7 Effects of Shielding Gas - The Fabricator
7 Effects of Shielding Gas - The Fabricator
7 Effects of Shielding Gas - The Fabricator
oaparams=2__bannerid=38__zoneid=1__cb=a760e405cd__oadest=http%3A%2F%2Fwww.us.trumpf.com%2F)
Home (/) / Article (/?filter=article) / Arc Welding (/?filter=article&category=arcwelding) / 7 effects of shielding gas
s+blend+can+help+or+hurt+you.++Find+out+what+effects+shielding+gas+has+on+your+weld+and+what+you+can+do+to+get+the+best+results.&img=http://image.thefabricator.com/a/7-
Depending on your application, various components of your shielding gas blend can help or hurt you. Find out what effects shielding
gas has on your weld and what you can do to get the best results.
Although you probably know that shielding gas is essential in most welding procedure specifications, you
may pay little attention when you're selecting it. A simple gas composition change can offer potential savings
in seven key areas, particularly in gas metal arc welding (GMAW).
Shielding gas typically isn't considered to have much of an effect on the cost of a welding operation. Many
welders don't fully understand the financial impact that shielding gas can have on the bottom-line cost of the
welding operation.
Which shielding gas composition you choose for GMAW can affect your welding operation in seven key
ways.
ADVERTISEMENT
(http://ads.thefabricator.com/delivery/ck.php?oaparams=2__bannerid=807__zoneid=19__cb=53e23c6c39__oadest=http%3A%2F%2Fbit.ly%2F2hPVzcH)
Single-wire GMAW can exceed deposition rates of 15 pounds per hour at 100 percent duty cycle. Argon content should be 85 percent or more to accomplish spray transfer. In
some cases, instead of using a conventional argon/carbon dioxide or argon/oxygen blend, using a helium-enhanced argon blend may increase weld metal deposition rates up
to 15 percent.
Although helium costs more than argon, shielding gas typically comprises less than 5 percent of the total welding cost, making the addition of helium something to consider
when choosing a shielding gas blend.
Electrode deposition efficiency is linked directly to the welding spatter level. High-argon blends typically produce the best results in spray transfer. Improved deposition
efficiency also can be a function of choosing the right welding parameters. A nonoptimized system—in which any number of parameters, such as gas flow rate and voltage,
aren't optimized—generally produces lower deposition efficiency and may contribute to increased postweld cleanup costs.
If you use spray arc transfer, generally the argon level should be 85 percent or more. Pulsed spray transfer with a 95 percent argon blend typically will yield the lowest spatter
levels when welding plain carbon steel. A three-part blend of argon, helium, and carbon dioxide can reduce weld spatter when joining galvanized steel or steel with some
residual surface oil or scale.
In general, GMAW is a slag-free process, but slag islands still are common on the bead surface. Powder and paint won't adhere to these silicon deposits. Low shielding gas
reactivity can help to reduce these surface residuals. If you're concerned about slag island buildup along the edge of the weld bead, work only with properly cleaned base
material and use a blend containing at least 90 percent argon with no oxygen. Choosing filler metal carefully also will help limit island formations.
Postweld cleanup can increase cost, reduce your arc-on time, and decrease the welding operation's duty cycle. Because it reduces spatter, an optimal argon blend may help
you reduce postweld grinding, which means you can dedicate more time to welding.
Color match typically is a concern when welding stainless steels. For the best color match, select a blend of argon or helium with low levels of oxygen or CO2 to minimize weld
surface oxidation. Oxygen-free blends produce less weld metal discoloration. To further minimize discoloration, use a low operating current and a large gas nozzle with close
nozzle-to-work distance to ensure good shielding gas coverage. When joining 300 series stainless steel, you can add a controlled amount of hydrogen—less than 5 percent—
to lessen oxidation and therefore improve bead color and enhance productivity. If corrosion resistance is important, limit CO2 content to less than 5 percent.
Filler metal diameter also plays a critical role in optimizing bead shape. A large wire size can make it difficult to control the weld bead size. An oversized weld bead can
increase welding costs by at least 50 percent. Choose your filler metal type and size based on the needs of your application.
Pure CO2 can help you achieve good weld penetration. The operating current, filler metal, and gas composition also affect the penetration profile. If you want deep
penetration, use an argon blend with a high percentage of CO2—15 percent to 20 percent—or perhaps consider adding helium to broaden and deepen penetration. This also
will contribute to better welding productivity.
5. Out-of-position Weldability
Shielding gases with greater reactivity, which use more CO2 or O2, will increase weld pool fluidity. For out-of-position work, this may force you to use slower wire feed rates,
which will decrease productivity.
The type of metal transfer you choose also is critical when trying to improve out-of-position control. High-argon blends with low reactivity generally perform well.
High-argon blends are less reactive than pure CO2 and generally produce less welding fumes under similar operating conditions. But lower fume generation doesn't always
equal lower exposure, so be sure to conduct measurements to ensure compliance with applicable permissible exposure limits.
The shielding gas you choose can affect many welding characteristics. Once you understand which properties are most important for your application, you can select the best
blend for the job.
www.praxair.com/metalfab (http://www.praxair.com/metalfab)
Contact via email (mailto:garth_stapon@praxair.com)
Kevin Lyttle
Development Scientist
Praxair Technology Center
175 E. Park Drive
Tonawanda, NY 14150
Phone: 716-879-7290
www.praxair.com (http://www.praxair.com)
Published In...
Related Companies
Praxair Inc. (http://directory.thefabricator.com/directory/showroom/praxair-inc)
Sort by Best
Recommend ⤤ Share
LOG IN WITH
Name
Still Building America—Austin Fahey does what he loves, sky-high ‘A livable wage’ and manufacturing
1 comment • 15 days ago• 3 comments • a month ago•
AvatarShinning_Light — Pretty good article. i'm learning to TIG and wonder if I ever AvatarJohn Storace — Out of biz and rightly so, where do you live in CA for $8-9?
will "get it". So thanks for the motivation, no excuses! Under an overpass?
Weld-Ed announces 2017 professional development workshops Who is the face of manufacturing?
3 comments • 3 months ago• 2 comments • 2 months ago•
AvatarSteve Corcoran — Thanks Vicki! AvatarDan Davis — We used a stock image for the column, Mr. Garcia. We don't know
his name. Let's just call him "Joe Welder."Thanks for the kind words!
(http://ads.thefabricator.com/delivery/ck.php?
oaparams=2__bannerid=806__zoneid=363__cb=5d59620d0e__oadest=http%3A%2F%2Fwww.fronius.com%2Fcps%2Frde%2Fxbcr%2FSID-403588D9-
9D176E68%2Ffronius_usa%2FAccuPocket-2017.pdf)
(http://ads.thefabricator.com/delivery/ck.php?
oaparams=2__bannerid=803__zoneid=20__cb=870b602920__oadest=http%3A%2F%2Fwww.diamondground.com%2F)
(http://ads.thefabricator.com/delivery/ck.php?
oaparams=2__bannerid=850__zoneid=21__cb=faecda3bec__oadest=http%3A%2F%2Finfo.binzel-abicor.com%2Fthe-complete-guide-to-fume-
extraction%3Futm_campaign%3DXtract%26utm_content%3DBanner%2520Ad%26utm_medium%3DPublisher%26utm_source%3DFMA)
FABTECH (/event/fabtech)
NOVEMBER 6-9, 2017 | CHICAGO, IL
(http://ads.thefabricator.com/delivery/ck.php?
oaparams=2__bannerid=915__zoneid=23__cb=16ae743538__oadest=https%3A%2F%2Fwww.schweissen-schneiden.com%2F)