equipment, and welders who plan their work from drawings or other specifications to those of unskilled welding machine tenders who simply press a button to start a machine. Skilled welders know the characteristics of different types of metals and can weld in various positions. Welders who construct ships and maintenance welders are examples of skilled welders.
Source:
Resistance welding was ... developed during the final decades of the 19th century, with the first patents going to Elihu Thomson in 1885, who produced further advances over the next 15 years. Thermite welding was invented in 1893, and around that time, another process, oxyfuel welding, became well established. Acetylene was discovered in 1836 by Edmund Davy, but its use was not practical in welding until about 1900, when a suitable blowtorch was developed.[4] At first, oxyfuel welding was one of the more popular welding methods due to its portability and relatively low cost. As the 20th century progressed, however, it fell out of favor for industrial applications. It was largely replaced with arc welding, as metal coverings (known as flux) for the electrode that stabilize the arc and shield the base material from impurities continued to be developed.[5]
Source:
Technological advances have led to better welding techniques and more materials that can be welded. But these advances have ... increased the possible hazards to which a welder can be exposed. Whatever process is used, welding requires a lot of energy to melt or fuse the metals. This release of heat and energy can cause chemical and physical reactions that don't normally happen at room temperature. Whatever process is used, welding requires a lot of energy to melt or fuse the metals. This release of heat and energy can cause chemical and physical reactions that don't normally happen at room temperature.
Source:
Establishing proper welding procedures and adhering to those procedures are critical to produce a high quality weld. On interpass welds, some light discoloration may take place. This slight discoloration should be removed prior to making another pass. Reactive metals such as zirconium and titanium will dissolve their own oxides at temperatures greater than 650°C. If the surface oxide is not removed, the oxygen will be dissolved back into the weld during subsequent passes and cause the weld to be less ductile. This cleaning should consist of brushing with a clean, dedicated stainless steel brush and wiping the area down using an approved solvent with a lint-free rag.
Source:
MORE ABOUT
Metals