General welding and brazing (brazing) and soft soldering (soldering) the difference between soft brazing melting by lower melting point (below the melting point of workpiece itself) to form solder connection, without heating melting the artifact itself.
There are many sources of energy for welding, including gas flame, arc, laser, electron beam, friction and ultrasonic wave. In addition to being used in factories, welding can be done in a variety of environments, such as fields, underwater and space. No matter where it is, welding may bring danger to the operator, so proper protective measures must be taken in welding. The possible injuries caused by welding include burns, electrocution, visual impairment, inhalation of toxic gases, and excessive exposure to ultraviolet rays.
Welding is the method of heating the workpiece interface to the molten state during the welding process without adding pressure. When welding, the heat source will quickly heat and melt the interface between two workpieces to be welded, forming a molten pool. The molten pool moves forward with the heat source, forming a continuous weld after cooling and connecting the two workpieces together.
During welding, if the atmosphere is in direct contact with the hot pool, the oxygen in the atmosphere oxidizes metals and various alloy elements. When nitrogen and water vapor in the atmosphere enter the molten pool, porosity, slag inclusion and cracks will be formed in the weld during the subsequent cooling process, which will worsen the quality and performance of the weld.
In order to improve the welding quality, various protection methods have been developed. For example, gas arc welding USES gases such as argon and carbon dioxide to insulate the atmosphere, so as to protect the arc from oxidation during welding and avoid the formation of defects. And as steel welding, add affinity for oxygen in covering titanium iron powder of the solid, can protect the electrode in the beneficial elements such as manganese, silicon from oxidation and into the molten pool, cooled to obtain high quality welds.
