7 Methods for Solving Burn-Through and Deformation During Stainless Steel Plate Welding

2. Insufficient Welding Speed

Slower speeds cause more heat accumulation per unit length. Studies show welding below 10mm/s on 3mm stainless steel concentrates heat, risking overheating and burn-through. Failing to adjust speed alongside power further increases this risk.

3. Laser Power – Thickness Mismatch

Each sheet thickness requires a specific power range. For 3mm stainless steel, 800–1200W is optimal. Using excessive power (e.g., 1800W) without increasing speed over-concentrates energy, causing burn-through. Inadequate power results in insufficient penetration.

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1. Uneven Thermal Expansion/Contraction

When welding 3mm stainless steel with a fiber laser, the heat source locally heats the metal. The welded area expands rapidly due to high temperatures, while the surrounding cold metal restricts this expansion. Thermal-mechanical analysis shows the temperature difference between the welded area and its surroundings can reach several hundred °C. This large temperature gradient generates internal stresses, which cause metal deformation as the material cools.

2. Heat Input & Thermal Conductivity Impact

For 3mm stainless steel, balancing heat input and thermal conductivity is critical. Stainless steel has lower thermal conductivity than some metals, so high heat input from a fiber laser—if not dissipated quickly—causes uneven temperature distribution in the sheet. Studies indicate excessive heat input can widen the heat-affected zone (HAZ) of 3mm stainless steel by 30–50%, intensifying internal stress and deformation risk.

✅ 1. Optimize Welding Heat Input & Parameters

Controlling heat input is critical for 3mm stainless steel welding with a fiber laser. Recommended parameters include:

• Laser Power: 800–1200W for 3mm sheets to prevent excessive heat accumulation.
• Welding Speed: 10–15 mm/s to ensure uniform melting without prolonged heating.
• Pulse Frequency: 50–80 Hz to balance energy distribution.

A DXTECH case study showed that reducing power from 1800W to 1000W and increasing speed from 8 mm/s to 12 mm/s reduced burn-through in 3mm stainless steel components by 70%.

✅ 2. Use Larger Nozzle Diameter for Enhanced Protection

Nozzle selection is a critical factor for weld quality. While smaller nozzles are typical for thin sheets, upgrading to a larger diameter (e.g., 12–15 mm) improves welding performance for 3mm stainless steel:
• Larger nozzles significantly expand shielding gas coverage, forming a stronger anti-oxidation barrier to prevent oxidation.
• They promote more uniform heat distribution in the weld zone, reducing the risk of local overheating and minimizing burn-through or excessive deformation.

✅ 3. Optimize Tungsten Electrode and Extension Length

When using a fiber laser welding machine for 3 mm stainless steel precision welding, tungsten electrode selection and adjustment are critical to achieving high-quality welds while minimizing burn-through and deformation.

• Use a φ1.5 cerium tungsten electrode and sharpen it to a sharp tip for concentrated heat input. A sharp electrode increases energy density at the weld point, enabling more efficient metal melting.
• Extend the electrode 5–8 mm beyond the nozzle to concentrate energy at the weld point. This method reduces the heat-affected zone (HAZ) by up to 28% in 3 mm stainless steel welding. Minimizing the HAZ significantly reduces heat-induced deformation risk. Additionally, focused energy melts stainless steel faster, improving welding efficiency, enhancing process control, and producing high-quality welds with minimal deformation.

✅ 4. Implement Strategic Welding Sequencing

The correct welding sequence is also critical for balancing thermal stress.

Symmetrical Welding

For structures with symmetrical welds, the recommended practice is to weld alternately on both sides. Evenly distributing heat input on both sides of the structure balances thermal expansion and contraction.

Asymmetric Welding

For asymmetric structures, start welding from the side with less welding volume. This method helps distribute stress evenly across the component. Starting from the side with less volume allows the material to gradually adapt to welding-induced thermal stresses, reducing the likelihood of excessive deformation in the final product.

✅ 5. Ensure Precise Assembly and Gap Control

Strict assembly tolerances are crucial for welding 3 mm thick plates.

Maintain Narrow Joint Gaps

Keep joint gaps ≤0.3 mm to prevent burn-through and excessive weld beads. In GTAW of 3-mm stainless steel, gaps over 0.3 mm disrupt arc distribution, increasing burn-through risks. Controlling gaps ensures precise heat input for high-quality welds with optimal penetration and smooth surfaces.

Use Precision Fixtures

Precision fixtures align components during welding, minimizing misalignment-induced stress. Widely used in aerospace and automotive sectors, they secure parts with high accuracy—vital for consistent, durable welds in structures like vehicle chassis or aircraft components.

✅ 6. Employ High-Precision Fixtures for Uniform Clamping

Rigid fixtures play a dual critical role in welding operations:

Clamping Force Balance

Fixtures suppress uncontrolled thermal expansion by evenly distributing clamping pressure.

Heat Dissipation

Metal fixtures—especially aluminum ones—act as effective heat sinks to regulate temperature gradients. CNC-machined aluminum fixtures (e.g., 6061-T6) exhibit excellent thermal conductivity, reducing localized overheating during stainless steel welding. In a case study of 304 stainless steel brackets (3 mm thick), these fixtures reduced angular deformation from 1.78° to 0.49°, confirming their effectiveness in mitigating deformation.

