RELATION BETWEEN WELD CROSS-SECTION AND ENERGY INPUT

Q

h H AEI

where Hnet = —

There is a simple but important relationship between the weld metal cross-section. Aw energy input :

f2 Hnet _ Л f 2 H

A.. =

Q

J/s.

Heat required for melting in Joules/mm3 E = voltage supplied in volts.

I = current consumed in Amp. v = welding speed in mm/s

Aw = (Am + Ar) in mm2

A, = A if no filler metal is added

Q =

and

where Aw = (Am + Ar)

f1 = heat transfer efficiency from electrode to plate f2 = melting efficiency

Heat required to melt the joint Net heat supplied H, = Net heat available at the weld

Heat source

fi

MMA/GMA

SAW

GTAW

0.8 - 0.66 0.9 - 0.99 0.21 - 0.48

fx f2 EI vQ

A.. =

Example 1. An arc weld pass is made on steel under the following conditions :

E = 20 V I = 200 Av = 5 mm/s

f1 = 0.9 f2 = 0.3 Q = 10 J/mm3.

Estimate the cross-sectional area of the weld pass.

Solution.

A = (0.9)(0.3)(20)(200) = mm[4]. Ans.

w (5)(10)

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