Your Guide to Shielding Gases

Revised 2020 edition Your guide to shielding gases 2

Introduction What are Shielding Gases?

Molten metal is highly reactive to contamination through contact with excessive amounts of atmospheric gases. This can cause serious weld defects, hence the need for a gas to ‘shield’ the weld pool from the atmosphere. Almost all welds produced today use some form of shielding gas.

However, the right choice of shielding gas can also give you so much more: improving deposition rates, fusion, penetration, corrosion resistance and cosmetic profile – in other words all the key elements of a successful weld.

Read on to discover the difference shielding gases could make to your business. Your guide to shielding gases 3

Your Guide to Shielding Gases

The Purpose of this Guide Key takeaways → To explain why certain gas mixes are suited to particular jobs →  is still an effective versatile → To demonstrate the performance benefits of advanced shielding gases gas but other mixes will give you → To understand the business case for better results for many jobs trying them. → Precision-mixes in shielding

Who’s it for? gases have now optimised weld

This guide is for all welding companies but performances particularly those who regularly: → Improvements come in every

→ Use pure argon to TIG weld all kinds area: weld quality, speed and of metals → Use pure argon to MIG weld aluminium reduced pre and post weld → Use an argon/CO₂ or argon/O₂ mix to treatments MAG weld . → Increases in productivity and efficiencies overshadow any per unit increase in gas price Beyond Argon Looking enough any more?‘enough ‘jobbing all-rounder‘ good Is the performance of a

benefits. optimum and youneed results the precisely you to give mix gases aspecific choose can you So materials. and welds certain for suited best it that make characteristics gas has distinct Each marginal. longer are no selection gas shielding of correct benefits the that demonstrates data hard but improvement, aslight just for gas shielding your to wouldn’t change It make sense enough any more? good all-rounder’ of a‘jobbing performance the is while customers demand ever-higher standards, tighter getting margins with But results. bring does it and it, with comfortable feel probably they argon, use just your If gas. jobbing all-round agood it made has versatility its many, For decades. for welding TIG when gases of shielding workhorse willing the been has Argon while. Yes,while. it’s bullet. a silver your worth to be difference enough abig produce can else, it nothing and makeyou change, that steel.) If stainless argon/O₂ welding MAG for mix argon/CO₂ astandard use or traditionally you if considering worth also is (This instead. gas shielding appropriate the use and to find time the taking is profitability and productivity your key the Now to boosting everything. for not but welding TIG when argon aplace for still is There well. as better often is quality weld the and welders, skilled extra employ than gas different to buy it’s effective cost alot more throughput, welding your to want you increase their can productivity increase dramatically. If gas shielding adedicated use they when and workforce, skilled your is cost highest your far by line? Because bottom your help this does How Your guide to shielding gases 4

95%). to (90% mixtures Gas of

shielding gases and the main component component main the and gases shielding

Mainly used as addition to Duplex Duplex to addition as used Mainly →

aluminium). weld to used gases in O₂ of applications

ppm 500 (e.g. mixtures gas to elements shielding root for suitable be Can →

Gains benefits from adding trace trace adding from benefits Gains → shielding for own its on used Rarely →

Nitrogen Relatively new Relatively →

Doped gases Doped

a priority, such as office furniture, etc. furniture, office as such priority, a

carbon/ferritic steels. carbon/ferritic is appearance where steel carbon thin

Not suitable for welding aluminium or or aluminium welding for suitable Not → on welds for ideal is mix (2%) Ar/O₂ →

and surface oxide formation oxide surface and tension surface Reduces →

deposition rates and reduced distortion distortion reduced and rates deposition arc the stabilise to argon to Added →

penetration depth ratio’, higher higher ratio’, depth penetration gas shielding

Produces better ‘bead width to to width ‘bead better Produces → a as own its on used be Can’t →

Oxygen much more concentrated ‘hot spot’ ‘hot concentrated more much

Constricts or narrows the arc giving a a giving arc the narrows or Constricts →

High thermal High →

shielding gas shielding steel. primed or rusty dirty,

a as own its on used be Can’t → welding when help CO₂ of levels Higher →

Hydrogen characteristics and benefits. and characteristics Ar/O₂ than steel stainless

for welds better produces mix Ar/CO₂ →

to shield the weld pool. Each has its own own its has Each pool. weld the shield to and create arc instability arc create and

mixes. Ar/CO₂ spatter increase can 20% over Additions →

used either on their own or in a mixture mixture a in or own their on either used

or argon to added when etc) formation, profile penetration improves

rates, surface profile, reduced gas pore pore gas reduced profile, surface rates, and transfer heat increases addition CO₂ →

There are a number of gases that can be be can that gases of number a are There

Carbon Dioxide Carbon deposition (penetration, weld deposited

Will improve virtually all aspects of the the of aspects all virtually improve Will →

the penetration profile penetration the

What’s What? What’s

Broadens the weld pool and improves improves and pool weld the Broadens → mixtures. gas

High thermal conductivity thermal High → all almost for base or own its on Used →

due to problems with HF arc initiation arc HF with problems to due ignition arc Easy →

Shielding Gases. Gases. Shielding

Rarely used on its own for TIG welding welding TIG for own its on used Rarely → Inert →

Argon

5 Your guide to shielding gases shielding to guide Your Your guide to shielding gases 6

The Right Gas Mix For Your Job

BOC offers a wide range of advanced shielding gas mixes tailored to provide optimum performance for specific jobs. Here are some of our most popular.

