What's brazing?

What's Flux-cored Arc Welding?

What's Gas Metal Arc Welding?

What's Gas Tungsten Arc Welding?

What's Shielded Metal Arc Welding?

What's submerged arc-welding?

What's welding?

 

 

Brazing is a joining process whereby a non-ferrous filler metal or alloy is heated to
melting temperature above 450°C (842°F), or, by the traditional definition that has
been used in the United States, above 800°F (425)°C and distributed between two
or more close-fittingparts by capillary action. At its liquid temperature, the molten filler
metal and flux interacts with a thin layer of the base metal, cooling to form an except
-ionally strong, sealed joint due to grainstructure interaction.

 

With certain metals, such as Nitinol (Nickel Titanium) and Niobium, a low temperature
eutectic can form. This leads to the bonding of the two metals at a point that can be
substantially lower than their respective melting temperatures. The brazed joint
becomes a sandwich of different layers, each metallurgically linked to the adjacent
layers. Commonbrazements are about 1/3 as strong as the materials they join
because the metals partially dissolve each other at the interface and usually the grain
structure and joint alloy is uncontrolled.

 

To create high-strength brazes, sometimes a brazement can be annealed, or cooled
at a controlled rate, so that the joint's grain structure and alloying is controlled. It is
also at 1/3 strength because the metal used to braze is usually weaker than the
substrate metal because it melts at a lower temperature, ensuring the substrate does
not melt.

 

 

 

 

Flux-cored arc welding (FCAW) is a semi-automatic or automatic arc welding process.
FCAW requires a continuously-fed consumable tubular electrode containing a flux and
a constant voltage or, less commonly, a constant electric current welding power supply
An externally supplied shielding gas is sometimes used, but often the flux itself is
reliedupon to generate the necessaryprotection from the atmosphere. The process is
widely used in construction because of its high welding speed and portability.

 

FCAW was first developed in the early 1950's as an alternative to shielded metal arc
welding (SMAW). The advantage of FCAW vs. SMAW is that the use of stick electrodes
(like those used in SMAW) wasunnecessary. This helped FCAW to overcome many of

the restrictions associated with SMAW.

 

 

 

Gas metal arc welding (GMAW), sometimes referred to by its subtypes, metal inert gas
(MIG) welding or metal active gas (MAG) welding, is a semi-automatic or automatic arc
welding process in which a continuous and consumable wire electrode and a shield
-ing gas are fed through a welding gun.A constant voltage, direct current power source
is most commonly used with GMAW, but constant currentsystems, as well as altern
-ating current, can be used. There are four primary methods of metal transfer in GMAW
  called globular, short-circuiting, spray, and pulsed-spray, each of which has distinct
propertiesand corresponding advantages and limitations.

 

Originally developed for welding aluminium and other non-ferrous materials in the
1940s, GMAW wassoon applied to steels because it allowed for lower welding time
compared to other welding processes.The cost of inert gas limited its use in steels
until several years later, when the use of semi-inert gases such as carbon dioxide
became common. Further developments during the 1950s and 1960s gave the
process more versatility and as a result, it became a highly used industrial process.
Today, GMAW is commonly used in industries such as the automobile industry, where
it is preferred for its versatility and speed. Unlike welding processes that do not
employ a shielding gas, such as shielded metal arc welding, it is rarely used outdoors
or in other areas of air volatility. A related process, flux cored arc welding, often does
not utilize a shielding gas, instead employing a hollow electrode wire that is filled with
flux on the inside.

 

 

 

 

Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is
an arc welding process that uses a nonconsumable tungsten electrode to produce
the weld. The weld area is protected from atmospheric contamination by a shielding
gas (usually an inert gas such as argon), and a filler metal is normally used, though
some welds, known as autogenous welds, do not require it. A constant-current
welding power supply produces energy which is conducted across the arc through
a column of highly ionized gas and metal vapors known as a plasma.

 

GTAW is most commonly used to weld thin sections of stainless steel and light
metals such as aluminum, magnesium, and copper alloys. The process grants
the operator greater control over the weld than competing procedures such as
shielded metal arc welding and gas metal arc welding, allowing for stronger,
higher quality welds. However, GTAW is comparatively more complex and difficult
to master, and furthermore, it is significantly slower than most other welding
techniques. A related process, plasma arc welding, uses a slightly different
welding torch to create a more focused welding arc and as a result is often
automated.

 

 

 

 

Shielded metal arc welding (SMAW), also known as manual metal arc (MMA)
welding or informally as stick welding, is a manual arc welding process that
uses a consumable electrode coated in flux to lay the weld. An electric current,
in the form of either alternating current or direct current from a welding power
supply,is used to form an electric arc between the electrode and the metals to
be joined. As the weld is laid, the flux coating of the electrode disintegrates,
giving off vapors that serve as a shielding gas and providing a layer of
slag, both of which protect the weld area from atmospheric contamination.

 

Because of the versatility of the process and the simplicity of its equipment
and operation, shielded metal arc welding is one of the world's most popular
welding processes. It dominates other welding processes in the maintenance
and repair industry, and though flux-cored arc welding is growing in popularity,
SMAW continues to be used extensively in the construction of steel structures
and in industrial fabrication. The process is used primarily to weld iron and
steels (including stainless steel) but aluminum, nickel and copper alloys can
also be welded with this method.

 

 

 

 

Submerged arc welding (SAW) is a high-productivity welding method in which
the arc is struck beneath a covering layer of flux. This increases arc quality,
since contaminants in the atmosphere are blocked by the flux. The slag that
forms on the weld generally comes off by itself, and combined with the use
of a continuous wire feed, the weld deposition rate is high. Working conditions
are much improved over other arc welding processes, since the flux hides the
arc and no smoke is produced. The process is commonly used in industry,
especially for large products.[21] Other arc welding processes include atomic
hydrogen welding, carbon arc welding, electroslag welding, electrogas welding,

and stud arc welding.

 

 

 

 

Welding is a fabrication process that joins materials, usually metals or thermo
 -plastics, by causing coalescence. This is often done by melting the workpieces
and adding a filler material to form a pool of molten material (the weld puddle)
that cools to become a strong joint, but sometimes pressureis used in conjunc
-tion with heat, or by itself, to produce the weld. This is in contrast with soldering
and brazing, which involve melting a lower-melting-point material between the
workpieces to forma bond between them, without melting the workpieces.

 

Arc weldingMany different energy sources can be used for welding, including a gas
flame, an electric arc, a laser, an electron beam, friction, and ultrasound. While
often an industrial process, welding can be done in many different environments,
including open air, underwater and in space. Regardless of location, however,
welding remains dangerous, and precautions must be taken to avoid burns,
electric shock, poisonous fumes, and overexposure to ultraviolet light.