Welding is a process used to join metal parts. It consists of applying an electric current to overheat and melt the metal which, when cooled, remains fixed.
There are different types of welding, the most popular are:
MMA or manual electrode welding
Electric current creates an arc between a consumable coated electrode rod and the base metal of the joint to be soldered. The arc provides the heat necessary to melt the metal and the electrode acts as a filler material for fixation. It is the most used type due to its versatility and application possibilities.
MIG or gas metal arc welding
Electric current creates an arc between a continuous consumable wire and the base metal of the joint to be welded. The welding wire is a wire that is continuously fed with current and functions as a bonding material. In addition, the wire and the metal base are protected from environmental contamination by a gas mixture. In this way, welding is achieved at a higher speed and in difficult positions.
ICT or arc, tungsten, and gas welding
This type of welding uses a non-consumable tungsten electrode to create the electric arc. If required by the base metal, a filler can be used as a filler electrode. The electrode and the metal base are protected by a gas mixture. The result is a high-quality weld but requires some skill to apply.
Protective equipment for welding
Welding work involves being exposed to electric current and heat, you can also suffer burns from contact or splashes. For this reason, it is very important to have adequate protective equipment.
The eyes and face of the welder must be protected by a manual or electronic protection screen. Clothing must be long-sleeved and clean of oils and greases, accompanied by a leather apron, gloves and protective boots that isolate sparks and molten metal debris.
How does it work?
To delve into how a weld works, we will distinguish two types, according to their position between the elements to be joined: at an angle and but with penetration.
The effect of continuity is what is called penetration of the weld, since a certain environment close to the weld of the elements to be joined reaches the melting temperature and then continuity with the weld material itself and with the other element is produced. to join.
For this effect to occur, in fillet welds, the fundamental parameter is the so-called throat width of the weld, which is measured as the distance between the junction of two elements to be joined and the line that joins the ends of the deposited bead. welding. In butt welds, this parameter depends on the bevel with which the end of an element is cut that engages the other, with the space between the elements to be welded being filled with the weld.
Therefore, there will be a minimum width of throat or thickness that ensures that the penetration is correct, since the thermal field has come to produce the fusion in the necessary environment, that is, that the penetration has occurred. But if the throat width is excessive, the amount of heat provided will be too, being able to completely melt the base material to be welded, which weakens it to the point of ending its resistance capacity.
How to inspect welding quality?
X ray test for welding is a common non-destructive testing method. Inspection is the process that consists of verifying, examining and reporting on a welding job, based on standards and codes that govern a weld. These are criteria used to examine the dimensions and discontinuities of any welded joint. It is also important to talk about fabrication drawings and welding symbols. These charts show essential characteristics such as size, length, location based on numerous design calculations that meet the demands of a solder joint.
In an inspection process, the welding inspector must initially know:
- Understanding welding drawings.
- Different designs of welded joints.
- Know the destructive and non-destructive tests that are used in welding.
- The elaboration of welding procedures.
- Know and interpret welding symbols.
- Know and interpret the requirements of codes and standards used in welding.
Radiographic Test (RT) Used to indicate the penetration capacity as well as in x ray welds and Gamma Rays. Before some internal change within a material, we can determine with this test, measuring the incident radiation versus the radiation released through an x-ray inspection equipment.
Inclusion
In a weld inspection process, we can relate them to sizes, dimensions, discontinuities, etc. Discontinuities in the weld refer to imperfections that exist within and / or contiguous to the weld. Performing a weld inspection is necessary to verify the quality of the welded joint. One of the main reasons for an inspection is when a joint is of the appropriate quality for a weld joint.
