Thread: Stainless blades

Originally Posted by onimaru55

Just a technicality but stainless razors are 'tougher' rather than 'harder'. They would usually be tempered like a 'softer' carbon steel razor. SS is abrasion resistant tho so can take a little bit more honing.

That's what I heard - that they take extra effort to hone. I have enough trouble as it is with carbon razors....!!

Originally Posted by rum

That's what I heard - that they take extra effort to hone. I have enough trouble as it is with carbon razors....!!

Excuse me for sweating the details, but it is the HARDNESS of stainless that makes it both more scratch resistant and more difficult to hone.

TOUGHNESS is related to flexibility (ability to return to its original state after being bent or torqued).

Originally Posted by Gammaray

Excuse me for sweating the details, but it is the HARDNESS of stainless that makes it both more scratch resistant and more difficult to hone.

If you like details. Vintage Friodurs are made of 440 C which is not functionally harder than most carbon steel.
If you're talking about newer exotic SS then it may be on par with carbon for a high Rockwell level but not harder.

Originally Posted by Gammaray

Excuse me for sweating the details, but it is the HARDNESS of stainless that makes it both more scratch resistant and more difficult to hone.

TOUGHNESS is related to flexibility (ability to return to its original state after being bent or torqued).

It's not the hardness of the steel, it's the hardness of the carbides in the steel. The stainless razors themselves will not be any harder on a rockwell hardness tester than a carbon steel razor, and it's likely that they will be softer than vintage carbon steel razors that were intended for barbers and made with a hard temper.

Chromium carbides, Vanadium carbides, Tungsten carbides....all are extremely hard. But the steel overall is not, the carbides in it are. They are what give the wear resistance, not the hardness of the overall alloy.

Originally Posted by DaveW

It's not the hardness of the steel, it's the hardness of the carbides in the steel. The stainless razors themselves will not be any harder on a rockwell hardness tester than a carbon steel razor, and it's likely that they will be softer than vintage carbon steel razors that were intended for barbers and made with a hard temper.

Chromium carbides, Vanadium carbides, Tungsten carbides....all are extremely hard. But the steel overall is not, the carbides in it are. They are what give the wear resistance, not the hardness of the overall alloy.

Agreed, but you cannot separate the carbides from the alloy. The fact is carbon steel can easily be hardened to unbelievable Rockwell levels that are of course too brittle to be useful. SO CAN STAINLESS steel. The main advantage with stainless steel is its resistance to rust. Ceteris Paribis (all things being equal) if rust resistance is not necessary then a properly hardened and tempered carbon steel will outperform stainless in terms of toughness. The hardness can be very close but carbon is tougher - period. Where are those rust resistant shock absorbers on trains and cars - that's right they are all carbon steel for a reason. The rust resistance would certainly be appreciated in these applications but stainless steel (even the best alloys) could never be tough enough to spring back and forth a million times without fatigue. Carbon steel is still the king of toughness. Here is an example where stainless steel could never pass the toughness test.

I know you will enjoy this video of a Master Bladesmith Test. Only one type of blade will pass – san mai (Japanese) or Damascus (American) laminated carbon steel blades. Stainless steel need not apply.

1. Cut a 1” hemp rope in one swing.
2. Chop through a 2x4 twice.
3. Shave arm hair after these two tests.
4. Pass blade examination by a Master Bladesmith.
5. Bend the blade in a vice to 90 degrees without metal fracture.

I struggled with my Boker stainless blade when I first received it. After several tries it just did not do as well as its brother The King Cutter. I communicated with SRD and told them my problem. They suggested I send it back which I did. After receiving it back, I used it on about a five days' growth. Shaved like a charm. Used again this AM, the same thing. No harsh feeling on the face. Only smoothness. This was my first stainless after shaving with regular carbon blades for years. I shall buy at least another one.

Originally Posted by Gammaray

Agreed, but you cannot separate the carbides from the alloy.

Somewhere you're getting mixed up with hardness and separability of carbides from a diemaking or toolmaker's steel.

The rockwell test does just that, it tests the hardness of the entire alloy, and not just the hardest part of it.

Back to the original claim, that stainless razors are harder than carbon steel razors - it is not true. Stainless has carbides in it, depending on the alloy, probably different carbides for corrosion resistance. So does high speed steel, for a different reason (to increase the tempering temperature).

In terms of toughness (without regard to knife tests, etc), all you have to do is go to latrobe steel's page and look at their toughness charts for powder and non powder diemaking and high speed steels versus carbon steels. The carbon steels are not the toughest of the bunch. It's not that simple, and you really have to get down to the measured method. D2 is tougher than carbon steel in general, but at 18 degrees, it will not be. Same with A2.

But don't get away from the fundamental issue here, in the steels that are used for razors, a chromium, vanadium or tungsten carbide doesn't make the alloy harder than another alloy that doesn't have them.