Stainless Steel Laser Welding Guide

Why Stainless Steel Laser Welding Needs a Clear Window

Stainless steel is one of the most common welding materials in sheet-metal manufacturing: enclosures, kitchen equipment, cabinets, machine covers, and structural brackets. On thin sheet (0.5–3 mm), the main challenge is not penetration, but keeping the weld strong and clean without burning through.

Unlike mild steel, stainless has lower thermal conductivity and a relatively narrow comfort zone between “not fully fused” and “over-heated blue/black welds”. A fiber laser gives you very fine control — but only if power, scanning and shielding gas are kept inside a stable window.

Process Basics – Gas, Focus and Scanning Strategy

Shielding Gas and Air Flow

For stainless steel thin sheet, we recommend:

Gas: Nitrogen (N₂)
Flow: ≥ 20 L/min
Mode: Continuous flow during welding

Nitrogen prevents oxidation and keeps the weld silver or light straw in color. Flows below 20 L/min tend to produce darker surfaces and occasional pores in fillet welds. Higher flow rates can improve protection on large fillets or deep V-grooves, but also increase gas consumption, so we recommend validating the range on your parts.

Focus Position

For 0.5–4.0 mm stainless sheet we use a focus position of 0 mm (focus on surface). This gives a good compromise between penetration and tolerance to small height variations on industrial parts.

• Focus < 0 mm (into the material) → more penetration, higher risk of blow-through on 0.5–0.8 mm sheet.
• Focus > 0 mm (above surface) → wider, shallower welds; useful for cosmetic beads but weaker roots.

Scanning Frequency and Scan Width

Instead of a static spot, M-Series welders use an oscillating beam. Two variables control how the energy is distributed:

• Scanning frequency (Hz) – how fast the beam moves within the weld pool.
• Scan width (mm) – how wide the oscillation pattern is.

In general:

• Thin sheet (0.5–1.0 mm): higher frequency (up to 150 Hz), narrower width (1.5–2.5 mm) to avoid melt-through.
• Mid-thickness (1.2–2.0 mm): 60–100 Hz with ~3 mm width balances penetration and surface appearance.
• Thicker sheet (2.5–4.0 mm): lower frequency (25–40 Hz), wider width (3.5–4.5 mm) to keep a stable pool.

Thickness-Based Strategy – How to Use the Window

0.5–1.0 mm Stainless – Avoiding Burn-Through

• Start from the 0.5–1.0 mm rows in the tables above.
• Keep scanning frequency high (100–150 Hz) and scan width ≤ 2.5 mm.
• Prefer 1200 W at lower %, rather than 800 W at high % if you need extra headroom.

If you still see blow-through at corners or gaps, first increase scanning width by 0.2–0.5 mm, then reduce peak power in 2 % steps.

1.2–2.0 mm Stainless – Main Production Range

Most industrial enclosures and sheet-metal frames fall in this band. Here the goal is stable penetration with a narrow, cosmetic weld.

• Use 1.2–2.0 mm rows: 40–45% peak power at 60–100 Hz, 3.0–3.5 mm width.
• For fillet welds in corners, reduce travel speed slightly or increase peak power by 2–3 %.
• For butt joints with tight fit-up, keep scan width at 3 mm to avoid excessive crown.

2.5–4.0 mm Stainless – Deep Penetration

At 2.5–4.0 mm thickness, you are approaching the limit of single-sided welding on 800–1200 W systems, especially on wide gaps or large fillets.

• Increase peak power to 65–75 % and lower scanning frequency to 25–40 Hz.
• Use 4.0–4.5 mm scan width to keep a stable, wide melt pool.
• On 800 W, keep 3.0 mm as a realistic ceiling for full-penetration welds; thicker parts may require double-sided or multi-pass welding.

Typical Weld Defects and How to Correct Them

Burn-Through on 0.5–0.8 mm Sheet

Symptoms: holes at starts/stops, severe undercut, edge collapse on overlapped joints.

Corrections:

• Increase scanning frequency towards 150 Hz.
• Increase scan width by 0.3–0.5 mm.
• Reduce peak power in 2 % steps until the root is just complete.

Dark Blue / Black Welds

Symptoms: continuous dark coloring, especially near the toe of the weld.

• Check nitrogen flow (aim for ≥ 20 L/min at the nozzle).
• Verify nozzle stand-off and alignment; excessive distance breaks the gas shield.
• If gas is correct, slightly reduce peak power or scanning frequency to lower heat input.

Lack of Fusion at the Root

Symptoms: weld looks fine on the surface but fails bend tests or shows incomplete penetration on cut sections.

• Increase peak power by 3–5 %.
• Reduce travel speed slightly (or reduce wire feed rate while keeping power constant).
• On fillet welds, reduce scan width by 0.5 mm to concentrate energy.

Example – Switching from TIG to Laser on 1.5 mm Stainless Cabinets

A typical thin-sheet application is 1.2–1.5 mm stainless cabinets and covers. Below is a simplified example based on common production data.

• Material: 1.5 mm 304 stainless sheet.
• Previous process: manual TIG welding, ~150 mm/min effective speed, significant post-grinding.
• Laser setup: 1200 W, 1.5 mm table row, nitrogen ≥ 20 L/min, focus 0 mm.

Using the 1.5 mm row from the 1200 W table (13 mm/s wire feed, 40% peak power, 60 Hz, 3 mm width) the shop achieved:

• 3–4× higher welding speed on straight seams.
• Minimal discoloration – most parts required no grinding.
• Lower heat input → less distortion, easier fit-up in final assembly.

For plants already using GWEIKE cutting machines, the M-Series 6-in-1 platform lets the same crew add laser welding without a steep learning curve. Parameters in this guide are designed as a direct starting point for operator training.

Related Process Guides and Parameter References

For a complete process library around stainless steel and thin-sheet work, see:

• Handheld Laser Cutting Safety Parameters – Gas Pressure, Peak Power and PWM
• Handheld Fiber Laser Cutting Troubleshooting Guide
• Laser Bevel Cutting Guide: Plate & Tube in One Pass – Process Window, QA & ROI
• Industrial Aluminum Laser Welding Guide

Together with this stainless steel welding guide, these articles form a practical parameter window library covering cutting, welding and bevel preparation for stainless, carbon steel and aluminum.

FAQ – Stainless Steel Laser Welding