welding processes

Question 1

brazing v soldering?

Answer 1

brazing: filler material above 450deg. more stable joints made than soldering. higher cost than soldering

Question 2

two classes of welding

Answer 2

fusion (melting, mixing, filler material) and solid state (heat/pressure but no melting)

Question 3

butt joint

Answer 3

parts in same plane, joined at edges

Question 4

corner joint

Answer 4

parts form right angle, joined at corner

Question 5

tee joint

Answer 5

like letter T, perpendicular

Question 6

lap joint

Answer 6

two overlapping joints

Question 7

edge joint

Answer 7

parts parallel with at least one edge in common

Question 8

fillet weld

Answer 8

‘fill’ edge of plates made by corner, lap, tee, joints

Question 9

butt/groove welds

Answer 9

requires edge of parts to be shaped into groove for weld penetration (square, bevel, V, U, Y, single/double sided

Question 10

plug/slot welds

Answer 10

attaching flat plates using 1+ holes or slots in top part

Question 11

spot/seam weld

Answer 11

small fused section b/w surfaces

Question 12

types of electrical arc welding

Answer 12

shielded metal arc (SMA). metal inert gas (MIG). submerged arc. tungsten inert gas (TIG).

Question 13

what is electric arc

Answer 13

discharge of electric current across a gap in circuit.

Question 14

steps of electrical arc welding

Answer 14

electrode metal melted. droplets carried across arc and mixed with base metal. mixed molten metal pushed to rear. (higher current, faster deposit)

Question 15

what prevents formation of oxide and nitride

Answer 15

gas forms covering arc and prevents exposure of molten metal to air

Question 16

what is consumable electrode vs non consumable electrode

Answer 16

shielded metal arc welding is consumable. TIG is non consumable

Question 17

ac current method?

Answer 17

arc pulsates rapidly.
large diameter electrodes at maximum current
thick section

Question 18

direct current, straight polarity?

Answer 18

narrow, deep welds. electrode negative, workpiece positive.

Question 19

direct current, reverse polarity?

Answer 19

shallow, wide welds.
electrode positive, workpiece negative.

Question 20

what is sma used in

Answer 20

general construction, shipbuilding, pipelines.

Question 21

what gases does SMA generate

Answer 21

carbon dioxide, water vapour, carbon monoxide, hydrogen

Question 22

gases from mig welding

Answer 22

argon, helium, co2 for steel

Question 23

difference between mig and sma

Answer 23

no slag. wire fed continuously from spool through welding gun

Question 24

submerged arc welding

Answer 24

arc shielded by cover of granular flux, from gopper. no sparks or spatter or radiation

Question 25

TIG welding?

Answer 25

used with and without filler material. no filler ideal for stainless steel.

Question 26

oxyfuel gas welding?

Answer 26

base metal melted with welding torch

Question 27

resistance welding?

Answer 27

fusion welding, combo of heat and pressure. pulsed low voltage, high A current