CNC machining AR400-Ultimate Guide 2024

Updated: Jan. 25, 2024

Recently customers sent us some projects with AR400 material CNC machining parts. After consulting several material suppliers we commonly use, as well as in China’s commonly used website Taobao, trying to search for AR400 material, there are no results. Is AR400 a rare material? After several days of research and discussion with our engineers, we finally figured out what AR400 is and AR400 CNC machining considerations.


The purpose of this article is help you to understand the AR400 situation in China and give some information about AR400 CNC machining information. Let’s learn together.

1. What is AR400?

AR400 is a group of wear-resistant steel with hardness up to 400HBW. The AR in AR400 is the abbreviation of the phrase abrasion resistant. 400 refers to the average Brinell hardness of this kind of steel, the general hardness range of AR400 is between HBW370-HBW430.


What is abrasion-resistant steel? Wear-resistant steel, also known as AR steel, is primarily used in applications where wear is the cause of failure. Typical uses include buckets and other heavy equipment attachments, dump and trailer bodies, concrete mixers, dump trucks, wear liners, and wear parts such as cutting edges.


AR steel plates are made from steel sheets containing different alloys. Among these alloys, carbon plays a key role in making wear-resistant plates as it increases the hardness of the steel. When the carbon content increases, the hardness increases, but the toughness decreases, making it more prone to cracking.


2. What is the equivalence of AR400 in China?

As mentioned earlier, AR400 is just a generic term for a class of wear-resistant steel with a hardness up to 400HBW, not a specific model. Different manufacturers produce this type of steel with different model numbers. For example, the AR400 wear steel produced by SSAB is Hardox® 400. Later in this article, we will introduce more manufacturers of wear-resistant steel.


In China, the equivalent of AR400 is NM400, which is short for NaiMo. Naimo in Chinese means the same as abrasion resistant in English.


3. Technical Parameters of AR400/NM400

Take the AR400 produced by SSAB as an example, the following are its technical parameters.

Hardox 400 sheet0.079 – 0.315370 – 43033 ft-lbs / -40°F
Hardox 400 plate0.157 – 5.118370 – 430

4. What are the properties of AR400/NM400?

Good wear resistance

The wear resistance of AR400/NM400 is 3-5 times higher than that of ordinary low alloy steel plates. This is mainly due to its own relatively high strength.


Excellent welding performance

The welding performance of the AR400/NM400 wear-resistant plate is not much different from that of ordinary 345B steel, and ordinary welding equipment can complete the welding of its wear-resistant plate.


Easy processing

AR400/NM400 is easy to process, including cutting, punching, bending, and chipping.


5. Applications of AR400/NM400 wear plate

AR400/NM400 is mainly used as a lining plate in mechanical equipment to produce friction parts, greatly improving the service life of the equipment, protecting the normal operation of the equipment, reduce the loss of maintenance and downtime, but also commonly used as a yield strength of ≥800MPa high-strength structural steel use. Typical applications include the following.


Engineering machinery and equipment: loaders, bulldozers, pavers, excavators, bucket plates, side blade plates, bucket bottom plates, blades, rotary drilling rig drill rods.


Loading and unloading machinery and equipment: unloading mill chain plate, hopper steel plate, grapple edge plate, medium-sized automatic dump truck dump plate, dump truck body.


Construction machinery and equipment: cement pusher plate, concrete mixer plate, mixer building plate, dust collector plate.


Metallurgical machinery and equipment: iron ore sintering conveyor elbow, iron ore sintering machine steel plate, scraper steel plate.


Mining machinery and equipment: steel plate of ore and stone crusher, blade, blower, coal mining machine, coal mill, shield machine, etc.


Other machinery and equipment: sand mill cylinder, blades, all kinds of port machinery wear parts, bearing structural parts, railroad wheel structural parts, rollers


Thermal power equipment: coal mill steel plate, coal hopper, coal distribution pipe, coal distributor plate, coal unloading equipment steel plate.

AR400 Application

6. AR400/NM400 CNC machining considerations

The hardness of AR400/NM400 is over 40HRC. It has high hardness and is a wear-resistant material. When CNC machining, you need to pay attention to the following matters.


