Welding process clarification

By Lawrence (*****)

Date 05-17-2007 11:42

Kevin,

Welcome to the forum!

I asked the same question recently and was directed to view MCAW as synonomous with GMAW for D1.1 "process" purposes, even though the wire was tubular.

By js55

Date 05-17-2007 13:39

Nobody really knows what to do with the metal cores. The industry is sort of in definitional transition right now, IMO. Its not a flux core. There are no fast freezers, no deoxidizers or denitridizers, no shileding gas formers, no alloying elements or mechanical property improvers. Just metal powder. But its not a solid either, obviously. It is as Lawrence said, tubular.
And I'm not sure the A5 committee is ready to start a whole new family of specifications right now.
However, I do believe that metal core is not going away. The confusion will continue (I actually had some sales reps for a prestigious and reputable filler metal company claim that they had an all position metal core-so if filler reps don't understand the fundementals of metal core who else out there don't) and the C designation will eventually drive A5 to bite the bullit and spec em seperately. Maybe not.

By Kevin McConnell Date 05-17-2007 15:16

Many thanks, I had suspected this would be the case but need a bit of confirmation.

By 803056

Date 05-17-2007 21:09

I believe the metal cored filler metals for carbon steels are contained in AWS A5.18 and A5.28 with the solid filler metals used for GMAW.

The metal cored wires are not the same as those used for FCAW. In general they are treated in the same manner as the solid electrodes used for GMAW for welder qualification and procedure qualification by AWS and ASME.

If the welder is qualified for solid wire, he/she is qualified for metal cored wire if the mode of transfer is not affected.

Best regards - Al

By Patrick Snyder Date 05-24-2007 19:08

Lawrence,
I am new to the forum and I am suprised that I was able to see that there are others that are also confused about the MCAW classification. I read all the posts and I guess that since all the welders in my shop are qualified to D1.1 for GMAW 2G that it will also cover MCAW, correct?

By Kix

Date 05-25-2007 11:57

Keep an eye on your tensile strengths with the MCAW and GMAW wire. If the MCAW wire is a higher tensile or a different dia then you will have to requalify and qualify a new procedure. Table 4.5 P.138 D1.1 2006

By welder5354 (**)

Date 05-27-2007 05:37

Using MCAW requires 90%(arg)/10%(co2) gas for best results. So, therefore the welder must do a separate test for the MCAW process.
ASME Sec. IX
QW-408.2
A separate procedure qualification is required for each of the following conditions:
(a) a change from a single shielding gas to any other single shielding gas
(b) a change from a single shielding gas to a mixture of shielding gasses, and vice versa
(c) a change in the specified percentage composition of a shielding gas mixture
(d) the addition or omission of shielding gas
The AWS classification of SFA-5.32 may be used to specify the shielding gas composition.

By Lawrence (*****)

Date 05-27-2007 12:05

5354

Not sure where you get the 90/10 *requirement*

A quick check reveals that Trimark, Hobart and Corex, all provide a range from 75%-90% argon/C02 for their MCAW wire.

In fact, in this Corex data sheet the mechanicals provided as an example were run with 75/25
http://www.hobartbrothers.com/pdf/datasheets/MetalCor6.pdf

Same for TriMark
http://www.hobartbrothers.com/pdf/datasheets/Metalloy70X.pdf

By Patrick Snyder Date 05-29-2007 16:54

If I have guys qualified to 1/16 FCAW 2G does it qualfy them for diameters less than 1/16 or do I need to requalify for each change in diamter no matter if it's larger or smaller diameter? Also, would I have to do the same for using metal cored wires? If I qualify my guys on 1/16" metal cored 2G would that also qualify them for 0.045 GMAW 2G, or do I need to have a separate test for each wire?

By ssbn727 (*****)

Date 05-30-2007 00:50

What code or standard are you referring to?

Respectfully,
Henry

By Patrick Snyder Date 05-30-2007 12:12

I am sorry, D1.1.

By Kix

Date 05-30-2007 13:12

For your first question about the flux core for D1.1 you will not have to reqaulify a new WPS or retest your welders if you downsize in your wire dia. If you increase you wire dia you will have to reqaulify. Same goes for your tensile strength, if you increase your tensile you will have to requalify, but if you decrease you tensile your in the clear. For your second question the answer is here as well on Page 138 table 4.5 #10 for GMAW( Witch MCAW falls under) states a change in nominal filler dia by any increase or decrease will subject you to an essential variable that will throw you out of your current WPS. So you will have to qualify a new WPS and test your welders to that. Your tensile strength on the wire is also an essential variable so keep an eye on that.