01-04-2015, 10:30 AM
I think the reason that the "magnetic" stainless steels such as 416, 420, 440F, 440C and other martensitic and ferritic stainless steels are so often used in knife making is because that carbon content adds the ability to be a little harder and maintain the sharp edge. An austenitic 300 series stainless (303, 316, 321, 347) just don't seem to have the hardness needed. Looking at the tensile and yield strength values for the 400 series versus the 300, it's no contest. The 400 series stuff is quite a bit stronger and can get much harder.
In ceramics, the hardness is always there, but so hard it's downright brittle. When I worked for Norton Company in their High Performance Ceramics Research & Development Center (Northborough MA) there was work going on to find new materials for knives. It's BIG business in meat packing here to have your knives in the plants, and they went after it with Transformation Toughened Zirconia. That ended up being the overall winner, beating many variations of silicon carbide, aluminum oxides and SiAlON. You could actually get a bit of a bend in the TTZ blades. The other materials had better properties under heat, but knives never see elevated temperatures.
I have no idea if they sold the ideas off to the big knife makers, got it stolen, or stole it themselves but it seems to be the material of choice to this day.
In ceramics, the hardness is always there, but so hard it's downright brittle. When I worked for Norton Company in their High Performance Ceramics Research & Development Center (Northborough MA) there was work going on to find new materials for knives. It's BIG business in meat packing here to have your knives in the plants, and they went after it with Transformation Toughened Zirconia. That ended up being the overall winner, beating many variations of silicon carbide, aluminum oxides and SiAlON. You could actually get a bit of a bend in the TTZ blades. The other materials had better properties under heat, but knives never see elevated temperatures.
I have no idea if they sold the ideas off to the big knife makers, got it stolen, or stole it themselves but it seems to be the material of choice to this day.