S355J0 (EN10025-2), low-alloy high-strength steel with moderate carbon equivalent. Prevent delayed cutting cracks for plates thicker than 30mm. The table below shows standard parameters for CNC oxy-fuel cutting machine with acetylene fuel (G02 cutting nozzle). If propane fuel is adopted, fuel gas pressure can be increased by 0.02~0.03MPa.
1. Standard Parameter Table by Plate Thickness
Flame requirement: Neutral flame. Distance between flame core tip and plate surface: 8～10 mm. Oxygen purity ≥99.5%
| Plate Thickness t(mm) |
Nozzle Size |
Cutting Oxygen Pressure (MPa) |
Acetylene Preheating Pressure (MPa) |
Cutting Speed (mm/min) |
Preheating Time before Ignition |
| 6～12 |
No.1 |
0.25～0.32 |
0.03～0.05 |
320～260 |
3～5s |
| 12～20 |
No.2 |
0.32～0.40 |
0.04～0.06 |
260～210 |
4～6s |
| 20～30 |
No.3 |
0.40～0.50 |
0.04～0.06 |
210～160 |
5～7s |
| 30～50 |
No.4 |
0.50～0.65 |
0.05～0.07 |
160～120 |
7～10s |
| 50～80 |
No.5 |
0.65～0.75 |
0.06～0.08 |
120～85 |
10～14s |
| 80～120 |
No.6 |
0.75～0.85 |
0.06～0.08 |
85～60 |
14～18s |
| 120～160 |
No.7 |
0.85～0.95 |
0.07～0.09 |
60～40 |
18～25s |
| 160～200 |
No.8 |
0.95～1.05 |
0.07～0.09 |
40～28 |
25～35s |
2. Exclusive Key Process Requirements for S355J0 (Critical to Avoid Cutting Cracks)
- Pre-cutting Preheating (Prevent Delayed Cold Cracks)
- t ≤25mm: Cutting can be performed at ambient temperature; local preheating to 50~80℃ is recommended when ambient temperature ＜5℃.
- t ＞25mm: Mandatory preheating to 100～120℃ (range ≥100mm on both sides of cutting line).
- t ≥60mm / low temperature in winter: Increase preheating temperature to 120～150℃.
- Flame Specification Carburizing flame is strictly prohibited (causes carburization, hard cut edges and cracking). Slightly oxidizing flame is acceptable.
- Post-cutting Treatment Forbid forced air cooling or water quenching immediately after cutting thick plates. Stack workpieces for slow cooling down to room temperature. Remove slag and hardened layer on cutting surface by grinding if welding follows cutting.
- Guidelines for Internal Hole Cutting Drill pilot holes for piercing when cutting internal holes of thick plates; avoid direct piercing. Reduce travel speed and extend preheating time during piercing.
3. Troubleshooting for Common Defects
- Adherent dross / incomplete cut: Insufficient oxygen pressure or excessive cutting speed.
- Overheated edge, edge collapse & rough cutting texture: Excessive oxygen pressure or too low cutting speed.
- Micro-cracks on cutting face: Insufficient preheating or rapid cooling. Increase preheating temperature as priority solution.
- Uneven kerf width: Check cutting torch verticality and nozzle blockage.
Cutting processing: wear-resistant steel plates (NM360/NM400/NM450/NM500/Mn13), high-strength plates (Q690D/E/S690Q/QL), ordinary plates (Q235B/S235JR), low alloy plates (Q355B/C/D/E/S355JR/J0/J2/K2), carbon bonded plates (45 #, S45C, S50C, bm48c), as well as various special alloy steels from large steel mills such as Wuhan Iron and Steel Group, Liangang, Baosteel, Ansteel, Shagang, Nangang, Hanye, Xingcheng, Yingkou, Ma Steel, etc., as well as Tang Steel, Wenfeng, Ping Steel, etc. The specification is 6MM-500MM thick.
We have good business channels with major steel mills and undertake various types of steel plate OEM processing business. The processing center can cut various supporting materials for engineering machinery, metallurgical equipment, mining machinery, etc. according to customer requirements, such as square plates, circular cakes, flanges, machine side plates, irregular parts, bearing support seats, etc., and process various irregular parts, support seats, machine tool side plates, metallurgical mines, and other supporting materials
