Welding Process

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Questions and Answers

What is welding?

A process of joining two similar or dissimilar metallic components (correct)

A process of cutting two metallic components

A process of coating two metallic components

A process of melting two metallic components

What is autogenous welding process?

A process that does not use filler metal (correct)

A process that uses electric arc

A process that uses filler metal

A process that uses frictional heat

In which year was metal arc welding with bare electrode patented?

1885

1900

1880

1890 (correct)

When was resistance butt welding invented in USA?

1886 Signup and view all the answers

When did oxy-acetylene welding become feasible in Europe?

1903 Signup and view all the answers

When were coated electrodes developed?

1907 Signup and view all the answers

What was the year of the development of Thermit Welding?

1903 Signup and view all the answers

What was the reason for the failure of 'Liberty' ships in 1942?

Welding failure Signup and view all the answers

Which industry was the first to use welding for construction of bridges?

Australian infrastructure Signup and view all the answers

What was the main advantage of welding over riveting in shipbuilding?

Allows for prefabrication Signup and view all the answers

What is one of the main applications of welding in the aerospace industry?

Joining of skin sheets to aircraft bodies Signup and view all the answers

What is one of the benefits of welding in building structures?

Leads to considerable savings in steel and money Signup and view all the answers

What is the primary application of welding in the automotive industry?

Production of automobile components like chassis, body and its structure Signup and view all the answers

In which industry is welding used to join leads of special transistors?

Electronic Industry Signup and view all the answers

What is the primary application of welding in nuclear installations?

Spheres for nuclear reactor Signup and view all the answers

What is the most widely used classification of welding processes?

Fusion welding and pressure welding Signup and view all the answers

What is the application of micro-joining in welding?

Joining of thin wire to wire, foil to foil and foil to wire Signup and view all the answers

What is the primary application of welding in the defence industry?

Joining of components of war equipment Signup and view all the answers

What is the primary factor that determines the required pressure for smooth feeding of wire with minimum deformation?

Material of the wire Signup and view all the answers

What is the primary purpose of the grooves on wire feeding rolls?

To accommodate different wire sizes Signup and view all the answers

What is the primary purpose of welding symbols?

To communicate information about the welding procedure without any ambiguity Signup and view all the answers

What is the typical shielding gas used for welding mild steel?

Carbon dioxide Signup and view all the answers

What is the main characteristic of a butt joint?

The plates are in the same horizontal plane and aligned with a maximum deviation of 50 Signup and view all the answers

What is the purpose of a pressure adjusting screw in GMAW?

To apply required pressure on the electrode wire during its feeding Signup and view all the answers

What is the primary advantage of GMA welding over manual metal arc welding?

It produces high-quality welds without slag removal Signup and view all the answers

What is the primary reason for using different shielding gases for different metals?

To achieve better fluidity of molten metal Signup and view all the answers

What type of weld joint is formed by melting the corners of two plates?

Corner joint Signup and view all the answers

What type of power source is required for GMAW process?

Direct current (DC) flat characteristic power source Signup and view all the answers

What is the primary limitation of GMA welding?

It is costly and less portable Signup and view all the answers

What is the term used for gas metal arc welding when an inert gas such as argon or helium is used as the shielding gas?

MIG (Metal Inert Gas) welding Signup and view all the answers

What is the primary purpose of flux in forge welding?

To mix with the oxide and lower its melting temperature and viscosity Signup and view all the answers

What is the common temperature range for heating the work pieces in forge welding?

50% to 90% of its melting temperature Signup and view all the answers

What is the primary advantage of forge welding?

It produces a strong weld joint Signup and view all the answers

What is the name of the welding process that uses a repeated hammering or high-pressure load to join two plates?

Forge Welding Signup and view all the answers

What is the common application of forge welding in cookware?

Manufacturing pots Signup and view all the answers

What is the role of the blacksmith hammer in forge welding?

To create a joint through manual hammering Signup and view all the answers

What is the primary requirement for forge welding?

Clean interface surface Signup and view all the answers

What is the name of the welding process that uses an electric arc to melt the metal?

Shielded Metal Arc Welding (SMA) Signup and view all the answers

What was the historical application of forge welding in weaponry?

Making swords Signup and view all the answers

What is the purpose of mechanical hammering in forge welding?

