NM400 cutting and welding methods
NM400 wear-resistant steel plate is a kind of heat-treated steel plate. Like most wear-resistant steel plates on the market, it is heated to a certain temperature. When the temperature is above 300 degrees, the hardness will drop rapidly. Therefore, when cutting, the wear plate should use cold cutting as much as possible, otherwise the problem of cutting hardness drop will occur.
NM400 wear-resistant plates are heat-treated and tempered steel plates, so most of them have been cut by plasma or other cutting methods. Flame cutting is to cut the wear plate with high temperature oxygen, so the flame cutting process will have a heat affected zone on the wear plate. Now, the flame-cut Abrasion 400 wear plate is still used. Generally, the hardness of the cut is not high when used. The problem of a decrease in hardness can be ignored. Because flame cutting can be cut edge-to-edge, material saving, and cutting costs are relatively low.
Cutting Methods for NM400
Cutting methods for NM400 wear-resistant steel plates can be divided into two main categories: cold cutting and hot cutting. Cold cutting includes waterjet cutting, shearing, sawing, or abrasive cutting; hot cutting includes oxy-fuel flame cutting (hereinafter referred to as "flame cutting"), plasma cutting, and laser cutting. The actual choice depends on the steel plate thickness, precision requirements, and tolerance for the heat-affected zone.
Comparison of Cutting Methods
| Cutting Method | Applicable Thickness | Heat-Affected Zone (HAZ) | Edge Quality | Cutting Speed | Recommendation Priority |
|---|---|---|---|---|---|
| Waterjet Cutting | ≤100 mm+ | None (cold cutting) | Excellent | Slow | ★★★★★ (high-value thick plates) |
| Laser Cutting | ≤20–30 mm | Very small | Excellent | Fast | ★★★★★ (thin plates, high precision) |
| Plasma Cutting | ≤50 mm | Moderate | Good | Fastest | ★★★★☆ (preferred for batch production) |
| Flame Cutting | No strict limit | Large | Rough | Slow | ★★☆☆☆ (use with caution) |
- Laser Cutting: Laser cutting is suitable for cutting NM400 wear-resistant steel plates, especially for high-precision cutting of thin plates (≤20mm) and processing of complex contours. Laser cutting results in a very small heat-affected zone (approximately 0.2mm), excellent edge quality, and typically allows for direct entry into subsequent processes without secondary treatment.
- Plasma Cutting: Plasma cutting is the best cost-effective option for batch production of NM400 wear-resistant steel plates. Underwater plasma cutting is recommended for cutting high-grade wear-resistant steel. Underwater cutting effectively absorbs excess heat and significantly reduces the heat-affected zone, making it one of the most widely used cutting methods in industrial production.
- Waterjet Cutting: Waterjet cutting is the only cutting process that completely eliminates the heat-affected zone. There is no thermal deformation during the cutting process, and the cut edges completely retain the original hardness and toughness of NM400. Although the cutting speed is relatively slow and the cost is higher, waterjet cutting is the preferred solution for thick plates exceeding 50mm or high-value core components with strict fatigue life requirements.
- Flame cutting: The flame cutting method for high-grade wear-resistant steel is as simple as that for ordinary low-carbon and low-alloy steel, but special care is required when cutting thick plates of wear-resistant steel. The key point is that as the thickness and hardness of the steel plate increase, the risk of cold cracking during cutting also increases. To ensure cutting quality, higher gas pressure and oxygen levels should be selected during flame cutting, while the cutting speed should be appropriately reduced.
Cutting and welding requirements
To fully utilize the superior properties of NM400 steel, strict adherence to correct welding, cutting, and forming processes is essential. These operational guidelines help maintain the steel's original high wear resistance, high hardness, and good toughness, while effectively reducing the risk of material damage during processing.
Key points for machining NM400 steel
Welding
For thick plates (≥20mm), preheat to 150–250℃ to prevent cracking.
Use low-hydrogen electrodes (e.g., E7018) to avoid hydrogen-induced cracking.
Control heat input, keeping interpass temperature below 150℃ to prevent softening.
Use straight weld beads to minimize the heat-affected zone.
Cutting and Shaping
Plasma or laser cutting is preferred for better cuts and less deformation.
Cold bending is preferred; the bending radius must match the plate thickness to avoid heating.
Post-Weld Heat Treatment
PWHT stress relief can be performed, but care must be taken to avoid reducing hardness due to excessive temperature.
Drilling/Machining
Use carbide or high-speed steel tools at low speed with adequate lubrication.
Clean the surface of rust and oil before welding.
Control the temperature throughout the process to avoid overheating and performance degradation.
Proper processing can maintain the wear resistance, hardness, and toughness of NM400, extending equipment life and reducing maintenance costs.
🛒 Contact Us for NM400 Cutting and Welding Services
✅ Abundant Inventory: Original NM400/NM400D/NM400E grade wear-resistant steel plates from leading steel mills such as Baowu, Ansteel, and Nanjing Steel, with thicknesses ranging from 6 to 100mm.
✅ Professional Cutting: We offer laser cutting, plasma cutting (including underwater cutting), waterjet cutting, and flame cutting services. Precise cutting according to drawings is possible.
FAQ:
What is NM400 steel?
NM400 Plates is a high-strength, wear-resistant steel known for its superior durability and toughness. NM400 is a Chinese GB standard steel grade. The NM 400 material is widely used in industries where resistance to abrasion (abrasion resistant) is important, such as in the construction and mining sectors.
Which is better, NM400 or AR400?
Neither is always better. The right choice depends on hardness, toughness, thickness, processing, and project specifications.
Is AR400 an ASTM grade?
AR400 is usually a market name for 400 Brinell abrasion-resistant steel plate, not one fixed ASTM grade.
What should I check before using NM400 instead of AR400?
Check hardness, chemistry, toughness, thickness, welding, bending, and the mill test certificate.