Hardox 400 vs 450 vs 500: Which Wear Plate Should You Choose?

What is Hardox, and why does the right grade matter?

Short answer: Hardox 400 is the general-purpose grade and the easiest to work, Hardox 450 is the best all-round choice for most applications, and Hardox 500 gives the longest life under heavy abrasion. The right choice sets both the service life of the part and the fabrication cost in the workshop.

Hardox is the quenched and tempered wear plate brand of Swedish steelmaker SSAB. It launched in 1974 as the world's first bendable wear steel. The number after the name is the nominal Brinell hardness (HBW): 400, 450 or 500.

Higher hardness means longer wear life. It also means bending, welding and cutting need more care. So "the hardest plate is the best plate" is not always true. In this article we compare the three grades with real figures and explain which one to choose for each situation.

Hardox 400 vs 450 vs 500 at a glance

The key difference between the three grades is hardness. Each 50 HBW step extends wear life noticeably, but bending and welding need more care.

Hardox 400

• Hardness: 370 – 430 HBW
• Plate thickness: 4 – 130 mm (sheet: 2 – 8 mm)
• Typical yield strength: 1100 MPa
• Typical impact energy (Charpy V, −40 °C, 20 mm): 45 J
• Bendability: Easiest
• Welding: Very easy, no preheating needed up to 20 mm
• Wear life: Reference grade
• Typical use: Moderate wear, parts with a lot of forming

Hardox 450

• Hardness: 425 – 475 HBW
• Plate thickness: 3.2 – 160 mm (sheet: 2 – 8 mm)
• Typical yield strength: 1250 MPa
• Typical impact energy (Charpy V, −40 °C, 20 mm): 50 J
• Bendability: Easy
• Welding: Easy
• Wear life: 30 – 40% longer than Hardox 400
• Typical use: Buckets, dump bodies, containers, general heavy duty

Hardox 500

• Hardness: 470 – 530 HBW
• Plate thickness: 4 – 103 mm (sheet: 2 – 7 mm)
• Typical yield strength: 1400 MPa
• Typical impact energy (Charpy V, −40 °C, 20 mm): 37 J
• Bendability: Needs a larger bending radius
• Welding: Needs more preheating and control
• Wear life: Longest of the three
• Typical use: Crushers, chutes, heavy sliding wear

Notes: Hardness values apply to thicknesses up to 32 mm. The lower hardness limit drops slightly for Hardox 450 above 80 mm and for Hardox 500 above 32 mm. Yield and impact values are typical values from SSAB, not guaranteed. Hardox plates are through-hardened; core hardness is at least 90% of the guaranteed minimum hardness.

Source: SSAB datasheets for Hardox 400, Hardox 450 and Hardox 500 (ssab.com).

A closer look at each grade

Hardox 400: The easiest wear plate to fabricate

With a nominal hardness of 400 HBW, Hardox 400 is known as the workhorse of the family. In the workshop it behaves much like structural steel such as S355. It can be welded with ordinary consumables, and no preheating is needed for welding up to 20 mm. It bends to tight radii and can be drilled and machined with standard tools.

When to choose it: When wear is moderate and the part involves a lot of bending, welding or machining. It is common in road building, agricultural machinery, concrete and cement equipment, recycling and quarrying.

Hardox 450: The industry standard

Hardox 450 is the best-known wear plate in the world. It adds 50 HBW of hardness over Hardox 400 while keeping toughness at a similar level. According to SSAB's calculations, moving from Hardox 400 to 450 increases wear life by 30 – 40%.

The extra hardness can be used in two ways: longer life at the same thickness, or the same life with thinner plate. The second option makes equipment lighter; tipper and body builders save hundreds of kilograms this way.

When to choose it: When abrasion and impact occur together. Excavator and loader buckets, dump bodies, scrap containers, concrete mixers, crushers and chutes are typical applications.

Hardox 500: Long life under heavy abrasion

With a nominal hardness of 500 HBW, Hardox 500 gives the longest life under heavy sliding wear. Its typical yield strength is 1400 MPa. On the other hand, its impact toughness is lower than 400 and 450, it needs a larger bending radius, and it requires preheating for welding at smaller thicknesses.

When to choose it: On surfaces where abrasive material such as sand, ore or crushed rock slides continuously. Crusher liners, feed chute bottoms, screens and hopper linings are examples. If the part also takes heavy impact, consider Hardox 500 Tuf, which combines the toughness of 450 with the hardness of 500.

Which one should I choose? A quick decision guide

If in doubt, start with Hardox 450; it offers the best balance of wear life and workability for most heavy-duty applications. Use the guide below for your situation.

