Your objectives:

• Construction equipment and commercial vehicles that back up your brand promise, including visually
• Long asset life under the toughest conditions
• High efficiency and sustainability

Our solution:

Tata Steel's Valast AR steel for...

... long-lasting and consistent quality, even under the toughest conditions
... uniformly flat surfaces that are ideal for printing and painting, without the 'orange peel' effect
... high-quality surface finish that remains even after lengthy periods of usage
... time and resource savings, as less surface treatment is required due to a lighter scaling layer
... greater efficiency and sustainability thanks to availability in custom dimensions.

The details:

What do powerful commercial vehicles and construction equipment have in common with exotic sports cars? Both are technically advanced, deliver exceptionally high performance, are often worth more than €100,000 and look impressive. After all, the exterior should show what they are made of. Obviously sports cars are not used at construction sites, quarries or in recycling, but excavators, dump trucks or crushers should accurately represent the company they are used for over the long term and even in spite of challenges conditions. After all, it's also about the brand.

As is becoming clear, AR steels ensure an impressive appearance even under the toughest conditions. They are extremely resistant and have a high yield strength. With a guaranteed Brinell hardness value (HBW) of between 420 and 480, they are ideal for use in heavy vehicles and components such as tipper linings, excavator shovels or crushing equipment. However, not all AR steels are the same.

Great appearance over the long term even under the toughest conditions

Improved scale

Our Valast 400/450 - with a Brinell value of 400/450 - offers a better surface quality even compared to the market-leading AR steel manufacturers. This is mainly due to its scale layer. In any steelmaking process, an oxide layer (also called a scaling layer or scale layer) forms on the surface of the steel. AR steel is usually produced in a reversing plate mill and then cooled and hardened with water and/or air. This process results in considerable scale formation, which is usually uneven. In contrast, Valast is produced in a hot strip mill, which replaces the quenching method of the reversing mill process with a simpler cooling method. This results in a thinner and more homogeneous scale layer.

World-class surface quality

But what does this mean for the surface quality of the steel? Valast's lighter scale layer means that less shot blasting is required. The fact that the steel is more homogeneous leads to a more predictable result once the oxide layer is removed. After shot blasting a typical AR steel plate, you will notice that the surface has many imperfections, which can even be felt. This is because the scale layer on the sheet peels off in larger fragments. You can achieve a good surface without Valast, but it is significantly more time-consuming and the result will not be as long lasting. Firstly, any dents or imperfections need to be repaired with a filler and sanded down to get a smooth surface. Next, the surface needs to be primed and coated, which often produces a so-called "orange peel effect", which in turn is a result of the removed scale layer. This makes it necessary to sand the lacquer layer and reapply it until the surface is smooth and shiny.

This process not only wastes time, but also affects the longevity of your product. Once in use, the surface will be subjected to incredible forces and impacts, which - despite the use of AR steel - can lead to wear and abrasion. The main reason for this is the filler, which will peel off the steel surface in no time, causes the paint to flake off and the steel to rust. The sheet metal then looks old, worn and tired in no time.

But it doesn't have to be like this. Because of Valast's more homogeneous scaling layer, the resulting surface quality is significantly better. There is less need for shot blasting and no need for filling. There is also a reduced orange peel effect when painting, so you need to use less coating. All this leads to a shorter processing time, which in turn makes the production process more efficient. And since no fillers are needed, the surface stays more attractive for longer.

An AR steel that offers numerous benefits: Tata Steel's Valast:

Valast 400/450 wear-resistant steel has been developed based on decades of steel expertise and extensive application knowledge. It has been specially developed for use in construction, mining and agriculture. The dependable wear-resistant strip steel grade with the widest dimensions available on the market brings numerous benefits for your processing - with opportunities to increase yield and reduce waste. Thoroughly tested, fully accredited and only available through a proven supply chain, Tata Steel's Valast not only gives you a more attractive product in the long run, but also adds value.