✅ 7. Leverage Fiber Laser Welding for Minimal Deformation

Fiber laser welding machines offer inherent advantages for 3mm stainless steel:

• Laser spot adjustment
  Adjustable laser spot size (20–50 microns) enables precise melting.
• Low Heat Input
  Non-contact welding minimizes thermal stress by reducing heat input. Fiber laser welding of 304 stainless steel produces a heat-affected zone (HAZ) 60% narrower than traditional TIG welding, with peak temperatures 300–400°C lower. This results from the fiber laser system’s concentrated energy distribution and rapid cooling rate.
• High-Speed Processing
  Fiber lasers achieve welding speeds up to 20 mm/s on 3 mm stainless steel, reducing dwell time and deformation. For example, a 3 kW fiber laser system using full-penetration welding on 3 mm 316L stainless steel reaches this speed, with deformation deviation controlled to ≤0.1 mm/m.

Selecting the appropriate fiber laser welding machine and optimizing its parameters are key steps to prevent burn-through and deformation during stainless steel plate welding. Welding machine models vary significantly in performance, and key parameter settings directly impact welding quality—critical for achieving optimal results.

Low-Power Models (1000W–2000W)

Low-power fiber laser welders (1000W to 2000W) suit high-precision applications requiring minimal heat input, ideal for thin stainless steel components or delicate welding. When welding 3mm sheets, their gentle heat source reduces burn-through risk. However, slower speeds may be needed for sufficient penetration, affecting productivity.

Medium-Power Models (2000W–4000W)

Medium-power systems (2000W to 4000W) balance power and precision, handling diverse stainless steel tasks—including 3mm plates. Compared to low-power models, they weld faster while maintaining penetration and quality, suitable for small-batch and medium-scale projects.

High-Power Models (4000W+)

High-power fiber lasers (4000W and above) target heavy-duty applications, quickly melting thick stainless steel. For 3mm sheets, they boost welding speed and efficiency. However, parameters must be tuned carefully to avoid overheating-induced burn-through and deformation.

1. Laser Power

Laser power directly determines heat input during welding. Higher power increases metal melting rate, aiding deep penetration. For 3 mm stainless steel plates, however, excessive power risks burn-through, while low power causes insufficient penetration and weld strength. Thus, selecting an appropriate power level based on specific welding requirements is critical—refer to preceding content for detailed settings.

3. Pulse Frequency

Pulse frequency determines the laser’s pulse emission rate, directly impacting weld seam consistency and thermal behavior during 3 mm stainless steel welding.

Optimal frequency range (50–200 Hz):
A frequency of 100–150 Hz forms continuous weld seams in 304 stainless steel while minimizing heat accumulation.

High-frequency risks (>200 Hz):
Frequencies over 200 Hz cause linear heat input increases. For example, welding 3 mm 316L steel at 250 Hz raises peak temperatures to 1550°C—approaching its melting point (1400–1450°C)—leading to 0.2 mm burn-through defects in 12% of samples.

Pre-welding Preparation

• Material Inspection: Inspect stainless steel plates for cracks or inclusions before welding, and remove defects promptly if detected.
• Equipment Calibration: Adjust the fiber laser welder’s focusing position to ±0.1 mm accuracy.

Calibration Cycle and Verification

Daily: Perform quick calibration using a focusing inspection card with a 20μm aperture.

Weekly: Conduct full-process calibration.

After calibration, test-weld a 3mm stainless steel plate. Weld penetration depth fluctuation must be ≤±0.2 mm.

Fixture Design: Customize fixtures with thermal insulation to control heat distribution.

In-Welding Operational Techniques

Start and Stop Power Ramping

Implement a 10% power ramp-up at the start of welding and a gradual 10% ramp-down at the end. This technique mitigates thermal shock by preventing abrupt heat fluctuations, which can cause cracking or burn-through at weld start/stop points.

Segmented Welding Protocol

Divide long weld seams into 50–100mm segments, interspersing each segment with cooling intervals. This approach reduces cumulative heat input, as validated by thermal imaging studies showing a 35% lower peak temperature in segmented vs. continuous welding of 3mm stainless steel.

Real-Time Thermal Monitoring

Deploy infrared (IR) thermal cameras to visualize temperature gradients across the weld zone. This allows immediate parameter adjustments.

On-Site Troubleshooting

Burn-Through Remediation
Upon detecting burn-through, take two corrective steps: first, reduce laser power by 10–15% to cut excessive heat input; then, increase welding speed by 15–20% to minimize dwell time in the affected area. For damaged sections, use compatible filler wire to restore structural integrity.

Deformation Rectification

• Mild Deformation(≤2mm deviation): Use hydraulic presses with calibrated force to mechanically straighten workpieces. Ensure even pressure distribution to prevent secondary damage.
• Severe Deformation: For significant warping, apply low-temperature flame annealing at 300–400°C—a range validated by ASME standards to relieve internal stress without compromising material properties. Combine annealing with fixture realignment to restore the metal to its target shape within precision tolerances.