E347LT1-1 Shielding Gas: CO2 or Argon-CO2 Mixture?

When welding stainless steel with E347LT1-1 flux-cored wire, shielding gas has a direct influence on arc behavior, penetration, spatter, bead appearance, and overall welding performance. Two gas options are commonly discussed: 100% CO2 and an Argon-CO2 mixture.

So, which shielding gas should you use for E347LT1-1?

The short answer is that 100% CO2 is the standard shielding gas associated with the E347LT1-1 classification. An Argon-CO2 mixture may also be suitable when the welding wire carries the appropriate additional classification, such as E347LT1-4, or when it is approved by the applicable welding procedure.

Understanding the differences between these gases can help welders achieve better arc stability, weld quality, productivity, and cost control.

What Is E347LT1-1 Flux-Cored Wire?

E347LT1-1 is a stainless steel flux-cored welding wire designed for gas-shielded flux-cored arc welding, or FCAW-G.

It is primarily used for welding stabilized austenitic stainless steels such as Type 347 stainless steel and related grades. The deposited weld metal contains niobium, also traditionally called columbium, which helps stabilize carbon and improve resistance to intergranular corrosion in appropriate service conditions.

E347LT1-1 is commonly selected for applications involving:

• Stainless steel piping

• Pressure vessels

• Heat-resistant equipment

• Chemical processing equipment

• Petrochemical fabrication

• Power generation components

• Tanks and industrial vessels

• High-temperature stainless steel structures

Its flux-cored design can provide good productivity, convenient positional welding, slag coverage, and consistent weld bead formation when the welding parameters and shielding gas are properly controlled.

What Shielding Gas Is Used for E347LT1-1?

For the E347LT1-1 classification, 100% CO2 is the primary shielding gas.

This is an important point because the shielding gas is connected to the classification of gas-shielded stainless steel flux-cored electrodes.

In practical welding operations, however, some stainless steel flux-cored wires may carry dual classifications, for example:

E347LT1-1 / E347LT1-4

In this situation, the wire may be suitable for both:

• 100% CO2

• Argon-CO2 shielding gas mixture

A commonly used mixed gas is approximately 75% Argon and 25% CO2, although the exact composition should always follow the welding consumable specification and approved welding procedure.

Therefore, the question is not simply whether Argon-CO2 can physically produce a weld. The more important question is whether the particular wire and welding procedure are qualified for that shielding gas.

CO2 vs Argon-CO2 for E347LT1-1

Both gas systems can provide useful welding characteristics, but they do not produce identical arc behavior.

The best option depends on the consumable classification, welding position, joint design, material thickness, production requirements, and approved welding procedure.

Advantages of 100% CO2 for E347LT1-1

1. Lower Shielding Gas Cost

One of the main advantages of pure CO2 is cost.

For high-volume stainless steel fabrication, shielding gas consumption can represent a significant operating expense. Using 100% CO2 can reduce gas costs compared with Argon-rich mixtures.

This makes CO2 attractive for applications where welding productivity and operating cost are important.

2. Strong Penetration

CO2 generally produces an energetic welding arc that can provide strong penetration.

This can be beneficial when welding medium or heavier stainless steel sections where adequate fusion at the joint root and sidewalls is important.

However, deeper penetration does not automatically mean better weld quality. Voltage, wire feed speed, travel speed, torch angle, stick-out, and joint preparation must also be correctly controlled.

3. Widely Used for E347LT1-1 Classification

Because E347LT1-1 is associated with CO2 shielding, pure CO2 provides a straightforward choice when following the intended classification conditions.

This can simplify welding procedure development when the consumable specification already identifies CO2 as the required shielding gas.

4. Good Productivity

With properly selected welding parameters, E347LT1-1 with CO2 shielding can provide good deposition rates and reliable performance for stainless steel fabrication.

It is therefore suitable for many production environments where productivity is a major consideration.

Disadvantages of 100% CO2

Although CO2 is economical and effective, it also has some trade-offs.

More Spatter

Pure CO2 can produce more spatter than an Argon-rich shielding gas mixture.

