10-28-2018, 11:27 AM
Mr. Grepper, steel annealing is relatively slow diffusion process increasing ductility and decreasing hardness. In my understanding, during grinding, annealing does not occur, because the duration of the heating is too short. The fact that at some spots the temperature may be very high is not sufficient for annealing.
Steel of the blade after standard heat treating is in a metastable state, which is not stable and the desire of the steel is to move from this transient state towards a phase with lower inner energy. To accomplish this the steel needs some additional heat energy.
In my thinking the limited heat energy generated during grinding can cause some re-arrangement of iron atoms which form the martensite microstructure. Based on prof. Verhoeven the martensite was formed in milliseconds during quenching. It is easy to imagine that some iron atoms forming this martensite can adjusts their positions (occupied in a hurry) and so lower the inner energy. IMHO this quick atomic re-arrangement will cause some loss of blade hardness.
Jan
Steel of the blade after standard heat treating is in a metastable state, which is not stable and the desire of the steel is to move from this transient state towards a phase with lower inner energy. To accomplish this the steel needs some additional heat energy.
In my thinking the limited heat energy generated during grinding can cause some re-arrangement of iron atoms which form the martensite microstructure. Based on prof. Verhoeven the martensite was formed in milliseconds during quenching. It is easy to imagine that some iron atoms forming this martensite can adjusts their positions (occupied in a hurry) and so lower the inner energy. IMHO this quick atomic re-arrangement will cause some loss of blade hardness.
Jan