All About Austenitizing on New Website - KnifeSteelNerds.com

[Larrin]

Ok, let me see if I understand it correctly (assuming scenario 1). Because grain boundaries are high energy areas for grain nucleation, when grains grow so large that they have consumed a vast amount of surrounding grains there are eventually so few boundaries left from which to grow new grains that production of new grains falls off rapidly.

In the grain growth regime the steel is not creating new grains but consuming smaller ones. You are correct that they boundaries are high energy areas that the steel wants to eliminate. That makes them preferential for nucleation. But during grain growth the boundary area is reduced simply through consuming smaller grains. The more growth that occurs the less boundary area there is and therefore the driving force for growth is lessened. So I am speculating that perhaps the grain size is large enough that the driving force has become low enough that further growth is slowed.

 

[i4Marc]

Ok, great. Thank you.