Penetration of welds

Date 10-13-2004 19:05

It would be incorrect to say that one particular process has more penetration than another. As with most things in welding, it depends on the specific application. If you have a particular application in mind, give the details, and then I'm sure many folks here could weigh in.

John

By RonG

Date 10-13-2004 19:16

None of the above and All of the above. Is this one of those "I wanna burn it in real deep things"?

There is more to pentration than just process: Volts, Amps & Speed to mention a few.

If you mean "Short Arc" when you use GMAW, you can cross it off your list.

With GTAW (manual) you can hold back the filler and ply more heat in to the work, but for what purpose?

The real question is "How much penitration do you need (want)? Penitration can be equated to "dilution" in some applications and of that the less the better.

By jefflll (*)

Date 10-14-2004 01:12

my instructor at school asked everyone this ? and i wanted to know the response from others. what has the most penetration when running a normal bead. im not saying crank the heat way up. a normal and correct bead

By thirdeye (***)

Date 10-14-2004 03:33

One point goes to your Instructor for asking a question that will make you take a good look at all of the variables specific to each process that you are asking about. And one point will go to you if approach the answer to this question with some sound examples of how different variables can affect penetration. I'm betting that your classroom discussion will be a good one. Let us know how it turns out.

By Lawrence (*****)

Date 10-14-2004 18:47

Hey Jeff,

I'm betting your instructor really wanted you to hit the textbook and do a bit of research. This is a good idea because good welders do more than just pull the trigger or lay down a bead, they have an understanding of process control and arc behavior.

So what I'll do is share a few comparisons with you but not tell you why these things are true. This way you have some hints, but can't give a complete answer without doing some research yourself.

Gas shielded FCAW electrodes such as E71T1 (as observed in macro etches) will penetrate deeper than GMAW in either short circut or spray transfer modes. This is true for all wire diameters.

However, Shield gas can have significant effect on penetration with GMAW in both short circuit and spray transfer modes. For instance; in short circuit mig straight C02 has a much different penetration profile than a 75% argon 25% CO2 gas mixture, but you will have to look up which penetrates deeper and why.

GTAW will have different penetration profiles with different polarities, DC-, DC+, and AC all produce radically different penetration profiles, furthermore, with AC GTAW balence control settings have a great impact on penetration when welding Aluminum. Lastly, commercial fluxes added to the base metal or in tubular filler rods can increase GTAW penetration more than 2X what it would be normally.

SMAW, again, each electrode type has its own flux coating which determines polarity and penetration. Some SMAW electrodes penetrate more at a given amperage than GMAW and GTAW, some penetrate less.

It's a very complicated question that I bet was intended to get you to ask more questions yourself. I hope this helps you frame some good ones.

By jefflll (*)

Date 10-14-2004 23:11

thats some indepth stuff. i really just need to know what is best all around without complicating the new students,some dont know what FCAW,SMAW, etc means. thanks for all the help.

By OSUtigger (**)

Date 10-15-2004 00:29

jefflll,

Basically what Lawrence is saying is there is no short, un-complicated answer and answering will require quite a bit of learing. I would compare the question you are asking to asking which mode of transportation is faster, a boat or an automobile? Once you ask this question, you need to know if the travel route is water or land. Even then, if all you are wanting is sheer speed, you need to define how much power are given to each, in other words, the rules behind the question. This is a case of why the question was asked is more important than what question was asked. If you really want to be able to answer your instuctor's question, you have to learn the subject matter. Lawrence gave you a great starting point, and there is plenty of information regarding what you are looking for right here on the web.

Good luck!
G. L.

By chinnlab Date 11-16-2004 19:54

In GMAW, which has the spiked penetration profile, and which has the deep oval nugget profile--100% CO2 or 100% Argon?

By Lawrence (*****)

Date 11-16-2004 22:23

Chinn

For mild steel, 100% Argon is not traditionally used. The Spiked profile you mention can be obtained when O2 is added to Argon-C02 mixtures to create a tri-mix

Here is everything you ever wanted to know about GMAW shielding gasses and most likely, a few things you never considered
http://weldreality.com/MIG_welding_gases.htm

By brande

Date 11-20-2004 06:18

You all are reading more into this than what is there.

Weld penetration is directly related to arc density-period.

The smaller the electrode at any given amperage, the higher the arc density.

Yes, gas shielding can have a small effect on this, but really not enough to be concerned with.

The Seawolfe submarine is welded with hard (bare)wire-you take it from there.

Good Luck

brande

By JINX

Date 11-23-2004 21:26

The answerer to your question could be found in an AWS publication.
Ask you instructor if he has or can obtain a copy of the AWS Welding Handbook Volume 2, either the eighth or ninth edition titled "Welding Processes." There is a chapter in this publication for each process you are interested in knowing the weld fusion/penetration profile. Each chapter will explain the importance of using the correct power source setting, and how to use each process to its full potential. Hope this helps.