Hardox steels can be defined as a type of steel with high durability. Hardox steels are also resistant to wear and it is first developed by SSAB, a Swedish steel producer. Due to the fact that steels wear slowly under a high amount of mechanical stress, Hardox steel is commonly known as a wearing plate. Therefore, Hardox steels are especially appropriate for organizations performing gravel and sand handling operations, for instance, tippers and buckets of excavators in which Hardox steel is used to increase the lifetime.
In this online article:
- Properties of Hardox steels
- What is wearing?
- Processing of Hardox sheet
- Cutting of Hardox steels
- Hardox put
- Machining of Hardox
- Overview of Hardox sheet metal
Characteristics of hardox steels consist of high hardness, uniform flatness, and very high strength. Since much thinner sections can be produced without compromising the strength of the part, the overall weight of a plate is significantly reduced. Moreover, Hardox is a type of steel that manages to preserve its resistance against sudden impact even at very low-temperature values. This wear-resistant material is also very suitable for welding and machining, so, repairing with great convenience is possible when it is damaged.
The combination of high hardness, strength, and wear resistance enables the total weight of construction to be reduced by around 15%. By improving Brinell hardness value 50 points, the life cycle of the produced part is extended by around 50-80%.
Characteristics of Hardox steels:
Hardness: It is a fact that the materials with high hardness values are able to scratch materials having lower hardness. Since Hardox is extremely hard steel, metals, rubble, stones, gravel, and sand cannot easily scratch this type of steel. It can be easily said that the wear-resistant characteristics of Hardox are one of its superiorities. The high hardness value is not limited to the surface hardness, but also to the inner structure of the material.
Toughness: The combination of high toughness and high hardness is what makes the Hardox steel very special. It is very hard to deform Hardox steel due to its high toughness. Thus, this material is an excellent choice in construction projects where high levels of mechanical loads are present. Even if Hardox steel is subjected to heavy impacts, it will endure against plastic deformation.
Machinability: Along with its high hardness and toughness, the machinability of Hardox steels are quite satisfactory. Plates made out of Hardox are suitable for machining operations such as cutting, bending, and welding without losing anything from its features.
What is wearing?
Hardox steels are highly resistant to wear. In order to comprehend the properties of this material, the definition and the types of wearing phenomena are given in detail below.
Wear…
Wear is a type of plastic deformation occurring by scratching a relatively soft material with harder material. Some amount of material will definitely be detached from the surface of the part. A serious amount of wear occurs if such an incident repeats itself for a long time. Because of this, the material will surely lose its function in time.
Wear caused by sliding
Sliding of particles like gravel, stone, scrap metal or rock cause material to be scratched. When the right Hardox steel plate is chosen, these bad wearing effects will be minimized.
Wear caused by impact
Sudden impacts may also cause wearing in steel materials. In the case of an impact where an object hit the steel at certain angles, scratching occurs. This situation can cause detrimental consequences in the steel, however, the life cycle can be increased when the right Hardox steel material is used.
Wear caused by pinching
Pinching is a dangerous one and it has the strongest influence on the life cycle of the material. Pinching occurs when fragments of abrasives are pressed from a tight space and damages the surface of the steel. This problematic situation can be avoided with the usage of a strong Hardox steel plate as a structural material in a building.
Processing of Hardox Sheet
Hardening and tempering heat treatment processes are performed on Hardox steel. Steel gain superior properties with these heat treatment processes, however, carelessly applied further processes may cause the steel to lose them. When the necessary precautions and measures of protection are taken, it is quite safe to the mill, cut, bend, and weld Hardox steel.
Currently, 400/450/500/550/600/Hituf and Extreme types of Hardox steel are available on the market. Each type differs from another in bendability, hardness, welding practices, and toughness. In this article, only a general perspective about Hardox steels is given. If you desire to explore more about each specific type of Hardox steels, the necessary data you seek is present on SSAB official internet page.
Wear resistant parts coming from factory
Cutting operations of Hardox
It is not easy to cut Hardox steel due to its high hardness. Thermal energy has to be introduced in the cutting process of Hardox steel. Several options exist in thermal cutting such as plasma cutting, autogenous cutting, and thermal cutting. For wear parts, wear strips and wear tiles which are able to be placed in machines to size, Hardox cutting is interesting. A combination of the cutting process performed on Hardox wear-resistant plate steel with machining, bending and welding is possible for benefiting in construction projects.
An excessive amount of energy (heat) is generated during the autogenous cutting process of Hardox steel. This is dangerous since mechanical properties and especially hardness can be negatively affected due to heat which causes the temperature to rise if cooling is not performed. It is a fact that if a 30 mm Hardox plate in thickness is cut in a length less than 2 meters by using autogenous cutting, the hardness of that part drastically reduces. For this reason, plasma cutting and laser cutting should be preferred instead of autogenous cutting.
