About Heat Treatment
Like any other process, heat treatment also has its limitations and issues. Whilst some relate to the process itself, a majority relate to external factors which are outside the control of a heat treater. Heat treatment involves heating parts to high temperatures followed by quick cooling. There are volumetric changes during the process, which are outside of the heat treater’s control. Other limitations or issues can range to a whole lot of variables ranging from material quality, section size, part geometry to prior
manufacturing processes which ae outside the control of heat treater. Accordingly, even though these problems or issues manifest themselves during heat treatment, we do not take responsibility for the failure and damage due to such issues, which may include distortion, cracking, low/ variable hardness etc during heat treatment or afterwards.
- Limitations: Limitations are generally related to material and shape / size of part. Achievement of heat treat specs depends highly upon the material used i.e. whether mild steel, constructional steel, alloy case hardening steel etc. It is not possible to achieve high core strength with mild steel. Similarly, high surface hardness cannot be achieved by carburising mild steels. Very large components may have limitations to the way they may be positioned and supported in containers for processing in furnaces. Large sizes may also lead to increased distortion or difficulty in achieving required results.
- Problems: The heat treatment process is highly dependent upon chemical composition and quality of material used for manufacturing component. This includes steel manufacturing practices or subsequent forming and manufacturing methods. Small changes in alloy compositions, which may still be within alloy chemical composition specification range, can lead to significant differences in final hardness despite correct heat treatment. Similarly defects like porosity, segregation, blow holes, non metallic inclusions, seams etc can manifest as distortion, cracking or hardness related issues. As these can be localised to an area only, metallurgical analysis may not be able to determine the root cause of a failure. Part geometry like section size changes, sharp corners, holes, keyways can lead to issues like distortion and cracking of parts during heat treatment.