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GTAW Pulse Frequency

GTAW Pulse Frequency

GTAW Pulse Frequency

I'm reviewing a WPS for auto GTAW used to make fillet seal welds in heat exchangers on 0.5" Ø nickel alloy tubes.
It uses the following parameters:
Root pass
Peak: 62A, 0.1s dwell
Low: 40A, 0.1s dwell
Travel speed 4.3 ipm
The subsequent passes have 1/3 higher peak current and with the same low current and dwell times, which amount to 5 cps.
My question is this:
At 5 cps, does pulsing actually provide an advantage compared with constant current of the same mean value? The frequency seems quite high compared to what I am more familiar with in heavier wall pipe welding applications.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: GTAW Pulse Frequency

Increased penetration from the higher peak amperage, better control over bead shape/profile/width (especially in sluggish materials).

RE: GTAW Pulse Frequency

I understand how it works, I'm just not convinced that 5 cps is slow enough to obtain the desired effect.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: GTAW Pulse Frequency

Higher PPS also tends to constrict/focus/stiffen the arc so it doesn't wander and can make a slightly narrower weld.

RE: GTAW Pulse Frequency

ASW Welding Handbook VOL-2 Recommendations:- The GTAW process generally ranges from 2 seconds per pulse to 10 pulses per second, with the lower frequencies most commonly recommended. This comes to 30 pulses/min to as high as 600 pulses /min. Typically lower pulses would work better for seal welding of 0.5" Ø nickel alloy tubes.Higher pulses under present context may just cause burn through, which is better recommended for thicker walled weld joints.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist

RE: GTAW Pulse Frequency

We weld thin stainless with 5-10kHz pulse, it all depends on the application.
Given the multiple effects of pulsing I see no reason to question this pulse rate.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: GTAW Pulse Frequency

OK, between these answers and some intensive research I've learned what I need to know.
Thanks to all.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

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