The SI unit of heat energy is
Watt
Joule
Ohm
Volt
The SI unit of temperature is
Celsius
Fahrenheit
Kelvin
Rankine
Specific heat is defined as
Heat to melt the metal
Heat to boil water
Heat to raise 1 kg of material by 1°C
Heat stored per unit volume
Latent heat of fusion is
Heat to change solid to liquid without temperature rise
Heat to raise temperature by 1°C
Heat to vaporise a liquid
Heat lost by radiation
In welding, preheating is done to
Reduce thermal shock and cracking
Increase porosity
Increase arc length
Change colour of weld
Heat input in welding is calculated as
Voltage × Current × Time
Current ÷ Resistance
Temperature ÷ Time
Resistance × Voltage²
Thermal conductivity is the property to
Conduct heat
Resist heat
Store heat
Reflect heat
If heat input is too high, it may cause
Distortion
Higher strength
Reduced bead size
Less penetration
Interpass temperature is
Temperature between successive weld passes
Preheating temperature
Post-weld temperature
Ambient temperature
Post-weld heat treatment helps in
Relieving residual stresses
Increasing porosity
Colouring the weld bead
Reducing bead width
Melting point is defined as
Temperature at which solid becomes liquid
Temperature at which liquid becomes gas
Temperature where solid expands
Freezing temperature of gas
The unit of specific heat in SI system is
J/kg°C
W/m°C
N/m²°C
J/s°C
The property that resists temperature rise is
Specific heat
Thermal conductivity
Latent heat
Coefficient of expansion
Heat-affected zone (HAZ) is
Area of base metal altered by welding heat
Molten weld pool
Electrode tip
Weld slag
High thermal conductivity materials
Require more heat input
Require less heat input
Cannot be welded
Always crack
Cold cracking is caused by
Hydrogen embrittlement at low temperature
Excessive heat input
Arc blow
Slow cooling
Hot cracking occurs
During solidification of weld metal
After cooling
During preheating
During grinding
The coefficient of thermal expansion measures
Expansion per degree rise in temperature
Heat stored per volume
Time taken to cool
Specific heat capacity
In welding, faster cooling rates can cause
Harder and more brittle welds
Softer welds
Less distortion
Stronger joints always
Annealing after welding is done to
Soften the meta
Harden the metal
Reduce heat input
Change electrode size
Arc welding works on
Electric arc heat
Gas combustion
Induction heat
Friction heat
Arc temperature in welding is
500°C
1500°C
3500–4000°C
10,000°C
Arc is produced between
Electrode and workpiece
Two electrodes
Transformer and rectifier
Cable and clamp
Open Circuit Voltage (OCV) in arc welding is typically
5–10 V
50–100 V
150–200 V
500 V
Arc stability means
Continuous smooth arc
Frequent arc breaks
Long arc length
Low temperature arc
