Use of medium frequency induction heating pipe bending machine

In actual metallic materials, grain boundaries or intragranular areas contain numerous fine, refractory precipitates of austenite phase. When grain boundaries encounter these precipitates during their migration, they bend, increasing the grain boundary area and energy, thus hindering grain boundary movement and acting as grain boundary pinning agents. Therefore, the presence of austenite phase particles is a resistance to grain boundary movement. When the volume percentage of precipitates is constant, the finer the particles and the higher their dispersion, the greater the resistance to grain boundary movement.

In the presence of austenite phase particles, the austenite growth process is hindered by these dispersed precipitates. As austenite grain growth continues, the total grain boundary area gradually decreases, and the grain growth driving force gradually decreases. When the grain growth driving force and the resistance of the dispersed precipitates reach equilibrium, austenite grain growth ceases.

(This is from a training manual for heat treatment technicians.) In summary, austenite grain growth in medium-frequency induction heating pipe bending machines is a spontaneous process, primarily manifested as grain boundary displacement. Highly dispersed refractory phase particles significantly inhibit grain growth. To obtain fine austenite grains, it is essential to ensure that the steel contains a sufficient number and fineness of refractory phase particles.