03-18-2019, 02:44 PM
I have read an interesting paragraph about carbide tearout in a review by Cliff Stamp:
Carbide tearout during sharpening in detail
As a point of clarification, carbides can be cut by a suitable abrasive, i.e., one which is harder than the carbides so it is not immediately obvious that a lot of carbide would so limit the ability to polish the edge. However as the abrasive cuts through the carbide there is an action/reaction force pair between the carbide and abrasive generated which in turn generates an action/reaction force pair between the carbide and the surrounding steel matrix, i.e., the non-carbide portion of the steel. As the edge angle of the cutting tool is reduced the carbides will be contained by less matrix volume and at some point there will no longer be enough matrix to sustain the action/reaction force pair and the carbides will get torn out of the cutting edge. Thus a steel with a higher carbide volume and larger carbide size requires a greater volume of steel matrix around the carbide to form a highly polished edge and keep that edge stable. A higher matrix volume around the carbides requires a greater angle as shown by Landes, Johnston and Elliot. As the abrasive is both harder and sharper there will also be less of an action/reaction force pair so the greatest edge stability will be found by using the hardest and sharpest abrasive as noted by Elliott.
Carbide tearout during sharpening in detail
As a point of clarification, carbides can be cut by a suitable abrasive, i.e., one which is harder than the carbides so it is not immediately obvious that a lot of carbide would so limit the ability to polish the edge. However as the abrasive cuts through the carbide there is an action/reaction force pair between the carbide and abrasive generated which in turn generates an action/reaction force pair between the carbide and the surrounding steel matrix, i.e., the non-carbide portion of the steel. As the edge angle of the cutting tool is reduced the carbides will be contained by less matrix volume and at some point there will no longer be enough matrix to sustain the action/reaction force pair and the carbides will get torn out of the cutting edge. Thus a steel with a higher carbide volume and larger carbide size requires a greater volume of steel matrix around the carbide to form a highly polished edge and keep that edge stable. A higher matrix volume around the carbides requires a greater angle as shown by Landes, Johnston and Elliot. As the abrasive is both harder and sharper there will also be less of an action/reaction force pair so the greatest edge stability will be found by using the hardest and sharpest abrasive as noted by Elliott.