How is Quenched and Tempered Steel Made and What are its’ Applications?

Steel manufacturing processes have changed radically over the past fifty years. We now can fabricate cleaner, leaner, stronger and more durable steel than ever before.

 

Previously weldability and ductility would come at the expense of the material’s toughness and sturdiness. That was, however, until the quenching and tempering came around. Quenched and tempered steel is both highly abrasion resistant, very strong and has several enhanced properties due to the way it is fabricated.

 

In the following article we are going to outline how quenched and tempered steel is produced, what properties quenched and tempered steel has, and the applications it has in modern industry.

 

What does the quenching and tempering process involve?

 

The quenching and tempering process is able to strengthen materials, such as steel and iron-based alloys, to make them extremely tough. The process of quenching is also known as quench hardening. This process involves the heating of materials to extreme temperature, followed by cooling via water, air, oil o using inert gases such as nitrogen.

 

The whole quenching and tempering process is tightly monitored. Every stage of the process must be done with precision. The process involves keeping a close eye on the heating temperature, the cooling methods used, the types of substances used to cool, and the time taken to allow the steel to cool. This process goes on as long as necessary in order to achieve the desired hardness of the product.

 

Right after the quenching, the material will be at it’s hardest state. The next step of the process is known as tempering. The tempering process involves achieving greater ductility and toughness by decreasing hardness.

 

The tempering process involves heating the quenched material to just below the critical point for a period of time, then allowing it to cool for whatever period of time whilst still in the air. It is important that the temperature and the heating time change depending on the composition of the material. Determining the right temperature and duration will give the fabricator the opportunity to optimise the material so that it meets the exact hardness requirements.

 

Why use Quenched & Tempered Plate Steel? What are some of the benefits of Quenched and Tempered Steel?

 

The quenching and tempering process has several benefits. The primary benefit of quenching and tempering steel is that is allows it be less brittle and increases ductility. However, what makes it exceptional is that is does all this without sacrificing much hardness, which would normally be completely lost through other typical steel processing methods. The combination of toughness, ductility, weldability, and hardness is what sets quenched and tempered steel plate above typical carbon based steel.

 

Toughness means that the material has a much greater resistance to wear and tear; it can also avoid abrasion easily. Quenched and tempered steel is very useful when using machinery and in scenarios where structure may come into frequent contact with tough materials. Abrasion resistance is a quality that is often sought out for construction, quarrying, earthmoving, and mining industry equipment.

 

What are some common applications of quenched and tempered steel plate?

 

Quenched and tempered steel plate may come in several different grades and thicknesses. It can be used for a variety of applications. The application depends on the grade and thickness of the steel. Some common grades include the following:

 

  • 80 grade steel. This type of steel is a high strength, low alloy structural steel used for a variety of construction and mining uses. Some of the applications of this type of steel include: storage tanks, bridges and high rise buildings, excavator, low load trailers and loader buckets.

 

  • 400 grade steel. This type of steel is a high hardness, abrasion resistant product. A few applications of this type of steel include deflector plates and gear wheels. 400 grade steel is also common in the production of earthmoving buckets and chutes.

 

  • 500 grade steel. This type of steel is a medium carbon, high hardness and highly abrasion resistant material. This grade is the toughest of the lot and can often be found in earthmoving buckets, dump truck wear liners and even chutes.

 

Are quenched and tempered steels readily able to be welded?

 

It is possible to weld quenched and tempered steel, however, great care must be taken to make sure that procedures are kept to at all times. It will depend on the quality of the quenched and tempered steel. Some steel may crack under pressure, however, some quenched and tempered steels have been developed with low carbon content and as a result, have excellent weldability qualities.

 

There are heat input limits set by manufacturers. It is also important to note that there can be problems with softening of the heat affected zones (HAZ) if the cooling rate of the weld is much slower than the quenching process has taken.

 

It should also be mentioned that increased thickness of quenched and tempered steel can also lead to increased susceptibility.

 

What are some of the latest technological advances in Quenched and Tempered steel plate?

 

There are many companies internationally doing excellent work in research and development to improve the processes used to achieve different grades of steel. One such company is BlueScope Plate Supplies, who have worked alongside Bisalloy steels to revolutionise the quenching and tempering process in terms of steel fabrication.

 

Since the early 1980s, these two companies have developed strong and abrasion resistant steels for Australia’s toughest industries. Bisalloy in particular has brought the quenching and tempering process into the 21st century.

 

Whereas traditional manufacturers would quench and temper steel focussing on performance and reliability in harsh environments (mining, construction and defence), Bisalloy has spent the last twenty years focusing on enhancing product flatness and surface improvement. This, combined with greater weldability and ductility, has made their products stand out in the industry.

 

As opposed to conventional T-1 steels, Bisalloy’s range of unique quenched and tempered steel offer fabricators, end users and designers greater flexibility.

 

Bisalloy and BlueScope Plate Supplies are taking quenched and tempered steel into the modern era through refinement of chemistries and processes. The result of the hard work is a low-carbon equivalent with greater weldability, impact toughness and formability. These modern quenched and tempered steel products have hardness up to 400HB at a thickness of less than 20 millimetres, and a carbon content level of less than 0.45. This allows the steel to not only be strong but highly weldable.

 

Bisalloy and BlueScope Plate Supplies’ Increased Flatness of Quenched and Tempered Steel Plate

 

Flatness is a key factor in delivering high quality quenched and tempered steel. Bisalloy have improved the flatness of their products by the addition of a cold plate leveller used during the production process. Flatter steel plate allows the edges of the material to be better aligned. This will result in less time needed to weld joins, cost-savings and will help facilitate the process of flame cutting, drilling and machining. Flatter steel plate is also more consistent when pressed or rolled. The appearance of the steel after fabrication and painting is greatly enhanced.

 

The addition of a cold plate leveller, is only a part of the $2.75 million upgrade conducted in 2000 to upgrade and improve performance. Standard processing procedures can be established, and new roll cassette change systems mean that levelling 5 millimetre and 25 millimetre can all be done on the same machine.

 

Bisalloy and BlueScope Plate Supplies’ Improved Surface Condition of Quenched and Tempered Steel Plate

 

The other important factor in developing high quality modern quenched and tempered steel is the surface condition of the steel. In the past, quenched and tempered steel will have heat treatment scale one the plate surface. This can be problematic, especially when it comes to flame cutting, welding or even bending.

 

The new million dollar on-line shot blasting facility introduced at Bisalloy has allowed them create steel with a far smoother surface. These innovations have helped eliminated the need for grit-blasting, preparation cleaning by fabricators, and grinding – the result is savings in time and money.

 

Although several gains have been made, there is still ongoing research and development being funded in order to better the quality of flatness and surface conditions of quenched and tempered steel plate.

 

Summary

 

Quenched and tempered steel plate is one of the most valuable types of steel available on the market. It can be used for a wide variety of applications – particularly by fabricators, designers and end users in the Construction, Mining and Transport industries. There are several grades of quenched and tempered steel available on the market.

 

It’s increased weldability, matched by it’s toughness, abrasion resistance and hardness, are what make it desirable for tough projects. Examples of it’s application may include the following: mining equipment, bridges, dump truck liners, earthmoving buckets, deflector later, transport equipment and lining equipment.

 

For more information about quenched and tempered steel, we recommend you follow up with a local supplier, manufacturer or fabricator to find what quenched and tempered steel product meets your needs.

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