S30V vs S90V

[Vishnu]

I want to make the best kitchen knife possible, and I'm lookin at the CPM's because of all the good things people have said.... But when I look at pages telling the properties of various steels, they tend to talk about toughness and wear resistance. How are these measured? WHat could I expect if I was to use the S90V vs S30V? Is the numerical name at all related to the quality (ie: 30 is better than the 90)?? And are the numbers at all relative when dealing with the carbon steels also?

Any help makin sense of the graphs about toughness and wear resistance would be greatly appreciated!!!

Thanks guys, ahead of time!

[Jerry Hossom]

Generally speaking, making sense of it isn't easy. S90V contains 9% Vanadium. S30V contains 4% Vanadium (originally it was planned for 3% and thus the name). Vanadium carbides are VERY hard and provide a lot of wear resistance. On the flip side of that S30V was designed to be very tough; it resists chipping and breaking. S90V was designed to be very wear resistant, so it's really a tradeoff. If you're very careful with your knives, don't toss them in the sink or hammer them through hard beef bones, S90V will do very well. If you're rough on a knife, S30V will be a better choice. I'd likely choose S30V for larger knives, because they're subjected to greater stresses. S90V is certainly fine for smaller knives.

As for carbon steels, the numbers are sometimes relevant, sometimes not. In the 10xx series, it relates to the percentage of carbon. 1095 has 0.95% carbon, 1060 has 0.6% carbon, etc. In steels like O1, M2, W1, etc. I don't think the numbers don't mean much.

[R. Lemmen]

I know that Jerry already knows this and probably didn't want to spend a half an hour talking about it but I bite my lip every time I hear a half finished description:

According to the venerable Machinery's Handbook, AISI (American Iron and Steel Institute) / SAE (Society of Automotive Engineers) Tool Steel Descriptions:
Water hardening tool steels (chisels, forging tools, punches):
W = Water hardening
Steels for cold work (general purpose):
A = Air hardening, medium alloy
O = Oil hardening
D = High carbon, high chromium
High speed steels (mainly for metal cutting tools):
M = Molybdenum
T = Tungsten
Shock resistant tool steels (punching and forging applications):
S = Shock resistant
Special purpose tool steels (high toughness applications where abrasion resistance is not important):
L = Low alloy
The number suffix relates to their chemical classification as decided on by the AISI and SAE in collaboration with industry. The number does not directly relate to quantity of main alloying elements as with the AISI 1xxx/4xxx/5xxx steels. It's important to note that there is a lot of crossover in usage between the catagories of steel. D2 and S7 seem to get used almost interchangeably in some of the industrial punching and forging operations I've seen.

[Jerry Hossom]

It's much easier to provoke someone else to do it than to type in all that stuff...