Advantages and Disadvantages of Different Post Weld Heat Treatment Techniques
Posted on 01-05-2023 03:37 PM
Post weld heat treatment techniques are used to improve the properties of welded components. They can help in strengthening, toughening, hardening or even restoring the ductility of a weldment. Each technique has its own advantages and disadvantages which must be taken into account when choosing one for a particular application.
Firstly, normalizing is a popular post weld heat treatment process which involves heating above the critical temperature and then cooling in air. It provides uniform grain size and improved mechanical properties. However, it requires precise thermal control and may not be suitable for some materials due to their sensitivity to thermal stress.
Additionally, tempering is another important technique where the material is heated at low temperatures below recrystallization temperature before cooling slowly in still air or oil. This process increases toughness by relieving internal stresses but decreases hardness as well as tensile strength of the component! Moreover, tempering may produce undesired changes in microstructure if not properly controlled during cooling phase.
Furthermore, austempering is a process that involves quenching from austenitizing temperature to a temperature below Ms (martensite start) followed by holding at this temperature for certain period of time known as soak time and then cooled again in still air or water bath. It results in increased ductility and toughness along with improved fatigue life; however it may lead to dimensional changes if carried out improperly.
Lastly, martempering is similar to austempering except that it involves quenching from high temperatures directly into a molten salt bath instead of air or oil bath leading to rapid cooling rate needed for martensitic transformation without excessive distortion caused due to thermal shock! On top of that, martempering also produces more uniform microstructure compared to other processes but tends to increase brittleness due to increased hardness associated with martensitic structure formed after transformation.
To conclude, each post weld heat treatment technique has its own set of pros and cons which must be considered while selecting an appropriate method for particular application so as to ensure maximum benefit with minimum cost incurred!