9. arc energy - heat input
TRANSCRIPT
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ARC ENERGY /
HEAT INPUT
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ARC ENERGY / HEAT INPUT.
WHAT ARE THE FACTORS THAT
INFLUENCE ARC ENERGY /
HEAT INPUT
?
AMPERAGE
VOLTAGE
TRAVEL SPEED
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ARC ENERGY HEAT INPUT.
ARC ENERGY;
The amount of heat generated in the
welding arc per unit length of weld.
Expressed in kilo Joules per millimetre
length of weld (kJ/mm).
Arc energy (kJ/mm)= Volts x Amps
welding speed(mm/s) x 1000
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ARC ENERGY HEAT INPUT.
HEAT INPUT
The energy supplied by the welding arc to
the work piece.
Expressed in terms of;
arc energy x thermal efficiency factor
Thermal efficiency factor is the ratio of
heat energy introduced into the weld to
the electrical energy consumed by the arc.
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ARC ENERGY HEAT INPUT.
Heat inputvalues for various welding
processes can be calculated from the arc
energy by multiplying by the following
thermal efficiency factors;
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ARC ENERGY HEAT INPUT.
Thermal efficiency factor kof welding processes
Process No Process
Factor k
121 Submerged arc welding with wire 1.0
111 Metal-arc welding with covered electrodes
0.8
131 MIG welding
0.8
135 MAG welding
0.8
114 Flux-cored wire metal-arc welding without gas shield
0.8
136 Flux-cored wire metal-arc welding with active gas shield 0.8
137 Flux-cored wire metal-arc welding with inert gas shield 0.8
138 Metal-cored wire metal-arc welding with active gas shield
0.8
139 Metal-cored wire metal-arc welding with inert gas shield 0.8
141 TIG welding 0.6
15 Plasma arc welding
0.6
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Abbreviations and symbols
I Arc welding current (Amps)
k Thermal efficiency Factor
v
Welding Speed (mm/min)
Q Heat Input (kJ/mm )
U Arc Voltage (Volts)
U x I
Q
=
k v
x 10
-3
= kJ/mm
ARC ENERGY HEAT INPUT.
Amp x volts x time x
k
or
Q
= WS (mm/min) x1000
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ARC ENERGY HEAT INPUT.
EXAMPLE.
A MAG weld is made and the following
conditions were recorded;
Arc volts = 24
Welding amperage = 240
Travel speed = 300mm / minute.
What is the arc energy and heat input?
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ARC ENERGY HEAT INPUT.
AE (kJ/mm)= Volts x amps
TS (mm/ sec) x 1000
= 24 x 240
(300/60) x 1000
= 5760
5000
AE = 1.152 or 1.2kJ/mm
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ARC ENERGY HEAT INPUT.
AE (kJ/mm)= Volts x amps x 60 x0.8
TS (mm/ min) x 1000
= 24 x 240 x 60 x 0.8
300 x 1000
= 276480
300000
HI= 0.92kJ/mm
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HEAT INPUT.
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HEAT INPUT.
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Monitoring Heat Input As Required by
BS EN ISO 15614-1:2004
In accordance with EN 1011-1:1998
When impact requirements and/or hardness
requirements are specified, impact test shall be
taken from the weld in the highest heat input
position and hardness tests shall be taken from
the weld in the lowest heat input position in order
to qualify for all positions
MONITORING HEAT INPUT.
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When impact requirements apply, the upper limit of heat
input qualified is 25 greater than that used in welding
the test piece
When hardness requirements apply, the lower limit of
heat input qualified is 25 lower than that used in
welding the test piece
Heat input is calculated in accordance with EN1011-1
If welding procedure tests have been preformed at both
a high and low heat input level, Then all intermediate
heat inputs are also qualified
MONITORING HEAT INPUT.
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WELDING PROCEDURE SPECIFCATION.
QUESTIONS ?