17-03-2014, 03:40 PM
WELDING HISTORY & PROCESS
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WELDING
Welding is a materials joining process which produces coalescence of materials by heating them to suitable temperatures with or without the application of pressure or by the application of pressure alone, and with or without the use of filler material.
Welding is used for making permanent joints.
It is used in the manufacture of automobile bodies, aircraft frames, railway wagons, machine frames, structural works, tanks, furniture, boilers, general repair work and ship building.
A Brief History of Welding
Late 19th Century
Scientists/engineers apply advances in electricity to heat and/or join metals (Le Chatelier, Joule, etc.)
Early 20th Century
Prior to WWI welding was not trusted as a method to join two metals due to crack issues
1930’s and 40’s
Industrial welding gains acceptance and is used extensively in the war effort to build tanks, aircraft, ships, etc.
Modern Welding
the nuclear/space age helps bring welding from an art to a science
Weldability of a Metal
Metallurgical Capacity
Parent metal will join with the weld metal without formation of deleterious constituents or alloys
Mechanical Soundness
Joint will be free from discontinuities, gas porosity, shrinkage, slag, or cracks
Servicbilieaty
Weld is able to perform under varying conditions or service (e.g., extreme temperatures, corrosive environments, fatigue, high pressures, etc.)
Weld Metal Protection
During fusion welding, the molten metal in the weld “puddle” is susceptible to oxidation
Must protect weld puddle (arc pool) from the atmosphere
Methods
Weld Fluxes
Inert Gases
Vacuum
Arc welding
Equipments:
A welding generator (D.C.) or Transformer (A.C.)
Two cables- one for work and one for electrode
Electrode holder
Electrode
Protective shield
Gloves
Wire brush
Chipping hammer
Goggles
GAS WELDING
Sound weld is obtained by selecting proper size of flame, filler material and method of moving torch
The temperature generated during the process is 33000c
When the metal is fused, oxygen from the atmosphere and the torch combines with molten metal and forms oxides, results defective weld
Fluxes are added to the welded metal to remove oxides
Common fluxes used are made of sodium, potassium. Lithium and borax.
Flux can be applied as paste, powder,liquid.solid coating or gas.
[attachment=60140]
WELDING
Welding is a materials joining process which produces coalescence of materials by heating them to suitable temperatures with or without the application of pressure or by the application of pressure alone, and with or without the use of filler material.
Welding is used for making permanent joints.
It is used in the manufacture of automobile bodies, aircraft frames, railway wagons, machine frames, structural works, tanks, furniture, boilers, general repair work and ship building.
A Brief History of Welding
Late 19th Century
Scientists/engineers apply advances in electricity to heat and/or join metals (Le Chatelier, Joule, etc.)
Early 20th Century
Prior to WWI welding was not trusted as a method to join two metals due to crack issues
1930’s and 40’s
Industrial welding gains acceptance and is used extensively in the war effort to build tanks, aircraft, ships, etc.
Modern Welding
the nuclear/space age helps bring welding from an art to a science
Weldability of a Metal
Metallurgical Capacity
Parent metal will join with the weld metal without formation of deleterious constituents or alloys
Mechanical Soundness
Joint will be free from discontinuities, gas porosity, shrinkage, slag, or cracks
Servicbilieaty
Weld is able to perform under varying conditions or service (e.g., extreme temperatures, corrosive environments, fatigue, high pressures, etc.)
Weld Metal Protection
During fusion welding, the molten metal in the weld “puddle” is susceptible to oxidation
Must protect weld puddle (arc pool) from the atmosphere
Methods
Weld Fluxes
Inert Gases
Vacuum
Arc welding
Equipments:
A welding generator (D.C.) or Transformer (A.C.)
Two cables- one for work and one for electrode
Electrode holder
Electrode
Protective shield
Gloves
Wire brush
Chipping hammer
Goggles
GAS WELDING
Sound weld is obtained by selecting proper size of flame, filler material and method of moving torch
The temperature generated during the process is 33000c
When the metal is fused, oxygen from the atmosphere and the torch combines with molten metal and forms oxides, results defective weld
Fluxes are added to the welded metal to remove oxides
Common fluxes used are made of sodium, potassium. Lithium and borax.
Flux can be applied as paste, powder,liquid.solid coating or gas.