Dear Fauzan Huzaifah

Based on a consideration of the strain, stress, and temperature states associated with the formation of a white layer in machining, the S. Akcan et.al, in their article "Formation of white layers in steels by machining and their characteristics" concluded that the formation of white layer is promoted by:

The conditions of moderate to high cutting speed in conjunction with tool flank wear.

Deformation of material to very large strains which is the principal factor contributing to the formation of these layers with ultrafine grained or nanocrystalline structures.

The large strain deformation and elevated temperatures prevailing in the machining zone could also trigger dynamic recrystallization or cause decomposition and partial dissolution of the cementite present in the steels.

Now, all above promoting, principal and triggering factors could prevail during machining of hard steels and so producing white layers but not with the low alloy steel machining.

Best regards

Article Formation of white layers in steels by machining and their c...

Dear Mohammed Hussein,

Your answer helped me strengthen my insight.

Thank you