welding Flashcards
What is flux, what does it do
substance that prevents. dissolves and facilitates removal of oxide formation and other contaminants in welding
three benefits of flux
1) provides protective atmosphere for welding
2) stabilizes arc
3) reduces spattering
What is the consumable in Gas Metal Arc Welding?
electrode (bare metal wire) with shielding by flooding the arc with an inert gas (i.e. MIG welding)
what’s meant by a consumable
materials used up and need to be regularly replaced during welding, essential to create weld joint and protect weld area
components of gas metal arc welding
a liner, contact tip, gas nozzle, and diffuser.
These parts feed the filler wire, maintain the gas shield, and create a good welding arc
2 types of joining
welding
soldering
adhesive bonding
what does a joining process entail
forming permanent joints between parts
what’s an assembly
mechanical fastening parts together
2 major categories of welding
fusion and solid-state
what’s solid-state welding
uses pressure or combination of heat and pressure
when heat is used in solid state welding, temperature is {1} the welded metal’s melting point
1: below
True of False:
Filler metal is added to solid state welding
False
what’s fusion wleding
Heating two or more materials to their melting point or above, fuse together, strong permanent bond
An example of fusion welding
arc welding
resistance welding
oxyfuel gas welding
describe the process of arc welding
melting two metals together using electricity to create intense heat.
heat produced by an electric arc formed between the workpiece and an electrode.
describe oxyfuel welding
process using high-heat, high-temperature flame produced by burning a fuel gas (most commonly acetylene) mixed with pure oxygen
flame type used in oxyfuel welding
neutral flame
how is friction welding achieved
rotating part in contact with stationary part, generates friction, until rotation stops; axial pressure applied, weld created
what kinds of welding defects can occur?
incomplete/lacking penetration weld and concave beads; leads to cracking
A concave bead is a type of { 1 } that has a depressed/ {2} center, giving it a concave shape. This profile is achieved by controlling the {3} input, often by reducing the voltage or current, or using a smaller {4}. Concave beads are known for providing excellent {5} into the base metal, making them useful for welding {6} materials. However, they can be more challenging to control and are generally not as {7} as convex beads.
1: welding bead
2: indented
3: heat
4:electrode
5: penetration
6: thin
7: strong
In arc welding, a pool of { 1 } is formed near electrode tip, as the electrode is moved along the joint, { 2 } pool {3} in its wake.
1: molten metal
2:molten weld
3: solidifies
consumable meaning
consumed during welding process
what’s a nonconsumable, give an example
not consumed during welding process, e.g. Tungsten
True or False:
In Arc welding, filler metal must not be separately added
False
In arc welding, at high temperatures, metals are chemically reactive to { 1.0,1.1 ,1.2 } in the air. These reactions cause {2} properties of the joint to {3}.
1: oxygen, nitrogen, hydrogen
2: mechanical
3: degrade
purpose of arc shielding
to protect the operation by shielding arc from surrounding air
2 shielding gases used in arc shielding, and the other component:
Argon, Helium, CO2
flux
what’s a flux? (in context of arc shielding)
substance preventing, dissolving, and facilitating removal of, oxide formation (and other contaminants) in welding
what does a flux do
provides protective atmosphere for welding, stabilizes arc, reduces spattering
give an application of a flux
1) stick electrode coated with flux material that melts during welding to cover operation
2) tubular electrodes in which flux is contained in the core, and released as electrode consumed
2 consumable electrode arc welding processes…
flux cored arc welding
shielded metal arc welding
gas metal arc welding
what does shield metal arc welding use
consumable electrode, consisting of filler metal rod coated with chemicals to provide flux and shielding
In shield metal arc welding, for the welding stick, the composition of the filler metal is close to the { 1 }. The coating is { 2 } mixed with {3} and {4}, held together by a silicate {5}
1: base metal
2: powdered cellulose
3, 4: oxides, carbonates
5: binder
2 disadvantages of stick welding
1: sticks must be periodically changed
2: high current levels may prematurely melt coating
applications of smaw (steel metal arc welding)
used for steels, stainless steels, cast irons, some nonferrous alloys