Crack generation is probable in thermal cutting processes. Yet, this problem is not hard to prevent. Decreasing the cutting speeds, cooling down the plate slowly after cutting, or applying preheating before cutting begins are some of the solutions that can be benefited against the cracking problem. In general, hard materials are more likely to suffer cracking.
We are an experienced team on plasma cutting, autogenous cutting, and laser cutting operations performed on Hardox steels and we are able to supply customized parts straight out of the factory. Check out the possibilities we present on metal plate processing and wear-resistant sample sheet metals.
Bending and setting of Hardox steel
Cold forming operations by machining can be done on these high strength, wear-resistant Hardox steels. To achieve high levels of quality in bending, some factors have to be considered carefully since it is a high strength material. Buckets, silos, hoppers, and other various construction projects require bent Hardox steels in intricate shapes.
Rule of thumb:
- Required force for bending increases as the strength of the material increases.
- After setting, strong steel recoils more than regular steel.
- The radius of the stamp and width of the groove must be greater as the steel gets stronger and harder.
Surface of the plate
If the plate is damaged or rusted, flexibility significantly decreases. These defects must be corrected before bending operation. Operators of the bending machine must perform bending at intervals to prevent the occurrence of cracking in steel. Workpiece breaks in bending direction if existing cracks continue to grow.
Radius of stamp
Stamp radius of Hardox 450/500 sheets of steel must be 4 times of plate thickness. In order to prevent damaging the punch, tools used for bending must be in the same hardness values or higher.
Spring back
Hardox 500 plates of steel which are relatively harder have a spring back ratio between 12-20% while this number for Hardox 450 which is softer in comparison with Hardox 500/600 is between 11-18%. In the guidance of these data, the material has to be bent more than the desired radius by considering the spring-back effect. Simulation of the edge of the metal plate is possible with Tosec. By using it, the optimum depth of bending in the stamp is achieved with convenience.
Machining of Hardox
Machining of Hardox steels is done by using high-speed steel tools and metal drills with high hardness. Tools are selected according to the machine technology available. Strong vibrational movements may occur during milling and drilling, due to the toughness of the material. Possible damage threats on tools, workpieces, or the machine therefore cannot be ignored. Reducing vibrations is crucial in the machining of Hardox steels properly. Following preventive actions should be done to overcome this problem:
- Small gap between drill and tool holder.
- Steady clamping of workpiece.
- Minimizing the gap between the drill bit and the spindle by using short drills.
- Stopping the feed before the drill has penetrated through the plate for a second turning the feed on again after clearance/elasticity is removed.
- Usage of high amount of coolant to reduce the frictional temperature on the workpiece.
Tosec owns various machines for tapping, drilling, and milling Hardox steel wear parts. So many parameters exist to describe milling extensively. Milling the wear workpieces is interesting for drilling, tapping holes, milling edges, welding of edge bevels in wear sheets.
Overview on Hardox wear resistant steel types
Overview on Hardox wear resistant steel types:
Hardox 400
- Thickness of plate 3-130 millimeters
- Brinell Hardness: 370-430
Hardox 450
- Thickness of plate 3-80 mm
- Brinell Hardness: 425-475
When cold formed highly wear-resistant steels are needed, these types of Hardox steels are used.
Conveyor and dredging belts, recycling installations, chutes, and dump trucks are some of the usage areas of these high wear-resistant plate steels. These are characterized by excellent weldability.
Hardox 500
- Thickness of plate 4-32 millimeters
- Brinell Hardness: 470-530
- Thickness of plate 32-80 millimeters
- Brinell Hardness: 370-430
Hardox 550
- Thickness of plate 10-50 millimeters
- Brinell Hardness: 525-575
These types of Hardox steels are utilized in the fabrication of parts where high resistance to wear is required.
These types are intensively used in gears of grinding equipment, breaker and knife teeth, and conveyor belts. If the temperature of these materials exceeds 250 °C, they will begin to lose their mechanical properties.
Hardox 600
- Thickness of plate 8-50 millimeters
- Brinell Hardness: 560-640
This type of Hardox steel is mainly used in construction projects where high wear resistance is needed. For example, chutes, shredders, and demolition hammers are products in which Hardox 600 is used.
Hardox HiTuf
- Thickness of plate 40-120 millimeters
- Brinell Hardness: 310 – 370
Hardox HiTuf is a type of Hardox steel having high wear resistance and toughness. Cutting edges and demolition can be made out of HiTuf Hardox steels.
Hardox Extreme
- Thickness of plate 10
- Brinell Hardness: 700
- Thickness of plate 25
- Brinell Hardness: 650
Hardox Extreme is the type of Hardox with the highest hardness values. This is why it is named “Extreme”. It is designed to meet the demands where extremely high resistance against wear products are needed. Cutting equipment, crushing machines, crushing hammers, and wear plates are some of the usage examples of Hardox Extreme steels.
