What are 3 safety rules for welding?

Many millennia ago, the history of joining metals can be traced back. This is evident in the Bronze and Iron Ages of Europe and the Middle East. Herodotus, an ancient Greek historian, states that Glaucus of Chios was the one who invented iron welding. The Iron pillar of Delhi was constructed using welding. It was erected in Delhi in India in 310 AD. It weighed 5.4 metric tons. There are many energy sources that can be used to weld, including gas flames (chemical), electric arcs (electrical), lasers, electron beams, friction and ultrasound. Although welding is often used in industry, it can also be done in open space, under water and even in outer space. It is dangerous work and you should take precautions to avoid electric shock, vision damage and inhalation poisonous gases and fumes.

GTAW can be used to weld almost any metal, but it is most commonly used to stainless steel or light metals. This is used where quality welds are critical, such as for aircraft, bicycles, and naval applications. Plasma arc welding is a similar process that uses a tungsten-electrod but uses plasma gas for the arc. Because the arc is stronger than the GTAW, transverse control is more important and the technique can only be used in a controlled manner. The method is stable and can be used with a wider variety of material thicknesses than the GTAW process. It also runs much faster. The process can be used on all materials except magnesium. Automated welding of stainless steel is an important application. Plasma cutting, a more efficient method of cutting steel, is another variation.

World War I saw a significant increase in welding. The various military powers tried to decide which of the many new welding processes was best. British used arc welding most often, even building a ship called the "Fullagar", with a completely welded hull. The first time arc welding was used on aircrafts during World War II is when several German plane fuselages were made using the technique. The Maurzyce Bridge, a Polish welded bridge, is also noteworthy (1928). Significant technological advances in welding technology were made during the 1920s. In 1920, automatic welding was introduced. This allowed for continuous feeding of electrode wire. As scientists sought to protect welds against the harmful effects of nitrogen and oxygen in the atmosphere, shielding gas was a hot topic. The main problems were porosity and fragility. There were solutions, including hydrogen, argon and helium, which were used as welding atmospheres. Further advances were made over the next ten years, allowing for the welding and fusion of reactive metals such as aluminum and magnesium. Combining these developments with automatic welding, alternating current and fluxes, there was a significant expansion in arc welding in the 1930s, and later during World War II. The first all-welded merchant vessel, M/S Carolinian was launched in 1930.

Three of the most commonly used crystal lattice structures in metals are the body-centred cubic, face-centred cubic and close-packed hexagonal. Ferritic steel has a body-centred cubic structure and austenitic steel, non-ferrous metals like aluminium, copper and nickel have the face-centred cubic structure. Ductility is an important factor in ensuring the integrity of structures by enabling them to sustain local stress concentrations without fracture. In addition, structures are required to be of an acceptable strength, which is related to a material's yield strength. In general, as the yield strength of a material increases, there is a corresponding reduction in fracture toughness.

Many power supplies are available for providing the electrical power required to arc weld. Two types of power supplies that are most commonly used for welding are constant current power supply and constant voltage power supply. The length of an arc depends on the voltage. Heat input and current are directly related. Constant current power supplies, which can sustain a relatively constant current despite the fluctuating voltage, are commonly used for manual welding processes. This is crucial because manual welding can make it difficult to hold an electrode in a steady position. Therefore, the arc length, and therefore the voltage, will fluctuate. This is why constant voltage power supplies are often used for automated welding processes, including gas metal arc, flux-cored or submerged. Since the current is rapidly changing, any change in the distance between the wires, base material, or wire is quickly corrected. For example, if wire and base material are too closely together, current will rapidly rise, which causes heat to increase and tip of wire melt. It then returns to its original separation distance.