Thread: RC hardness of Stainless blade - need opinions

Hi Guys,

Just wanted to ask a question regarding the Rc hardness of some razors I'm making. My steel is Bohler N690 stainless steel, other custom makers use/have used it for straight razors, namely Mastro Livi and I think all would agree that for a stainless blade this is a very good, fine-grained choice of steel to use.

My question relates to the final hardness of this steel after a triple temper at 200C, my spec sheet on the steel indicates that a final hardness after tempering would be 58-60 Rc - So I'd like to know if on the lower end of that estimate, if 58 Rc for a stainless blade is acceptible in a straight razor? Is that hard enough to maintain a good edge? Or would it be preferred to have a hardness of around 62 but with a more brittle blade (so then not tempered)? I've read that razors can range from 58-65 Rc, but what are your thoughts on N690 at a hardness of 58,59 or 60 Rc? - is it much of a muchness or a real factor to be concerned about? And then out of interest, does anyone know what hardness a Livi N690 blade is rated at?

(My blades will be hardened in a vacuum furnace at 1080C followed by an oil quench and then sub-zero treatment in liquid nitrogen, and then triple tempered at 200C.)

Thanks guys for any insights into this.

Cheers,
- Mike

Hey guys, sort of answered my own question here. Found a few links talking about rockwell hardness of blades and it seems as I suspected, that 58 and up is pretty acceptable. On my stainless blades, I'm thinking 59-60 is actually just about right, so I'm pretty happy with that.

Cheers,
- Mike

I read your question yesterday, but felt any answer I gave would not be based on my own knowledge. I do know that stainless blades are generally not as hard as carbon ones. They just have a different abrasion resistance.
Quite interested to see these blades of yours though! Good luck!

Thanks Ben for writing something anyways appreciate that.
But yeah, got some answers on another forum (WSW) so I'm good now. And heat treatment of my blades should go down perfectly.
I think my razors will appeal to quite a few folks, at least I'm making them from a point of what I want/am looking for in a custom razor, and I hope some other guys like what I like... (but let it be known how hard it is to create something 'new' when it comes to straight razors, wow.. I think one can only ever aim to 'reinterpret' what's been made before, and well that's basically what I'm doing.)

Thanks again,
Cheers,
- Mike

I'm only on my second & third blades, but I'd have to agree...make what you would like from a razorsmith and folks will like them. I'm still trying to decide what steel to work with once I finish up on these two. Been working with 1095 and have been considering using O1, but I do like the idea about stainless. Something just doesn't make since about us using a high carbon steel blade in a wet environment. It's an oxymoron if you ask me...

Let me know when they're ready. You've got my interest now! Love to try one out.

i am going to be upping the temper a bit on my test razor inn CPM154 to see if i gain smoothness at slightly softer RC
as it gets good and sharp but i i am wanting to keep seeing if i can make things better

This seems to be one of the places where a microscope can
help discover the correct level for a specific steel.

Too hard and micro chipping might be an issue.
Too soft and the blade is only sharp for half a shave or less.
Too hard and the honing time between grits gets too long.

In the Army Artillery we used to bracket a target.
Then split the difference dialing in on the target.
Try for too hard, too soft and then split the
difference, and split the difference again and again.
No need to know the RC hardness just the temper
timing tables for you and your shave test results.