Q: I am looking at generating a full penetration weld to splice two aluminum plates, and I am considering using arc gouging. Can this be done?

A: Air arc gouging can be used on aluminum but it is not a typical process.

That is because the process will leave a rough-looking, porous, carbon-rich surface behind.

Before welding on such a surface, you will need to remove — that is, grind — about ⅛ in. off the gouged surface.

Typically, this situation can be avoided by proper welding joint design and, when necessary, it makes more sense to use a router or die grinder with a carbide cutter that has an appropriate profile for the depth of the cut.

Q: We currently have a crew ready to install a furnace in a foreign country. As part of the installation, they must weld two flanges together. The flanges are made of Rolled Alloys 330 stainless steel. We requested that the customer provide the 330 filler metal required for the job. Unfortunately, they are only able to provide us with a 316L filler metal. Is there a problem welding this flange with the 316?

A: First, the use of 316L filler would be incorrect.

It most likely would hot crack and would not have the resistance to oxidation or to carburization that the Rolled Alloys 330 have at the temperatures that are to be generated by the furnace.

The question of using an alternate filler metal is strongly dependent on the environment the weldment will see in service.

If the furnace is going to be run at high temperatures — approaching 2000 deg. F — and/or creating a strongly carburizing environment, you want to use a filler metal with a composition matching the Rolled Alloys and referred to as RA330-04.

The RA330-04 is designed to have a manganese level of around 5 percent, which will increase the resistance to centerline cracking that is prevalent with fully austenitic alloys such as the Rolled Alloys 330.

Do not use the plain ER330 filler metal without the elevated manganese. That that will centerline crack. Rolled Alloys has a good welding document on their website at the following link: www.rolledalloys.com/trc/viewdoc.aspx?n1=heatresist&n2=WELDING.

For lower temperature operation or acceptance of lower oxidation résistance, you may consider ERNiCro-3 or ERNiCrFe-2 which may be more readily available but at an increased cost.

Welding process also can affect the propensity to centerline crack.

Better resistance to cracking will come from electrodes that have a lime “-15” coating, such as RA330-04-15.

GMAW wires are available but bead shape should be more convex to prevent cracking. GTAW is also a possibility, but avoid doing any autogenous — no filler — welding, as it will centerline crack so add a filler metal such as the Rolled Alloys 330-04.

Q: I am welding austenitic stainless steel with the GTAW or TIG welding process, and would like to use a tungsten such as the 2 percent thoriated tungsten that does not produce a radioactive dust when grinding the point. What are my options?

A: Your question is very good and often overlooked when selecting GTAW electrodes.

Tungstens that are either ceriated or lanthanated are non-radioactive and should produce excellent results on DC welding current welding stainless steel without the potential hazard when grinding the point onto the electrode.

You also should consider the type of grinding equipment you are using to produce the point on the electrode, and choose equipment that will safely remove and contain the dust produced by the operation.

Be sure to read, understand and obey all safety related materials provided by the manufacturer of the tungsten material selected and grinding equipment.

Send us your questions.

For answers to more of your questions, visit our online discussion forums at www.weldingdesign.com

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This column is sponsored by Penton and the Lincoln Electric Co., Cleveland. Dave Barton is a senior welding engineer in the Application Engineering Group of The Lincoln Electric Co. He oversees welding procedure development for both new technology and existing products, performs failure analyses for customers, and serves as a consultant on welding application problems. Barton has been with Lincoln Electric for 21 years. Send your questions for Mr. Barton in care of WDF by e-mail to: askdav@penton.com.