Hardness Range?

[dougk16]

I've noticed some manufacturers giving a range for the hardness of their blades, say 58-60 RC. Does this mean that it's a crapshoot as to what blade you'll get, or rather that the business part is 60 and the rest of the blade is 58 to maximize toughness?

 

[Bali105]

its the range the blade will be in. Like if you're looking at precision caliper, it might say "accurate to +-.001 inches"

 

[Horn Dog]

It just means that the hardness is somewhere between 58 and 60 Rc, which is plenty hard enough for good edge retention.

 

[John R. Fraps]

A 2 point range, 58-60 Rc isn't much of a range on a knife that, who knows who heat treated, that, if accurate, is not at all a bad range.

The only heat treater I have ever done business with who was willing to, when I asked for 59-61, stated 59.5 Rc on the rectangles I sent him to HT that would someday be blades, and I have sent as many as 170 at a time, plus other steel to be right at 50-ish for slipjoint springs...that were stated to be right there, was Paul Bos.
He tests every piece he does....every one has that tiny indentation in it.
I am not the least concerned about the steel he heat treats for me....ever.
And since I have a pretty good feel for how the steel is HT'd somewhat by how it feels when I grind it....always barehanded to keep it from getting hotter than my fingers can stand....I'll just say he knows his profession as well as anyone I know in the knife industry...commercial, handmade, self-heat-treated, forged....anyone....period....and there are some mighty knowledgeable makers and HT-ers and others out there....
Paul, to a number of makers, including me, is the "gold standard" in heat treating "stainless".
Sorry I got off on a tangent....opinion is 58-60 is a pretty narrow range, not bad at all.

 

[Jeff Clark]

58-60 is a pretty tight range for a high volume product. Even with good ovens it is hard to get a whole batch up to your hardening temp without leaving them too long then cool them off rapidly enough to harden them. Next you have to get them all up to the desired tempering temperature for the right interval. You may also want to cryo treat them. The large batches are demanding. You can probably get some knives in a batch that are 58 and some in the same batch that are 60. If something goes wrong you might get a batch where some blades are 56 and others are 58. With a lot of companies these will be passed through to the customer as good enough.

 

[mete]

Specs calling for a 2 point range is standard in the steel industry.

 

[dougk16]

Thanks for all the replies. The reason I ask is cause I read some article once stating how much of a difference 2 degrees on the rockwell scale can make. But what I understand from the replies is that the difference is negligible enough that for for all intents and purposes I can just say it's 59 and leave it at that.