Steel often undergoes heat treatment through thermal, industrial, and metalworking procedures which change the chemical and physical properties of the material. Heat treatment makes High speed steel, one of the most popularly used steels more resistant to high temperatures. The steel retains its original quality and does not melt easily when exposed to higher temperatures. There are certain steps in heat treatment that make the steel robust and tough. Few of the features get added when the steel goes through a heat treatment procedure. Annealing, hardening, normalizing, tempering are the steps.
Think about the application – Clients often make the mistake of buying heat treated steel only to use it for hot forging and other industrial applications involving heat. This will only lead to a waste of money and the client would be paying for heat treatment costs in vain. One should only opt for heat treated steel when the purpose of the application is direct machining. Clients also often buy high speed steel or cold work steel because these are the most commonly bought in the market. However, the focus should be to buy the steel suitable for the task at hand. Another misconception among clients is to opt for steel that has been hardened. In that regard, one should know that while hardening makes steel stronger and ductile, it also makes it more brittle. Thus, additional tempering must be done in order to ensure the steel doesn’t break during heavy machining.
Heat treatment is not the ultimate yardstick for measuring the strength of steel – Undoubtedly, heat treatment renders steel with a certain degree of robustness, toughness, and sometimes hot hardness. However, that are not the final features to measure the strength of any steel. Other mechanical properties such as ductility, malleability, and others should also be taken into consideration. For instance, in the case of high speed steel Rockwell hardness is one of the determining characteristics.
Uniformity of heat treatment and overall product – The steel would be used as a whole during application. Therefore, focusing simply on the edge of long solid bars or the center of a sheet of steel is not ideal. Uniformity must be the key approach for choosing a heat treated steel. If the whole block of steel is good enough for the application, then only it should be chosen for the selected task.
Is heat treatment suitable for the particular steel – Sometimes after the heat treatment of steel, the hardness required for it decreases compared to its raw form. In other cases, the hardness hardly varies between the heat treated steel and the raw material steel. For such cases, wasting capital on heat treatment is unnecessary because the final product does not add to its earlier features. For steel that would be directly machined, one important factor of knowledge should be – at which stage the product’s mechanical and physical properties are to be tested. Clients often misjudge situations like these. In certain industrial applications, it is better to opt for heat treatment than pre machining. Understanding the type of steel, its grade, and its application is the key to choosing the steel.
Steps integral in heat treatment – While hardening is important for steel, what is more, important is to ensure the drawbacks added to the steel during hardening are removed. For instance, tempering is one of the necessary steps to follow when steel is heated at a temperature below its hardening point. The steel is kept at that temperature for a long time. After that, the steel is allowed to cool to normal air temperature. During annealing, the microstructure of the material is altered in order to change its mechanical or electrical properties. Annealing is performed on steel to ensure that the hardness is reduced, and ductility is increased to make it more functional. Of course, the hardness would be required for steel when it is finally used. That is why the latter steps such as hardening are important. It ensures that the steel is overall good for its use.