Heat treatment of metal, we optimize the coating

The most important processes at InProCoat

The heat treatment of steel can change material properties such as surface hardness, strength, temperature resistance and ductility, thereby significantly extending the service life of metallic components. We use these processes, among others, for this purpose:

Quenching and tempering - improves the toughness of your steel
Annealing (solution annealing, normalizing, stress relief annealing) - Influences the material properties depending on the purpose

We would like to introduce you to the individual heat treatment processes in more detail below.

Would you like heat treatment for your project? Contact us directly!

Why is heat treatment important in connection with pipe coatings?

Heat treatment is a crucial step in pipe coating as it improves the adhesion and durability of the coating. It helps to create a strong bond between the surface of the pipe and the applied coating.

What types of pipe coatings require heat treatment?

Many types of pipe coatings require heat treatment, especially polymer-based coatings such as epoxy or polyurethane coatings. These coatings often need to be cured at certain temperatures to be fully effective.

How is heat treatment carried out during pipe coating?

Heat treatment is normally carried out after the coating has been applied. The pipes to be coated are heated to the specified temperature in an oven or heating system. The temperature and duration of the treatment vary depending on the type of coating and the requirements of the project.

How do you choose the right heat treatment for your pipe coating?

Choosing the right heat treatment depends on several factors, including the type of coating, the materials of the pipe and the requirements of the project. It is advisable to work closely with experienced pipe coating professionals to determine the optimum treatment. We would be happy to provide you with individual advice on heat treatments for pipe coatings.

Quenching and tempering steel

The tempering of steel is a combination of hardening and tempering, whereby the tempering temperature is usually above 550 °C. This form of heat treatment is used to significantly improve the toughness properties at a given tensile strength. The highest toughness is achieved by tempering a purely martensitic hardening structure.

Tempering is only suitable for hardenable materials. In addition to steel, this also includes non-ferrous metals such as titanium alloys. The hardenability of the material depends on whether it is able to form a martensite or bainite structure. In addition, the hardenability depends on the grain size of the microstructure, which influences the temperature-dependent transformation processes.

For classic tempering of steel, it must have a carbon content of 0.2 to 0.3 percent. For steels with other properties, so-called surface hardening is recommended.

Annealing

Annealing refers to the heating, soaking and subsequent cooling of workpieces to achieve special material properties.

The heating phase serves to bring the steel to the holding temperature. During the subsequent holding phase, the temperature in the workpiece is equalized and the physical and chemical processes in the material are brought into equilibrium. In the final cooling phase, the temperature of the steel is lowered back to ambient temperature.

Different processes are used for this type of heat treatment depending on the desired goal.

How does normal annealing work?

One of the most important heat treatment processes is normalizing, which gives the steel a uniform, fine-grained structure with homogeneous properties. This method is used in particular for carbon steels or low-alloy steel grades in order to normalize their structure after hot rolling or casting. The hardness that can be achieved with normalizing depends on the properties of the steel and the cooling rate. In principle, hardnesses of 100 to 250 HB can be achieved.

During the annealing process, the steel is heated to a temperature that roughly corresponds to its hardening temperature. This causes new austenite grains to grow, which are significantly smaller than the original ferrite grains. New, finer ferrite grains are then formed during cooling.

How does solution annealing work?

During the hot forming of steel workpieces, structural transformations occur as a result of the influence of heat and uncontrolled cooling. This mainly affects austenitic steels, where high temperatures in the range of 500 to 800 °C can cause carbide precipitation at the grain boundaries. These precipitations lead to intercrystalline corrosion due to deviating electrochemical properties and must therefore be processed and dissolved again by annealing.

Solution annealing, also known as diffusion annealing, is carried out at relatively high temperatures of 1050 to 1300 °C. The process takes up to two days and ensures the uniform arrangement of foreign atoms in the metal lattice. The formation of the phases and therefore also the properties of the steel are determined by the choice of cooling rate.

How does stress-relief annealing work?

Stress relief annealing is mainly carried out on steel in a temperature range of 480 to 680 °C, whereby the holding time can be one to two hours. This heat treatment process largely eliminates residual stresses in the workpiece that were previously caused by machining or mechanical deformation. This reduces unwanted distortion during the final mechanical finishing process. Stainless steel with niobium and tantalum content is not suitable for stress-relief heat treatment.

How does soft annealing work?

If resistance to high mechanical forces is less important for a steel workpiece, but good formability and machinability are all the more important, soft annealing is the optimum heat treatment process. In order to reduce hardness and strength, soft annealing at temperatures of 650 to 750 °C reduces existing cementite or pearlite precipitates.

Heat treatment with InProCoat

Our company has a new high-performance, extremely precise bogie hearth furnace in which we can carry out various heat treatment methods at temperatures from 200 to 1050 °C. Regular TÜV monitoring ensures that all processes are carried out correctly and that optimum results are achieved.

We can process parts with an individual weight of 25 tons to any specification. We fulfill all requirements according to AD-Merkblatt HP 7/1-3.

With our many years of experience and in-depth expertise, we will be happy to help you find the right heat treatment process for your project. Get in touch with us and let us advise you individually!