Laser Marking Application Case: Color Marking on Carbon Steel
Laser Marking Application Case: Color Marking on Carbon Steel
Equipment Configuration: Chuangxin MFPT Series MOPA 60W Fiber Laser
Color marking is generally considered an application exclusive to stainless steel and titanium alloys, but MOPA lasers can also produce unique color effects on carbon steel. Although the color range on carbon steel is not as rich as on stainless steel, tones such as brown, gold, blue, and purple can still be achieved, making it suitable for differentiated identification of tools, hardware, and other products.
I. Color Marking Principle
The principle of color marking on carbon steel is also the thin-film interference effect—the laser forms an oxide film on the surface, and different thicknesses of the oxide film interfere to produce different colors.
Differences from stainless steel:
- Carbon steel contains carbon, which interferes with color purity during the oxidation process
- The color range on carbon steel is narrower than on stainless steel, with warm tones (gold, brown, purple) being easier to achieve and cool tones (blue, green) being more difficult
- Cast iron is essentially incapable of color marking (graphite precipitation severely interferes with color)
II. Equipment Configuration
| Item | Parameter |
| Laser Source | Chuangxin MFPT Series MOPA Pulsed Fiber Laser (60W class) |
| Wavelength | 1066±3nm |
| Repetition Rate | 1-4000 kHz |
| Pulse Width Adjustment Range | 2-500 ns |
| Peak Power | Up to 10kW |
| Cooling Method | Air-cooled |
III. Parameter Reference
The parameter window for color marking on carbon steel is narrower than on stainless steel. The following are reference starting values.
Common Color Starting Parameters
| Color | Power | Speed (mm/s) | Frequency (kHz) | Pulse Width (ns) | Hatch Spacing (mm) | Defocus Amount |
| Gold | 70-90% | 500-800 | 40-60 | 80-150 | 0.01-0.02 | -0.5~-0.8mm |
| Brown | 60-80% | 300-600 | 30-50 | 100-200 | 0.02-0.03 | -0.3~-0.5mm |
| Blue | 80-100% | 400-600 | 70-90 | 50-100 | 0.01-0.02 | -0.3~-0.5mm |
| Purple | 70-90% | 400-700 | 50-70 | 50-100 | 0.01-0.02 | -0.3~-0.5mm |
Honest word on carbon steel color marking: The repeatability and consistency of color marking on carbon steel are not as good as on stainless steel. If the customer needs stable color effects, stainless steel or titanium alloy is the preferred recommendation. Carbon steel is more suitable for “warm-tone decorative effects” rather than precise color control.
IV. Effect Characteristics
- Color Range: Primarily gold, brown, and purple; blue is difficult to achieve stably
- Saturation: Not as vibrant as on stainless steel, leaning toward a “matte feel”
- Consistency: Color response varies significantly between different batches of carbon steel
- Surface Requirements: The smoother and more polished the surface, the better the color effect
V. Precautions
- Carbon steel grade has a significant impact: Low-carbon steel produces better color marking results than medium or high-carbon steel, as lower carbon content causes less color interference
- Surface preparation: Thorough derusting and degreasing are required before color marking, otherwise colors will be uneven
- Batch consistency: Batch variations in carbon steel have a significant impact on color; each batch requires re-sampling and confirmation
- Cast iron is not suitable: Cast iron has high carbon content (>2%), making color marking essentially unfeasible
- Practical business advice: If a customer requests color marking on carbon steel, it is recommended to create samples first to confirm the results and manage customer expectations
- High-end tool brand decorative identification
- Hardware product differentiated logos
- Carbon steel craft decorations
- Tool brand identification (gold/brown effects)
VI. Application Scenarios
Summary: Carbon steel can produce warm-tone color effects with a MOPA 60W, but the color richness and stability are not as good as on stainless steel. If the customer needs color, switching to stainless steel is the best option. If carbon steel is the only option, gold and brown are the more reliable choices.
*Color marking on carbon steel is sensitive to material and surface condition. Be sure to create samples for confirmation first.*