Our challenges:

• Successfully implementing a new manufacturing process for Valast
• Ensuring consistent product quality

Our solutions:

• STORM: our in-house software to optimise the cooling process
• Achieve tight tolerances and optimum surface quality

The details:

The development of every steel product presents our engineering team with new challenges. Whether it's updating a paint colour, the chemical composition of the steel or introducing a completely new product like Valast 400/450: Most of the time, it is necessary to make changes in the manufacturing process. To be able to produce Valast with the tight tolerances and exceptional hardness and surface quality we wanted, we had to thoroughly rethink the heating and cooling process. 

When steel is processed in a hot strip mill, it is fed into the rolling mill as a slab at a temperature of around 1200°C. The steel is then cooled in five pre-rolling mills. After the steel has been rolled to the correct size in five roughing stands and seven finishing stands, it is cooled with water jets positioned above and below the steel strip. The challenge is that the cooling rate needs to be particularly high in order to achieve the optimum product properties, cooling the steel as quickly as possible. However, the existing cooling system was not capable of doing this - after all, it was installed long before the idea for Valast 450 was even conceived. The most obvious solution would have been to upgrade the existing cooling system. However, this would have taken a lot of time and led to unwanted downtime for our hot strip mill, which was in continuous operation. We had to find another option.

Our development team includes highly qualified specialists in process control and process engineering. They are able to design and replicate processes on a virtual model of the hot strip mill. We confronted them with our challenge, and what they found was surprisingly simple: they realised that the hardware already in place was perfectly capable of passing enough water through the jets to cool the steel sufficiently. The limitation was in the software used to control the process so far.

After talking at length with suppliers of this type of control software, we realised that they could not help us. So we turned back to our own R&D team. They finally succeeded in developing a customised software programme for the process control of the run-out system (or Run Out Table; ROT for short): Tata Steel's STORM programme. The abbreviation stands for the somewhat unwieldy "Smart Temperature Optimisation on the Run Out Table for Mechanical properties control", but the solution behind it has an immediate effect. STORM enables flexible temperature control between upper and lower cooling to achieve the desired microstructure of the steel. The cooling bars on the ROT are designed so that the upper section removes the same amount of heat as the lower section. This was achieved by increasing the flow rate of the lower level cooling by about 20 % compared to the upper section. Due to the improved process control, the steel was cooled sufficiently and with the level of control we needed, thus achieving the tight tolerances and surface quality of Valast 400/450 that our customers expect.
 

An AR steel that offers many benefits: Tata Steel's Valast:

Valast wear-resistant steel has been developed based on decades of steel expertise and extensive application knowledge. It has been specially developed for use in construction, mining and agriculture. The dependable wear-resistant strip steel grade with the widest dimensions available on the market brings numerous benefits for your processing - with opportunities to increase yield and reduce waste. Thoroughly tested, fully accredited and only available through a proven supply chain, Tata Steel's Valast 400/450 not only gives you a more attractive product in the long run, but also adds value.

The challenges:

• High AR product quality for the toughest operating conditions
• High design flexibility
• Optimum price-performance ratio

The solutions:

• Our wear-resistant Valast 400/450 strip steel for optimum product consistency and surface quality
• Customised lengths and the widest dimensions available on the market for minimum waste
• New decoiling and packing line for optimum availability

The details:

As with many other steel grades, there are two different manufacturing processes for wear-resistant, so-called "abrasion resistant" or AR steels: one is AR hot-rolled strip, the other is AR reversing mill plate. What are the fundamental differences and, above all, how do they affect important product properties such as surface quality, durability or design flexibility? Does it make sense to use sheet or plate for applications in the most challenging conditions?

The rolling process makes a crucial difference: Tata Steel's Valast 400/450 is a wear-resistant hot-rolled strip product specifically suited for use in construction, mining and agriculture and is manufactured in our state-of-the-art hot strip mill in IJmuiden, the Netherlands. Our main competitors offer AR steel with similar Brinell hardness grades, but usually as reversing mill plate.

The hot strip mill where Valast is produced is more than 800 m long. A steel slab is heated to 1250°C, descaled and then enters the first of five roughing stands. Here the steel slab becomes an intermediate slab, which is about 70 m long and 40 mm thick. This is descaled again. It then passes through a seven-stand finishing mill, which rolls the strip further until it reaches a thickness of between 2 and 12 mm - depending on the customer's requirements - and a length of between 200 and 1200 metres. After passing through the finishing line, it is cooled down from about 900°C to less than 250°C and wound into a coil. This can then be decoiled and cut to the desired length as required.