Tool selection

AR400/NM400 is a high hardness wear-resistant steel and requires a tool with high wear resistance and hardness. A coated carbide would be appropriate, such as TiN (Titanium Nitride) or TiAlN (Titanium Aluminum Nitride). Tools with a strong cutting edge can effectively cut the high-hardness surfaces of AR400/NM400.


Machining can be done with HSS drills, especially cobalt-alloyed HSS drills. A satisfactory service life of the drill can be achieved if the appropriate feed speed and drilling speed match are used.


Suitable cutting parameters

Too high a cutting speed may lead to premature tool wear, while too low a speed may lead to inefficient machining. Appropriate feed speeds help ensure cutting efficiency and reduce vibration and deformation during the cutting process. Control the depth of cut to avoid overloading the tool while ensuring quality machining. The depth of cut can be increased gradually, observing the cutting results and making adjustments as needed.


Cutting fluids

Wear-resistant steels are usually hard and therefore generate a lot of heat during machining. Use sufficient coolant to cool the workpiece and tool to prevent overheating.


Readers can visit the following two forums to see the actual parameters that people use in practical machining on the AR400.


AR400 CNC Machining in practicalmachinist

AR400 CNC Machining in cnczone

7. How to cut AR400/NM400 wear plate?

The delivery state of wear-resistant steel plate is divided into 1: Tempered state 2: Tempered state (Tempered state = Quenched + Tempered) . AR400/NM400 wear-resistant plate can be cut by ordinary flame cutting, or plasma cutting.


Flame cutting should follow the following minimum preheating temperature: plate thickness 30~50mm, 75°C (170°F); plate thickness 50~100mm, 100°C (212°F); plate thickness above 100mm, 150°C (302°F).

8. Other grades of wear-resistant steel plates

Wear-resistant steel plates are more than four times as wear-resistant as mild steel, and some common grades include AR400, AR450, AR500, and AR600.

 Hardness rangeWear resistanceApplication
AR400/NM400360-440 HBWGoodMining,construction,metallurgy
AR450/NM450420-490 HBWBetterExcavator blades and protective shields
AR500/NM500450-600 HBWHigherExcavator blades,protective shields
AR600/NM600570-640 HBWHighestCoal mines,slag fields

Below are world-famous wear steel manufacturers and the models of the AR they produce.

CompanyCountryAR GradesTypical Types
SSABSwedenAR400,  AR450, AR500Hardox®400,  Hardox®450, Hardox®500, Hardox®550, Hardox®600, Hardox® 500 Tuf
ArcelorMittalFranceAR400,  AR450, AR500Amstrong Ultra 400
Amstrong Ultra 450
Amstrong Ultra 500
Nippon SteelJapanAR400,  AR450, AR500ABREX 400
ThyssenKruppGermanyAR400,  AR450, AR500XAR 400
XAR 450
XAR 500
POSCOKoreaAR400,  AR450, AR500POSCO FORA400
BaosteelChinaAR400,  AR450, AR500B-HARD400
JFE SteelJapanAR400,  AR450, AR500JFE EVERHARD 400
Ansteel GroupChinaAR400,  AR450, AR500ANSTEEL WEAR 400

9. FAQ


9.1 What is the common AR400/NM400 thickness?

NM400 can be supplied in thicknesses as thin as 2mm and as thick as 130mm, generally in standard widths of 2000mm or 2500mm and in lengths of 5800mm or 6000mm, or in widths of up to 3350mm and lengths of up to 14630mm in case of flat rolled plates, in compliance with the EN10028 European Union standard.


9.2 What is the common AR400/NM400 internal and external surface hardness differences?

NM400 is divided into thin plate and thick plate according to different production processes.


The thickness of thin plate is 2.0mm-8.0mm, the hardness range is between HBW370-HBW430, the internal hardness of the plate is slightly lower than the surface hardness, but because of taking the whole quenching, the lower center hardness is guaranteed to be 90% of the lower surface hardness. This shows that the overall uniformity of Hummer 400 is very good, also represents its processing performance.


Thick plates are available in thicknesses from 4.0mm-130mm, again with hardnesses between HBW370 and HBW4300. Typical yield strengths for both thin and thick plates are 1100 MPA.The impact characteristics of NM400, tested at Charpy impact test v-type 10*10mm specimen longitudinal test typical impact energy, reached 45J/-40 degrees Celsius. This figure marks the low temperature environment, NM400 can maintain good mechanical properties.


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