Raex® 400 or Hardox® 400: Which one should you choose?

Raex® 400 and Hardox® 400 are two types of wear-resistant steel that are very similar, but not entirely the same. In this blog, we compare the composition and important properties of both materials and explain where the differences lie.

First, we will compare the following components:

• Chemical composition

• Mechanical properties

• Bendability: Minimum internal radius

• Weldability: Carbon equivalent

At the end, we give you general advice.

Chemical composition

Mechanical properties

The above shows the notch impact value and hardness for each type of material. Hardox® publishes values that are applicable within plate thicknesses of 2 to 130 mm. Raex® remains within 3 to 80 mm.

The notch impact value shows that Hardox® 400 is tougher at -40°C with 45 joules than Raex® 400, which scores 'only' 30 joules. In terms of hardness, both metals have an average of 400 HB. However, the margin is slightly larger for Raex® 400. This is not always desirable, particularly from the point of view of consistency and durability.

Looking at the notch impact value, Hardox® 400 performs better than Raex® 400. Important nuance: in the Netherlands, Belgium, and Germany, temperatures as low as -40° are not normally encountered, and J2 grades (27 joules at -20°) are sufficient. In these countries, both types of steel are normally perfectly adequate.

Looking at hardness, and especially the possible deviation, we can conclude that Hardox® 400 offers more certainty than Raex® 400.

Bendability: Minimum internal radius

The table above shows the minimum bending radius for each type of material per sheet thickness and rolling direction (90° is perpendicular to the rolling direction, 0° is parallel to the rolling direction). What is particularly striking is that Raex® 400 gives one average (3 x the plate thickness or 4x the plate thickness) and says nothing about the minimum bending radii for plates thicker than 20 mm.

But below 20 mm? There, the values of both materials are virtually identical, with Hardox® 400 having a slight advantage for plates thinner than 8 mm. 

Weldability: Carbon Equivalent

The table above shows the Carbon Equivalent (CEV) of both metals. The higher this number, the more challenging it is to weld the material. This is because welding increases the risk of embrittlement in the heat-affected zone (HAZ). This may not seem like a problem, but a more brittle metal is more susceptible to cracking and breaking. Therefore, the welding process must be carried out with such care that it limits embrittlement.

You can see that Hardox® 400 is slightly more weldable than Raex® 400 at thinner plate thicknesses. The latter, on the other hand, performs better with thicker plates. 

However, there is a 'but' in this story. In general, the limit for good weldability is set between 0.43 and 0.45. A lower value is relatively easy to weld. A higher value is relatively poor. Both materials are at or above the limit. Whichever metal is preferred, both are difficult to weld. It is therefore not surprising that welded joints in wear-resistant steels are preferably avoided and alternative joining methods are used.

Raex® 400 or Hardox® 400?

Our conclusion is that both steel grades have comparable wear resistance and mechanical performance. The workability of both grades also overlaps for the most part. Differences are mainly in small details and extremes. In most cases, you can therefore choose either one. 

But…

• ...does budget play a role? Then Raex® 400 is generally more economical.

• ...will the steel be used in regions with temperatures down to -40°C? Then Hardox® 400 is more suitable than Raex® 400.

• ...do you want the most consistent quality possible? Then the tolerances of Hardox® 400 are better suited to this.

• ...does the steel still need to be welded? Then consider Hardox® 400 for thin plates and Raex® 400 for thick plates.

Finally:

The averages provide a good basis for comparison. However, if you want to be sure of specific properties, you or the metalworker should always check the certificate for a specific batch. 

Do you have any questions?

Feel free to use this article as a reference. Do you need to choose a wear-resistant steel grade for your project? Then consult a metallurgist or structural engineer.

Do you have any questions about Raex® 400 or Hardox® 400? Feel free to contact us.

This article was written in collaboration with MCB. The figures used are taken from Hardox® 400 and Raex® 400 datasheets. Please refer to that documentation for the most up-to-date figures.