NM400 VS AR400: How to choose?
In industries such as mining, construction, and manufacturing, choosing the right wear-resistant steel has a significant impact on equipment performance and lifespan. NM400 and AR400 are two common choices, frequently mentioned due to their excellent wear resistance and toughness. But which one is more suitable for your project? This article will delve into the differences between NM400 and AR400, comparing their characteristics, applications, and advantages to help you make an informed choice.
What Are NM400 and AR400 Steels?
Both NM400 and AR400 are high-strength, wear-resistant steels designed for harsh abrasion environments. They are commonly used in heavy-duty applications such as dump truck liners, excavator buckets, and crusher components.
NM400: NM400 is a Chinese standard wear-resistant steel (NM stands for "wear-resistant") with a Brinell hardness (HBW) typically ranging from 360 to 440. It is known for its balance of hardness, toughness, and cost-effectiveness, making it popular in Asia and elsewhere.
AR400: AR400 is a well-known wear-resistant steel, also with a Brinell hardness (HBW) of 360–440. It is a versatile, integrally hardened alloy steel widely used globally, particularly in North America, due to its excellent impact resistance and formability.
While these two steels have similar hardness levels, their composition, manufacturing processes, and performance differences make them suitable for specific applications.
Chemical composition comparison
While both are low-alloy martensitic wear-resistant steels, their alloying element proportions present notable differences.
| Element | AR400 (%) | NM400 (%) | Notes |
|---|---|---|---|
| Carbon (C) | 0.28 – 0.43 | 0.17 – 0.25 | AR400 has higher carbon, providing greater hardness |
| Manganese (Mn) | 0.70 – 1.00 | 1.20 – 1.50 | NM400's higher Mn content improves toughness |
| Chromium (Cr) | 0.80 – 1.25 | 0.30 – 0.80 | AR400's higher Cr enhances abrasion resistance |
| Nickel (Ni) | ≤ 0.25 | ≤ 0.25 | Similar levels |
| Molybdenum (Mo) | 0.20 – 0.40 | ≤ 0.20 | Slightly improves AR400 hardness and high-temperature strength |
| Iron (Fe) | Balance | Balance | Base metal |
From the composition perspective: AR400 features higher carbon and chromium content, which contributes to higher overall hardness and abrasion resistance. NM400 employs higher manganese content along with more balanced alloy design, placing greater emphasis on impact toughness and overall performance stability.
For comparison, it is worth noting that Hardox 400 (SSAB's premium brand) generally contains higher chromium and nickel content, contributing to better hardness and toughness, while NM400 maintains a balance between cost and performance.
Mechanical Properties Comparison
| Property | AR400 | NM400 | Notes |
|---|---|---|---|
| Hardness (HBW) | 360 – 440 (nominal 400) | 360 – 450 | Both are wear-resistant; NM400 slightly better in HAZ toughness |
| Yield Strength (MPa) | ≥ 965 – 1200 (varies by mill) | ≥ 950 – 1100 | AR400 generally exhibits higher yield strength |
| Tensile Strength (MPa) | ~1240 – 1350 | 1200 – 1500 | Comparable levels |
| Elongation (%) | 10 – 15% | 12 – 18% | NM400 has better ductility under impact |
| Impact Absorbed Energy (J) | 27 – 40 J | 35 – 50 J | NM400 demonstrates superior impact toughness |
AR400 offers higher hardness overall, making it more suitable for pure abrasive wear applications. NM400, while maintaining comparable hardness levels, delivers better toughness and impact resistance, making it ideal for high-impact environments.
Processing Characteristics
NM400: NM400 is known for its good weldability and machinability, and can be cut, bent, and welded using standard equipment. However, for thicker plates, preheating is recommended (e.g., 75–150°C depending on thickness). It is recommended to use carbide tools and control the cutting speed during machining.
AR400: Compared to harder grades such as AR500, AR400 is easier to weld and machine. AR400F enhances formability, thus reducing machining time and costs. However, care must be taken to avoid heat-affected zone (HAZ) issues during welding.
It is worth noting that AR400, especially AR400F, is better suited for complex machining, while NM400, although versatile, requires careful handling.
