Heat treatment

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Heat treatment is a scientific process that can change the properties of a material, by heating it to a specific temperature. The process of heating steels or metals is not aimed to reach its melting stage. Heat treatment process is mainly aimed to reach a proper temperature for working processes like forging , hot forming and hot deep-drawing, but it can also be aimed for a partial process like solution annealing, normalising, tempering, stress relieving, soft annealing and many more. Solution annealing very often is followed by quenching/ cooling at a dedicated temperature. These heat treatments can be applicable after cold working the material. Air cooling, enforced air cooling or quenching is cooling the metal in a specific way to reach the desired mechanical properties. Depending on the selected temperature and cooling speed during this process and the duration of the complete treatment, a material can be made softer, stronger, harder or tougher.

 

One of the most common uses of heat treatment, is making the metal softer. So it is easier to form. It also can make metal stronger and more resistant to various aspects that can affect resilience.

Quenching + Tempering and Quenching can lead to Residual Stresses

Quenching of Carbon Steels followed by tempering is what we call a QT quality of steel. This heat treatment is performed to create higher mechanical properties into the steel. If these steels cool down in still air, the strength is lower since the material reaches phases which are not as strong, the longer the material is cooling down in air.

Quenching of Stainless Steels is perform in order to keep the steels in the metallurgical phases of the material and freeze these phases in this stage.

Quenching makes sure that preferable phases are maintained in the steels. Quenching however generates residual stresses in the steel. This can easily be explained by us. Visualizing these stresses is also possible.
Residual stresses in Carbon Steels can be reduced by tempering. But they also can be increased by the same process if the time of tempering or the tempering temperature are not correctly chosen.
These residual stresses sometimes can lead to cracking of the product after quenching. This is a known phenomena in the forging industry.
These residual stresses can lead to leaking of flange-connections or seal connections after pressure testing or after time in use.
It is a complex but very interesting process. We will be happy to explain the phenomena to you. With modern simulations software this phenomena can be visualized.

Measuring Temperature

Measuring product temperature seems simple but it only is simple if you know how to do it properly. Calibration of your furnace temperature is essential for your process. The way you measure the product temperature can save you time and money. Measuring product temperature during cooling and/ or quenching can give you essential data. If they represent the product temperature, you can only discover by measuring both. Most of the time you will only get or generate the furnace temperate curves. Strange enough almost nobody is asking for the cooling/ quenching curve. The moment you have trained how to measure the product temperature, not only study the temperature, but also the speed of heating up and/or cooling down, you will be surprised about what you can recognize and learn about metallurgical phases.

Temperature control during heat treatment is essential

Measuring the temperature is also important during welding. Also welding is a heat treatment.

 

Interested? Feel free to join our masterclasses, trainings, or workshops or ask for trainings on this subject.

Heat treatment trainings and masterclasses

Heat treatment has a lot of beneficial advantages. That is mainly the reason why we like to offer support to our customers, in the form of (inhouse-) trainings courses and masterclasses. In this way we share our knowledge about the treatment process and its benefits. Our goal is to ensure that our customers have a sustainable future.