9. Arc Energy - Heat Input

8/10/2019 9. Arc Energy - Heat Input

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Copyright2006,TWILtdorld Centre for Materials Joining Technology

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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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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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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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


Amp x volts x time x

k

or

Q

= WS (mm/min) x1000




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?




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




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



HEAT INPUT.


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orld Centre for Materials Joining Technology

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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orld Centre for Materials Joining Technology

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 ?

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9. Arc Energy - Heat Input