To weld large work pieces Signup and view all the answers

Study Notes

Welding

Welding is the process of joining two metallic components with the application of heat, with or without the application of pressure, and with or without the use of filler metal.
Heat can be obtained by chemical reaction, electric arc, electrical resistance, frictional heat, sound, and light energy.

History of Welding

During the Bronze Age, parts were joined by forge welding to produce tools, weapons, and ornaments.
The first application of welding with a carbon electrode was developed in 1885.
Metal arc welding with a bare electrode was patented in 1890.
Resistance butt welding was invented in the USA in 1886.
Other resistance welding processes such as spot and flash welding were developed around 1905.
The production of cheap oxygen in 1902 led to the development of oxy-acetylene welding in Europe in 1903.
The development of coated electrodes in 1907 made manual metal arc welding viable for production and fabrication.

Types of Welding

Thermit welding (1903)
Cellulosic electrodes (1918)
Arc stud welding (1918)
Seam welding of tubes (1922)
Mechanical flash welder for joining rails (1924)
Extruded coating for MMAW electrodes (1926)
Submerged arc welding (1935)
Air arc gouging (1939)
Inert gas tungsten arc (TIG) welding (1941)
Iron powder electrodes with high recovery (1944)
Inert gas metal arc (MIG) welding (1948)
Electro slag welding (1951)
Flux cored wire with CO2 shielding (1954)
Electron beam welding (1954)
Constricted arc (plasma) for cutting (1955)
Friction welding (1956)
Plasma arc welding (1957)
Electro gas welding (1957)
Short circuit transfer for low current, low voltage welding with CO2 shielding (1957)
Vacuum diffusion welding (1959)
Explosive welding (1960)
Laser beam welding (1961)
High-power CO2 laser beam welding (1964)

Applications of Welding

Fabrication of pressure vessels, bridges, building structures, aircraft, and space crafts
Shipbuilding, automobile, electrical, electronic, and defense industries
Laying of pipelines and railway tracks
Nuclear installations
Construction of transport tankers, welded tubes, and pipes
Steel furniture, gates, doors, and other items
Micro-joining (junctions of thermocouples, strain gauges to wire leads, etc.)

Classification of Welding Processes

Welding with or without filler material
Source of energy of welding
Arc and non-arc welding
Fusion and pressure welding
Fusion welding (molten metal solidifies freely)
Pressure welding (molten metal, if any, is retained in a confined space under pressure)

Welding Symbols

Symbols used to show the type of weld to be made
Symbols used to show not only the type of weld but also relevant aspects related to welding (size, location, welding process, edge preparation, bead geometry, etc.)

Types of Weld Joints

Butt joint (plates in the same horizontal plane, aligned with a maximum deviation of 50)
Lap joint (plates overlapping each other, with the overlap on one or both sides)
Corner joint (joint made by melting the corners of two plates, approximately perpendicular to each other)
Edge joint (joint made by melting the edges of two plates, almost parallel)
T joint (one plate approximately perpendicular to another plate)

Types of Welds

Groove weld
Fillet weld
Plug weld
Bead on plate weld

Gas Metal Arc Welding (GMAW)

Process in which an arc is struck between a bare wire electrode and the workpiece
Arc is shielded by a shielding gas (inert or active)
Electrode wire is fed continuously through a contact tube
Power source is a direct current (DC) flat characteristic
Electrode wire is connected to the positive terminal of the power source
Shielding gases used: argon, helium, CO2, and mixtures
Wire feeding system: pressure adjusting screw, wire feeding rolls, and grooves

Arc Welding Process

Applies heat generated by an electric arc to melt the faying surfaces of the base metal
Common arc welding processes: manual metal or shielded metal arc welding (MMA or SMA), metal inert gas arc (MIG), tungsten inert gas (TIG), submerged arc (SA), plasma arc (PA), and carbon arc (CA)

Forge Welding

A solid-state welding process in which both plates are heated below their melting temperature
Plastic deformation occurs, and inter-molecular diffusion takes place at the interface surface
Requires a clean interface surface, free from oxide or other contaminant particles
Flux is used to prevent oxidation and to flow out the oxide layer during heating and hammering

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Description

Learn about the process of welding, including the application of heat and pressure to join metallic components. Discover the different sources of heat and the concept of autogenous welding.