MAG welding on thin section MIG and TIG welding of thinner TIG welding of thin section stainless steel section aluminium and copper austenitic stainless steel STAINSHIELD® Light ALUSHIELD® Light (up to 3 mm) (argon +85% helium +1.5% CO₂) (argon +30% helium) STAINSHIELD TIG (argon +1.5% )

MAG welding on heavy section MIG and TIG welding across a range stainless steel of thickness in aluminium and TIG welding of heavier section STAINSHIELD Heavy copper. TIG welding of carbon and austenitic stainless steel (above (argon +55% helium +2% CO₂) ferritic/martensitic stainless steel 3 mm) and automatic applications ALUSHIELD Universal SPECSHIELD® 5% hydrogen (argon +50% helium) (argon +5% hydrogen) MAG welding across a range of thickness in stainless steel STAINSHIELD Universal MIG and TIG welding of heavy (argon +38% helium +2% CO₂) section (above 6mm) aluminium BOC also stock many other Excellent for pulsed welding. and copper ALUSHIELD Heavy variants of shielding gas to (argon +75% helium) provide the bespoke solution for your welding task. Welding for profitYour // Rebuildingguide to shielding the skill gases base 077

Advanced Shielding Gases. The Benefits

Advanced Improved Improved Reduced Materials + Efficiency + Weld Quality = Cost

As we’ve highlighted in this These benefits can be metallurgical such as improved when MAG welding . A cleaner finish resistance to corrosion, mechanical such as improved is particularly important when the cosmetic guide already, most welders use penetration and reduced porosity and financial due to appearance of the weld is a priority. Remember, improved productivity and reduced weld cost. spatter is wasted welding wire so reducing or a shielding gas merely to protect eliminating it also helps reduce consumable costs. Rising Productivity their weld from the damaging • Faster welding – using the correct mix of gas can Improved weld quality effects of excess and give you better deposition rates. Adding the right The correct choice and use of shielding gas will amount of hydrogen to argon for TIG welding influence virtually all aspects of the weld such from the atmosphere. austenitic stainless steel produces a more fluid as penetration profile, weld bead shape and size, weld pool and improved welding speeds. Equally, corrosion resistance, pore formation and overall weld But with the right mix of shielding adding helium to argon achieves faster welding integrity. and also may reduce or eliminate the need to • Increased heat and fluidity of the weld pool – the gases other important benefits preheat components before welding can begin. most fundamental benefit. Good quality welding • Less time spent tidying-up spatter – removing starts with a good quality weld pool and using can be achieved. spatter after welding is costly and can leave the right shielding gas can improve the transfer surface imperfections which can have an adverse of energy from the arc to the weld. Higher quality effect on surface coatings, painting etc. Prevention welds will reduce defects and re-works. is the best cure and using the right shielding gases can make a real difference to spatter generation from the weld pool, for example Your guide to shielding gases 8

The Cost-benefit Calculation

We regularly visit welding companies to run trials. This helps us to identify the best shielding mix and to demonstrate the benefits it can bring in raised productivity and efficiencies. See the following results from real trials.

Company A Company B Company C Company D

45% increase in welding Overall, a reduction in production costs A 76% reduction in welding time and a 22% increase in welding speed 30% reduction in purging of over 50%. 73% reduction in total production cost.

Using argon shielding gas on straight line Orbitally TIG welding austenitic steel , Depositing TIG welds on 240mm long lap TIG welding stainless steel components. welders, manufacturing duplex domestic using argon as both shielding and back joints in 3.00mm thick 4043 aluminium, heating boilers. purging gas. using argon as shielding gas. Trial A replacement argon/hydrogen mix. Trial Trial Trial A replacement argon/nitrogen mix. A replacement argon/hydrogen mix. A replacement argon/helium mix. Trial result A 76% reduction in welding time and Trial result Trial result Trial result a 73% reduction in total production Improved product quality and around Greatly improved weld quality, with Welding speed faster with improved, cost. Any per unit increase in gas price 22% increase in welding speed with need for post weld cleaning almost flatter weld profile and greatly was completely over-shadowed by the a reduction in post weld cleaning eliminated, a 45% increase in welding reduced surface oxide formation. significant reduction in gas used for each operations. speed plus a 30% reduction in purging Overall, a reduction in production component weld. gas consumption. costs of over 50%.

*Company names have been kept anonymous for data protection the norm. the processes have grown to be welding shielded gas then the 1940’s and 50’s. Since welding dates to back to optimise gases mixed or years. The use of individual industrial gases for over 140 producing been has BOC Gas Shielding Your Optimum Choose Help How BOC Can

forms on the surface of aluminium. surface the on forms layer oxide that the removing on spent time eliminate can mix to argon/helium an argon from switching example, For gas. shielding different a by completely choosing avoided or reduced be can both Often time. worker skilled of valuable agreat deal consume can which weld cleaning post and pre weld preparation includes That operational processes. also welding equipment, settings and all other you) for but solution best the find they until ones (and different mixes gas on trial will only not individual welding companies. They will advise at trials shop-floor running country the tour who engineers team of our is technical toCentral this business benefits to our customers. improve and productivity weld quality and deliver to sector welding the with knowledge this sharing to We materials. are and committed tasks welding different for performance optimum to provide mixes gas We develop to research and continue benefits to your bottom line. to bottom your benefits gas alone can immediate bring and significant of shielding use your we refining have seen, As and consistent in quality your processes. site on to high or ensure lab the in of gas analysis professional undertake We also it. can repair or maintain required, if and, safely it’s working to ensure system gas-supply your check regularly sites. We’ll also at customer courses training safety We bespoke deliver gases. shielding of your use safe the on you guide We also can might help you? longer to ignore how it sense, can you afford any businessplain common Call it asilver bullet just or Your guide to shielding gases 9 Free On-site Shielding Gases Review

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