Different steels and ease of sharpening

[mrcharly]

My Mora 106 needed major sharpening, after I'd used a coarse waterwheel on a grinder to reprofile it (broken tip, chipped blade). SAK needed sharpening, plus MrsC's favourite kitchen knife.


Started with the SAK, that didn't need much. Frustrating minutes later, it was not sharp. Barely able to shave a single hair from arm.


Put it to one side and picked up the Mora. Blast, i'd put it away wet from grinding. A couple of minutes later, the Mora was done, finished on 1000grit and shiny, leaving bald patches on my arm.


The cheap stainless kitchen knife took a couple of minutes to get a decent working edge.


Back to the SAK.Eventually managed to get it nearly sharp enough to reliable shave an arm, after working hard and stropping.


So, the knife that was as rough as can be was really quick - the softish SAK was terrible, really, really hard work.


Is it just the hardness of the steel that makes the difference, or is it something else? I was using a 250/1000grit waterstone.

 

[ged]

[WRONG]
If it's a genuine SAK it's most likely
[/WRONG]

12c27 stainless steel, which was developed for razor blades.
There's nothing wrong with it, and I've never known it to cause any particular problems. It's no S30V but I still like it.
I have quite a number of 12c27 blades and I rarely need to sharpen them, but then I don't abuse them.
What kind of abuse do you give yours?

I've never used water stones on any stainless blade. Usually all mine need is a quick strop anyway.

Putting the Mora wet sounds like a learning experience...

 

[mrcharly]

It's a SAK marine and I've wondered if the blade is some variant of stainless that is more corrosion resistant. It is a pig to sharpen - I've had other SAKs and not found them this hard.

Question still stands tho'; is it just about hardness? Opinels are a doddle to sharpen, whether they are stainless or carbon.

 

[ged]

It's a SAK marine and I've wondered if the blade is some variant of stainless that is more corrosion resistant. It is a pig to sharpen - I've had other SAKs and not found them this hard.

I don't know the 'Marine'. There's a 'Skipper' (Victorinox product code 53663) and a 'Helmsman' (Victorinox product code 53664, also apparently sometimes called the 'Mariner'). Is yours one of those? I think both have serrated blades, which might be a challenge on your water stones.

In a quick search I've found a few sites claiming to give 'specifications' for these products, but nothing which goes so far as talking about the blade material and the characteristics of the material.

Question still stands tho'; is it just about hardness? Opinels are a doddle to sharpen, whether they are stainless or carbon.

No, it isn't just about hardness. There's wear resistance too, and that's probably more important from the point of view of sharpening, and there's edge geometry.

All the same, I've never thought of 12c27 blades as difficult to sharpen - even the serrated one on my 'SwissTool' and the part-serrated one on my 'Soldier'. I use one of these to sharpen the serrations.

 

[mrcharly]

Hmm you are right, it is the skipper.

No serrations left on my blade - they were shallow and only on one side. Wore them away long ago.

 

[Hibrion]

It might be more to do with the grind than the steel. The smaller blade and the flat grind on the sak might have thrown you off a bit. I find some very thin blades more difficult to sharpen than others purely because of the grind and the way I sharpen.

 

[C_Claycomb]

Victorinox does not use Sandvik 12C27 for its blades. Dunno where that idea came from, but it isn't so. Boker offer something similar that does use 12C27, and the difference is huge.

There may have been some changes over time, but they seem to have an idea that 56HRC max is the best hardness.

http://www.swissarmy.com/ca/content/sak-faq
Q. What is the makeup of steel?
A. All Victorinox knives are high carbon, stainless, first grade, A-quality stainless steel, x 50 CrMo. They are tempered to a 55-56 HRC hardness for optimum edge retention.

http://www.pizzini.at/info_sak_engl.htm#Steelinfo

After a sophisticated hardening process at 1040°C and an annealing temperature of 160°C the blades achieve a hardness of RC 56.

Material	for	Shortname	C (%)	Cr (%)	Mo (%)	V (%)
1.4110	Blade	X55CrMo14	0,48 - 0,6	13 - 15	0,5 - 0,8	< 0,15
1.4021	Spring	X20Cr13	0,16 - 0,25	12 - 14
1.4031	Tool	X39Cr13	0,36 - 0,42	12,5 - 14,5

I still have the SAK Camper I bought as a child of 8, had it now for over 30 years and the blades look almost as they did when I bought it. I quickly discovered that it didn't matter if I succeeded in making it sharp because as soon as I cut anything it would be dull again. So, I have almost always carried it just for the tools, and carried a second, single blade knife, for actual cutting.

 

[ged]

Victorinox does not use Sandvik 12C27 for its blades. Dunno where that idea came from, but it isn't so. ...

Crikey, you're right! The things you find out after so many years!

It seem like Sandvik did at one time supply stainless for springs and other parts, but not for the actual blades.

Apologies for the misinformation, time to edit a post...