Grain growth kinetics
Grain growth kinetics describes how the average grain size in a metal changes over time and temperature. This affects the mechanical properties of the material at high temperatures.
Physico-chemical mechanism of action
Grain growth kinetics is the process by which grain size in a metal changes over time and temperature. This happens to minimize grain boundary energy, which in turn reduces the total energy of the material.
Metallurgical relevance & risks in welding
Too fast grain growth can lead to a fine grain size, making the material softer and impairing its mechanical properties. Too slow growth can lead to a large grain size, which increases toughness but also reduces plastic deformability. Both extremes can lead to cracks or failure in the material.
Workshop practice & action instructions
To achieve optimal grain growth, the weld pool should be controlled so that temperature and time are optimal. A typical target is a mean grain size of 50 to 100 µm. This can be achieved by selecting the appropriate welding process (e.g., TIG welding) and the correct process parameters.