• Many bends and welds, moderate wear: Hardox 400. The easiest grade to fabricate, with lower labour cost.
• Abrasion and impact together (buckets, dump bodies, containers): Hardox 450. The best balance of life and toughness.
• You want lighter equipment: Hardox 450. The extra hardness gives the same life with thinner plate.
• Continuous sliding wear, little impact (chutes, hoppers, crusher liners): Hardox 500. The longest wear life.
• Heavy abrasion and heavy impact: Hardox 500 Tuf. 500 hardness with 450 toughness.
• Budget first, flat plate lining: Hardox 400 or equivalent grades. Lower material cost.

Look at the total life of the part, not only the plate price. A more expensive grade can cost less overall by reducing replacements and downtime.

How to cut and bend Hardox

The most important rule with Hardox is temperature control. Hardox gets its hardness from quenching; areas heated above 250 °C lose their as-delivered properties. That is why the cutting and bending method should match the thickness and the grade.

Cutting method by thickness

• Thin and medium plate – Laser cutting: Narrow heat-affected zone and the most accurate dimensions. Preheating is not recommended.
• Medium and thick plate, parts that need weld bevels – Plasma cutting: Bevel cuts and chamfers can be made in a single operation.
• Thick and very thick plate – Oxy-fuel cutting: The most economical method. Thick Hardox may need preheating.

According to SSAB, preheating reduces the risk of delayed hydrogen cracking at the cut edge. It is most useful for oxy-fuel cutting and plasma cutting with oxygen. For laser cutting and nitrogen plasma it is not recommended, because it harms edge quality. The required preheating temperature rises with grade and thickness: at the same thickness, Hardox 500 needs preheating earlier than Hardox 400.

Small parts and narrow strips cut from thick plate with oxy-fuel cannot shed heat and may soften. Laser or plasma is the better choice for these parts.

Bending

Hardox is a bendable wear plate, but the minimum bending radius grows with hardness. SSAB gives a bending guarantee class for each grade; Hardox 400 bends to the tightest radius and Hardox 500 needs the largest. Set the inner radius on your drawing according to grade and thickness. If you are unsure, ask our team before ordering.

Source: SSAB, Preheating before thermal cutting (ssab.com).

Hardox equivalents: Dillidur and NM450

Equivalent grades with the same nominal hardness give wear resistance close to Hardox. The differences show up in guarantees, toughness values and delivery time.

• Hardox 400 (370 – 430 HBW): Dillidur 400 (370 – 430 HBW, 6 – 150 mm) and NM400
• Hardox 450 (425 – 475 HBW): Dillidur 450 (420 – 480 HBW, 6 – 100 mm) and NM450
• Hardox 500 (470 – 530 HBW): Dillidur 500 (450/470 – 530 HBW, 8 – 100 mm) and NM500

Dillidur is the brand of Germany's Dillinger. It is a strong alternative, especially for thick plate. Through-thickness hardness and impact values are guaranteed on request.

The NM series is made to China's GB/T 24186 standard. The number shows the nominal Brinell hardness. It is usually more economical, but toughness and tolerance guarantees vary by mill. Always ask for hardness and impact test values on the certificate when ordering.

For critical, impact-loaded structural parts, choose original Hardox or Dillidur. For less critical uses such as flat linings, the NM series is a sensible cost choice.

Source: Dillinger, Dillidur product overview (dillinger.de).

Frequently asked questions

What is the difference between Hardox 400 and 450?

Hardox 450 is 50 HBW harder and, according to SSAB data, gives about 30 – 40% longer wear life. Its toughness is close to that of 400. Hardox 400 is easier to bend and weld.

Is Hardox 500 always the best choice?

No. Hardox 500 gives the longest wear life, but its impact toughness is lower and bending and welding need more care. For impact-heavy applications, Hardox 450 or Hardox 500 Tuf is a better fit.

Can Hardox be laser cut?

Yes. Laser cutting keeps the heat-affected zone narrow, which makes it the preferred method for Hardox. Preheating is not recommended before laser cutting.

Can Hardox be welded?

Yes. Hardox 400 can be welded with standard consumables and without preheating up to 20 mm. For thicker plate and harder grades, follow the manufacturer's preheating table.

Can Hardox be heat treated?

No. Hardox gets its hardness from quenching at the mill. Above 250 °C it loses its as-delivered properties.

Is NM450 the same as Hardox 450?

Their nominal hardness is similar. However, Hardox comes with guarantees for thickness, flatness, bending and through-thickness hardness. With NM450, these values vary by mill.

Get your Hardox plate cut to size

Fabensan supplies wear plate, including Hardox, Dillidur and NM450, and cuts and bends it to your project. We laser cut up to 80 mm, plasma cut up to 60 mm with bevelled weld preps, and oxy-fuel cut up to 420 mm. Our press brakes bend parts up to 12 metres long.

There is no minimum order; we quote anything from a single prototype to series production.

1. Sign up at fabensan.com and upload your DXF, DWG, STEP or PDF drawing.
2. Choose the Hardox grade and thickness. If you are not sure, describe your application in the notes and our team will recommend a grade.
3. Get your quote and approve it; your parts are delivered cut and bent to your door.