Heavy plate, on the other hand, is produced in a reversing plate mill, which is usually only about 60 m long. The steel slab (or supplied plate) goes into a simple reversing mill and is rolled back and forth until it reaches the desired thickness. From this point, the plate is repeatedly heated and then cooled with water (quenched) and air (hardened). The result is steel plates with fixed dimensions. 
The different production methods for AR hot-rolled strip and reversing mill plate result in very different qualities of the finished steel. The following overview compares the different quality characteristics.

The differences between AR hot-rolled strip and AR reversing mill plate in detail

Surface quality

During plate production, the additional heating required for the quenching and tempering process can lead to considerable oxidation, known as a scale layer. When this is removed by abrasive blasting, it can cause dents and scratches on the surface that need to be repaired, affecting both the use and the life of the final product. In contrast, the one-off reheating in steel strip production, combined with efficient descaling and direct quenching after hot rolling, results in a thinner layer of scale that is easier to remove. This improves the quality of the surface, which requires less treatment and lasts much longer.

Product consistency and thickness tolerance

In reversing mill plate production, each plate is rolled individually. When the material is fed to the rolling gap, a certain amount of stabilisation must take place. This can cause the thickness at the edges of the plate to deviate slightly from that in the centre. Therefore, the thickness tolerance, flatness and overall product consistency may vary throughout the sheet production, causing each sheet to have differences.

As a single Valast 400/450 strip can be up to 1200 m long, it is not affected by unevenness in the same way. While there is always some variation on the first and last metres of the strip, these sections can be removed when the steel is decoiled. Tata Steel also uses a total of 12 rolling stands in the hot strip mill, which provide additional product homogeneity. At the end of the process, more than 95% of the Valast strip has a consistently uniform quality.

The fact that a Valast coil is produced from a single slab also guarantees a consistent chemical composition over the entire length of the product. Thus, a full truckload of Valast 400/450 can come from a single coil with the same production parameters. This means that the steel from this delivery can be used to produce any sheet with identical production parameters. This allows us to achieve maximum homogeneity, and processing for the customer becomes easier and, above all, more efficient.

Length, thickness and width according to customer requirements

The maximum length of a heavy plate is usually 12 m. To maximise efficiency, steel plate manufacturers supply the product in a range of standard sizes. Conversely, this means that customers often have to order more material than they need and have a relatively large amount of waste when processing the steel further. In this case, too, hot-rolled strip is a more efficient solution. Due to the length of the steel strip, there are practically no limitations and the Valast coils can be cut entirely to the customer's individual requirements. This helps to reduce waste, allows customers to optimise space requirements, reduces overall costs and protects the environment.

When it comes to thicknesses and widths, sheet steel usually has an advantage over hot-rolled strip. For example, plate can be offered in greater thicknesses because it does not have to be coiled as hot-rolled strip does. However, Valast is available in thicknesses of up to 12mm and is therefore suitable for almost all applications. Hot-rolled strip is usually also offered in narrower widths than plate. But here too, Valast offers greater possibilities than standard hot-rolled strip. In fact, our AR steel is available in widths up to 2.0 m, offering users greater design flexibility.

New decoiling line under development

The last important step in ensuring optimum product quality of AR steel is decoiling, i.e. decoiling the steel strip for further processing. This process is undertaken by a decoiling line. It processes steel coils into sheets. At the Maastricht Service Centre in Feijen, part of Tata Steel, preparations have begun for the installation of a new, state-of-the-art decoiling line and an automated packing line. With the commissioning of the new facility, production will be faster and more accurate. The commissioning of the new plant is expected to be given in 2023.

An AR steel that offers many benefits: Tata Steel's Valast:

Valast 400/450 wear-resistant steel has been developed based on decades of steel expertise and extensive application knowledge. It has been specially developed for use in construction, mining and agriculture. The dependable wear-resistant strip steel grade with the widest dimensions available on the market brings numerous benefits for your processing - with opportunities to increase yield and reduce waste. Thoroughly tested, fully accredited and only available through a proven supply chain, Tata Steel's Valast not only gives you a more attractive product in the long run, but also adds value.

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