How to choose for different application scenarios
Scenarios Where AR400 Is Recommended
High Abrasion / Low Impact environments - such as pure sliding abrasion in chutes, hoppers, and material handling systems where rocks, ore, or coal slide continuously across the steel surface.
- ASTM Standard Compliance Required - for projects that require strict adherence to international standards, typically in export applications.
- Higher Hardness Zone Requirements - some AR400 products may achieve slightly higher hardness in localized zones (e.g., heat-affected zones, thicker sections).
Scenarios Where NM400 Is Recommended
Impact-Heavy Work Conditions - in mining equipment such as excavator buckets, crusher liners, and dump truck bodies subjected to falling rocks and repeated heavy impacts; NM400 offers superior toughness and impact resistance.
- Low-Temperature Environments - especially grades NM400D and NM400E, which guarantee Charpy impact values at low temperatures. Hebei HBIS developed NM400E-TL for -40℃ extreme cold regions-21. NM400 also delivers lower-temperature toughness and higher structural reliability in cold environments.
- High Fabrication Demand Projects - requiring extensive welding, cold bending, and cutting; NM400's easier processing reduces fabrication time and cost.
Application cases include excavator buckets, loader blades, side cutters, crusher liners, medium-speed coal mill liners, dust collector flues, and other wear-resistant components in metallurgy, coal, cement, power, and mining industries
Common Applications Overview
| Application | AR400 | NM400 |
|---|---|---|
| Mining buckets and liners | ✔️ Yes | ✔️ Yes |
| Crusher parts | ✔️ Yes | ✔️ Yes |
| Bulldozer blades | ✔️ Yes | ✔️ Yes |
| Dump truck bodies | ✔️ Yes | ✔️ Yes |
| Chutes and hoppers | ✔️ Yes | ✔️ Yes |
| Extreme wear / impact | ✔️ Preferred for high impact | ✔️ Preferred for impact-heavy |
| Cold climate operations | △ Limited data available | ★★ Recommended |
| Export projects | ★★ ASTM certification | △ Domestic orientation |
Cost and Availability
NM400: Often more affordable due to its production by Chinese mills like Ansteel and Baosteel. It's widely available in Asia and increasingly exported globally.
AR400: Typically more expensive, especially from premium brands like SSAB (e.g., Hardox 400). It's readily available in North America and Europe but may have higher procurement costs in other regions.
Takeaway: NM400 offers a better cost-benefit ratio for mid-budget operations, while AR400's premium quality may justify its cost for high-stakes projects.
How to choose?
When deciding between NM400 vs. AR400, consider the following:
Wear Environment: If your application involves high-impact loading (e.g., dump truck beds), AR400's impact resistance is ideal. For sliding abrasion or moderate impact (e.g., chutes or liners), NM400 is sufficient.
Fabrication Needs: Need complex bending or forming? AR400F is easier to work with. For straightforward fabrication, NM400's versatility shines.
Budget: NM400 is the better choice for cost-conscious projects, especially in Asia. AR400 may be worth the investment for premium performance.
Environment: In colder climates, NM400's low-temperature toughness is a plus. For extreme heat or impact, AR400 holds up well.
Whether your wear challenge favors abrasion control or impact survival - we supply both NM400 and AR400 steel plates to meet your project specifications dimensionally and economically.
Contact our technical specialists today to review your working conditions (wear type, impact severity, temperature range) and receive a complimentary grade recommendation with current pricing.
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.
Is Hardox 400 the same as AR400?
You get reliable and predictable wear performance over the steel's service life. Hardox® 400 is also covered by guarantees for thickness, flatness and bending performance.
Is AR400 stronger than AR500?
Here's how it stacks up: AR400 AR500: Due to its higher manganese content, AR500 is about 1.25 times harder (500 HBW) and offers better impact resistance than AR400. However, it is also more brittle, making it less formable. Its strength and corrosion resistance make it best suited for high-impact environments.
Can AR400 steel be bent?
Difficult to form: The greater the carbon content of the steel, the less it will bend to shape. AR400 is difficult to form and attempting to form commodity AR500 or higher is impractical. It will often crack if you try to bend it at all.