Laser Marking Application Case: Black Marking on Carbon Steel
Laser Marking Application Case: Black Marking on Carbon Steel
Equipment Configuration: Chuangxin MFP-50W Fiber Laser
Black marking on carbon steel is easier than on stainless steel—carbon steel naturally absorbs light well, and the black marks produced with a 50W laser are very rich in color with excellent visual effect. If your customer needs deep black, high-contrast marks, black marking on carbon steel is one of the most cost-effective options.
I. Black Marking Principle
The principle of black marking on carbon steel is similar to that on stainless steel: the laser heats the surface to form a dense Fe₃O₄ oxide layer that absorbs visible light, appearing black. However, carbon steel has a higher iron content and the presence of carbon, so the oxide layer forms faster and is thicker, making black marks easier to achieve.
II. Equipment Configuration
| Item | Parameter |
| Laser Source | Chuangxin MFP-50W Acousto-Optic Q-Switched Pulsed Fiber Laser |
| Wavelength | 1064nm |
| Repetition Rate Range | 45-170 kHz |
| Pulse Width | ~100ns |
| Cooling Method | Air-cooled |
III. Parameter Reference
Recommended Starting Parameters
| Parameter | Recommended Value | Notes |
| Power | 40-60% | Carbon steel black marking does not require very high power |
| Speed | 200-500 mm/s | Slow speed ensures sufficient oxide layer formation |
| Frequency | 20-30 kHz | Low frequency increases single-pulse energy |
| Hatch Spacing | 0.03-0.06mm | Moderate is sufficient |
| Fill Method | Unidirectional fill | More uniform oxide layer |
| Number of Passes | 1-2 | 2 passes can deepen blackness |
Parameter Comparison with Stainless Steel Black Marking
| Comparison | Stainless Steel Black Marking | Carbon Steel Black Marking |
| Power | 50-75% | 40-60% |
| Speed | 100-300 mm/s | 200-500 mm/s |
| Ease of Black Marking | Requires fine tuning | Easy, wide parameter window |
| Blackness Depth | Deep black | Rich deep black |
| Time per Piece | Longer | Approximately 1.5-2 times faster than stainless steel |
IV. Effect Characteristics
- Color: Rich deep black, slightly matte texture
- Contrast: Extremely high, strong contrast with carbon steel substrate
- Feel: Slight tactile sensation
- Wear Resistance: Good, but carbon steel itself may rust; the marked area needs attention if exposed to humid environments for extended periods
V. Precautions
- Carbon steel grade differences: High-carbon steel produces deeper black marks than low-carbon steel, as higher carbon content contributes to black formation
- Rust prevention: The black marked area, due to the laser heating that changes the surface state, may be more prone to rusting than the surrounding area. It is recommended to apply anti-rust oil or other rust protection after marking
- Surface condition: Rusted carbon steel must be derusted before black marking, otherwise the blackness will be uneven
- Thin sheets: When black marking thin sheets below 1mm, pay attention to heat control to prevent deformation
- Hardware tool brand identification
- Mechanical component marking
- Carbon steel mold numbering
- Construction hardware logos
- Industrial valve / pipe fitting identification
- Tool / cutter brand marking
VI. Application Scenarios
Summary: Black marking on carbon steel is the “specialty” of the 50W fiber laser—easier than on stainless steel, with better results and faster speed. The parameter window is wide, and good results can be achieved without overly fine tuning. The only thing to remind customers about is rust protection.
*It is recommended to create samples before batch production, especially since different grades of carbon steel produce varying results.*