Higher spatter levels may increase:

• Post-weld cleaning

• Grinding requirements

• Labor time

• Consumable waste

Proper parameter optimization can reduce spatter, but it may not completely eliminate the difference.

Rougher Arc Characteristics

The arc may feel more active or forceful compared with an Argon-CO2 mixture.

For experienced welders this is usually manageable, but mixed gas may provide a more comfortable operating characteristic in some applications.

Bead Appearance

CO2 can still produce attractive stainless steel welds, especially with a properly formulated flux-cored wire.

However, an Argon-CO2 mixture may provide a smoother arc and more uniform bead appearance in certain welding conditions.

Advantages of an Argon-CO2 Mixture

When the welding wire and procedure permit mixed gas, an Argon-CO2 blend can offer several advantages.

1. Smoother Arc

Adding Argon generally changes the arc characteristics and can produce a smoother, more stable welding experience.

This can make it easier for the welder to control the molten weld pool, particularly during positional welding.

2. Reduced Spatter

An Argon-rich mixture can often reduce spatter compared with pure CO2.

Less spatter means less time spent cleaning the finished weld and surrounding stainless steel surface.

For applications where appearance matters, this can improve overall productivity even though the shielding gas itself is more expensive.

3. Improved Bead Appearance

Argon-CO2 mixtures are often selected when weld appearance and bead consistency are important.

A smoother arc can help produce:

• More uniform bead profiles

• Cleaner weld toes

• Reduced surface spatter

• Better visual consistency

This can be particularly useful for stainless steel fabrication where finished appearance is part of the quality requirement.

4. Easier Weld Pool Control

A smoother arc can improve control during vertical and overhead welding.

However, welding performance depends heavily on the specific flux formulation, wire diameter, welding current, voltage, travel speed, and operator technique.

Disadvantages of Argon-CO2 Mixtures

Higher Cost

Argon is more expensive than CO2 in many markets.

For high-volume welding operations, this difference can become significant.

Therefore, a mixed gas should not automatically be considered more economical simply because it produces less spatter.

The total welding cost should consider:

• Shielding gas cost

• Welding speed

• Deposition efficiency

• Cleanup time

• Rework

• Labor cost

• Weld quality

Welding Parameters May Need Adjustment

Switching from CO2 to Argon-CO2 without changing welding parameters may produce undesirable results.

Arc voltage, wire feed speed, travel speed, and other variables may need to be optimized for the new gas.

A parameter set developed for 100% CO2 should not automatically be assumed to be ideal for an Argon-CO2 mixture.

Classification Must Be Verified

This is one of the most important considerations.

If the electrode is identified only as E347LT1-1, the user should not automatically substitute an Argon-CO2 mixture.

Check whether the consumable also carries the appropriate classification for mixed gas and whether the welding procedure permits the change.

Is 75% Argon and 25% CO2 Suitable for E347LT1-1?

A 75% Argon / 25% CO2 mixture is commonly associated with certain stainless steel flux-cored welding applications.

However, whether it is suitable depends on the exact classification of the wire.

If the consumable is dual-classified as something such as:

E347LT1-1 / E347LT1-4

then the manufacturer may qualify the wire for operation with both CO2 and an Argon-CO2 mixture.

If the wire is classified only as E347LT1-1, use the shielding gas specified for that classification unless an approved welding procedure establishes otherwise.

Does Shielding Gas Affect Weld Metal Properties?

Yes.

Shielding gas affects more than arc appearance.

Changing the gas composition can influence:

• Arc energy

• Metal transfer

• Penetration

• Weld pool behavior

• Oxidation

• Slag characteristics

• Bead geometry

• Chemical composition of deposited weld metal

• Mechanical properties

For this reason, shielding gas should be treated as an important welding procedure variable rather than simply a consumable preference.

When welding components governed by a qualified WPS, the specified shielding gas composition and flow conditions should be followed.

Recommended Gas Flow for E347LT1-1

The correct shielding gas flow depends on several factors, including:

• Wire diameter

• Welding current

• Nozzle diameter

• Joint geometry

• Welding position

• Draft conditions

• Torch-to-work distance

Using too little gas can cause inadequate protection of the weld pool.

