lecture 3 - welding

  • def; the partial melting and fusion of two members. In this processes a filler metal can be used to joining the two metals.

    • AUTOGENOUS; welding without a metal filler

fusion welding process

   -    oxyfuel gas / flame weldding

arc welding

high energy beam

Solid state welding process ; when the welding doesnt have a liquid or molten phase present in the join. Friction welding, resistance welding, cold welding

OXYFUEL GAS

  • a welding processes using a flame produced by a fuel gas combined oxide

  • the Gas mixeture to create this flame changes the ratio of the inner and outer cone. a greater oxygen can be a harmful flame from oxidising metals. if oxygen is too low there will be insufficient comnbustion i.e carburising

    • an Oxidising flame is only good for copper alloys

  • Welding tourch tool (where the oxygen has a valve with a pressure gauge regulator)

  • Filler metals

    • they have a flux to RETARD OXIDISE the surface of the parts. it also helps dissolve and rremove oxides and oother substances aiding the the weldinging(making it stronger)

  • Arc welding process

    • heat from electrical energy involving a consumerbal or non consumerbal elcetrode.

    • it generates 30,000 degrees (much higer than oxyfule gas weilding)

    • when TUNDSTEN gas is used it is suitable fo rthin metals i.e titainium magnesium

      • Polarity and current

        • straight polarity creates a narrow and deeep weild

        • reverse polarity is a wide and shallow wield

        • Ac current is suitable for thick sections of the two members

        • figure 1; Heat input Arc wielding equation

H = heat input, joules

L = length of wield

V = voltage applied

I = current

v = speed

e = efficiency normal is from 75% for shielded metal arc to 90% for gas metal arc wielding

Figure 2

this can be subbed into the equation in figure 1 if you don’t have the length

Plasma Arc welding

  • Plasma is an ioniosed hot gas composed

non- consumerbal

Electrogas Weilding (EGW)

Figure 3: welding joint terminology

Electrodes for arc welding

  • E60XX, E110XX ; the E symbolises that the material is an electrode and the number is the tensile strength 60 is 60,000 psi

  • EXX1X shows it is all directions and if 2 indicates it can act in a flat position

electron beam welding (EBW)

Laser-beam wielding high energy welding