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Welding---the joining of two pieces of metal---has been in practice nearly since man began working with metals. There are many examples of early welding from the Bronze and Iron Ages, and the art of blacksmithing is a type of welding that was an important part of the economy in the Middle Ages.
Modern arc welding came into practice in the late 1800s, with discoveries in Russia, America and Britain. The first acetylene torch was used around the 1900s, and major leaps forward were made during both World Wars. During World War I, the British constructed the first ship with an arc welded hull, and advances in automatic welding and alternating current continued the expansion of the use of arc welding during World War II. -
Arc welding is one of the most common types of welding. It uses an electric current that arcs between an electrode and the material that is being welded to melt the materials at the point of the weld. Metals welded in this manner can be susceptible to corrosion if they have been exposed to moisture prior to welding, so caution in handling materials must be used.
Resistance welding is used only when the materials to be welded are very thin---resistance welding is limited to pieces of metal with a maximum thickness of 3mm. Electric current is run through the metals, and the heat generated from the resistance of the current welds the sheets together. Spot resistance welding is often used in car manufacturing.
Oxy-fuel welding is when a torch is used to melt the metals that need to be welded. After the metal is melted, other materials are added to the molten metal to create the weld.
Ultrasonic welding does not involve heating the metals in question. The process is used largely on thin wires, which are vibrated at a high frequency and fused together. -
After a weld has been completed, there is a distinctive pattern left behind. In the center of the area is the weld itself, called the "fusion zone." This marks the place that the filler material was added during the welding process. Outside this fusion zone is the "heat-affected zone." This is the area that was affected by the heat of the material and the process used, and varies based on the properties of the base metal.
The heat-affected zone is the weakest part of the weld. It is susceptible to cracking and breaking due to the stress that the material has already experienced. -
Welding is finding its way into new uses. Hobbyists are using welding for any number of projects from radio-controlled vehicles to decorative tins. The art world is also seeing a number of welders beginning to experiment with a way to turn their craft into artwork.
With recent developments not only in the field of welding but also robotics, there is a movement to save labor and manufacturing costs by making welding much more automated. At first, robotics lacked the technology to realistically hold materials and weld with accuracy, but with recent advancements this has been rapidly approaching.
Also on the horizon are new forms of welding, such as varieties that use laser beams and friction as the energy sources. -
Welding can be a dangerous activity; there are a number of safety issues associated with it. Several of these dangers can be addressed in the proper outfitting of the welder. Those welding should be sure to wear heavy, protective, flame retardant clothes that cover the body entirely. Hair should always be pulled back out of the way, and there should be no loose clothing.
Specialized goggles or a face mask are also required to prevent permanent damage to the retinas from the brightness of the arc as well as the sparks and hot metals. A number of different full face masks or eye protection shields are available specifically for welding, and only these should be used. Shields should be purchased from a reputable manufacturer to guarantee that the protection offered is significant enough.
Welding should be done in extremely well ventilated areas.