Using excessive gas is also undesirable because high flow can create turbulence and draw surrounding air into the shielding zone.

The correct approach is to use the gas flow range specified by the welding consumable data and the qualified welding procedure.

Wind and drafts should also be controlled when performing FCAW-G.

Which Gas Produces Better Penetration?

For many FCAW applications, 100% CO2 provides a relatively energetic arc and strong penetration characteristics.

An Argon-CO2 mixture may provide smoother transfer and more controlled arc behavior.

However, penetration is not determined by shielding gas alone.

Important variables include:

• Welding current

• Voltage

• Wire feed speed

• Electrode extension

• Travel speed

• Torch angle

• Joint preparation

• Base material thickness

Gas selection should therefore be considered as part of the complete welding procedure.

E347LT1-1 Which Gas Produces Less Spatter?

An Argon-CO2 mixture generally produces less spatter than pure CO2 when the wire and parameters are designed for that gas.

This is one reason mixed gas is attractive for applications where weld appearance and reduced cleanup are priorities.

However, modern flux-cored wires can also provide good low-spatter performance with 100% CO2 when operated within the correct parameter range.

E347LT1-1 Which Shielding Gas Is More Economical?

If only the gas price is considered, 100% CO2 is usually the more economical option.

But gas price is only one part of welding cost.

Consider this example:

A mixed gas costs more but reduces spatter and cleanup time.

In that case, the additional gas cost may be offset by lower labor and finishing costs.

Conversely, in heavy industrial fabrication where appearance is less critical and welding volume is high, CO2 may provide the better overall economic result.

The best choice should be based on total welding cost per completed joint, not simply shielding gas price.

E347LT1-1 CO2 or Argon-CO2: Which Should You Choose?

Choose 100% CO2 when:

• The wire is classified specifically as E347LT1-1

• Lower shielding gas cost is important

• Strong penetration is required

• The welding procedure specifies CO2

• Higher production volume makes gas cost important

Consider an Argon-CO2 mixture when:

• The wire carries the appropriate mixed-gas classification

• The approved WPS permits mixed gas

• Reduced spatter is important

• Smoother arc behavior is preferred

• Weld appearance is a priority

• Positional weld pool control needs improvement

The consumable classification and qualified welding procedure should always take priority over general preferences.

Common Mistakes When Selecting E347LT1-1 Shielding Gas

Using Argon-CO2 Without Checking the Classification

Do not assume that every E347LT1-1 wire can be used interchangeably with mixed gas.

Always confirm the complete electrode classification.

E347LT1-1 Using Pure Argon

Pure Argon is generally not the normal shielding gas specified for this type of stainless steel flux-cored electrode.

The flux system and arc characteristics are typically designed around CO2-containing shielding gases.

E347LT1-1 Keeping the Same Parameters After Changing Gas

A change from CO2 to Argon-CO2 may require parameter adjustments.

Using identical voltage and wire feed settings may not provide optimum performance.

E347LT1-1 Increasing Gas Flow to Solve Every Porosity Problem

More gas is not always better.

Porosity may also result from:

• Contaminated base metal

• Moisture

• Excessive stick-out

• Poor nozzle condition

• Gas leaks

• Wind

• Incorrect torch angle

Troubleshoot the complete shielding system before simply increasing gas flow.

E347LT1-1 Final Thoughts

When choosing E347LT1-1 shielding gas, 100% CO2 remains the standard option for the E347LT1-1 classification. It offers good penetration, reliable welding performance, and relatively low shielding gas cost.

An Argon-CO2 mixture can provide advantages such as smoother arc characteristics, reduced spatter, easier weld pool control, and improved bead appearance. However, it should only be used when the welding consumable has the appropriate classification and the welding procedure allows it.

For production welding, the best choice is not simply the gas that creates the smoothest arc or has the lowest cylinder price. The correct shielding gas is the one that provides qualified weld quality, stable performance, acceptable productivity, and the lowest total welding cost for the application.