Heat treat

G

Gradyw

Joined
Jan 23, 2017
Messages
450
Can you heat treat a knife twice? Like after you've finished it if you wanted it harder could you start over the heat treat process? I've tried googling some information on this but didn't have any luck
 
I re-hted a test blade(to be sure - it's a naked blade without handle) multiple times quite often. Sometime it has actual sharp cutting edge - of course for some steels this require higher ht skills.

The more info you provide (steel type, hrc target, etc), other/I can provide more in depth feedback/guidance.
 
Yes, you can.

That said, chances are quite low that you could do a better job than the factory did. You don't have their equipment, skill, options, experience, process or abilities.
 
how about m390 that is 58-61hrc (thats the wide range, but thats what benchmade said) can someone re heat treat that to 62hrc? and who has the capability to do that to m390 thats already been HTed? its a griptilian blade. would that be too thin?
 
Last edited:
Why? Just cause? Or is there some actual performance issues / concerns you feel it's not hard enough?

BM CS won't do it just because but if there are actual performance issues with the blade they will shoot it for you if you send it in. They did this for me on a 710, tested near the edge and on the tang then included a full report when returning it to me (there turned out not to be any hardness issues).

The chances of you noticing ANY difference from m390 at 58 vs @ 62 on a small folding EDC type blade are slim to none. Again if you feel there's a real issue contact them with your concern but sending the blade out for a re-heat treatment almost surely isn't gonna net you anything but a loss of your hard earned money and time without the knife in your pocket.
 
re-ht m390/20cv to 62rc should be simple for those have setup to ht air/oil hardening steels. Unless major screwed-up 1st hardening or hot-working/forging, most blade can be rehardening w/o annealing first.

Warping is mostly due to un-even (asymmetrical) distribution of steel (blade grind, sharpening bevel, sloped spine, large divots, so on...) and also from un-even cooling within austenite to martensite transformation phase zone. As for harden or re-harden blade with an existing cutting edge - since sharpening bevel is far from perfect symmetrical, so with reasonable good sharpening bevel, just grind edge back to around 0.005" should be fine. *note - bacon edge is mostly caused by edge drastic cooled ahead of upper/thicker part. Leaving edge thick minimize drastic cooling differences and consequentially a good margin for establishing center line (edge) when after-ht pre-grind edge is slightly crooked.

As for why change blade strength(partially hrc)? Well, when edge dulled/damaged by: rolled -> up hrc, chipped -> lower hrc, weared (slow edge loss of edge via combination of factors) == leave it be. ht-quality can slide roll-chip window by 2-5rc. When hrc is going below 60rc, performance difference will diminish esp in micron activities, going below 55rc typical no diff. Tasks+geometry+sharpening are mission-critical in importance as well.

Mo2 said:
how about m390 that is 58-61hrc (thats the wide range, but thats what benchmade said) can someone re heat treat that to 62hrc? and who has the capability to do that to m390 thats already been HTed? its a griptilian blade. would that be too thin?
Click to expand...
 
Cereal_killer said:
Why? Just cause? Or is there some actual performance issues / concerns you feel it's not hard enough?

BM CS won't do it just because but if there are actual performance issues with the blade they will shoot it for you if you send it in. They did this for me on a 710, tested near the edge and on the tang then included a full report when returning it to me (there turned out not to be any hardness issues).

The chances of you noticing ANY difference from m390 at 58 vs @ 62 on a small folding EDC type blade are slim to none. Again if you feel there's a real issue contact them with your concern but sending the blade out for a re-heat treatment almost surely isn't gonna net you anything but a loss of your hard earned money and time without the knife in your pocket.
Click to expand...
because if its 58 HRC its not optimal. i need to be able to cut all the cardboard up without sharpening through the job. it saves lots of time. time is money. i dont know what the hrc is, and because its such a wide range, id like to dial it into optimal if at all possible, as you mentioned i should probably get it tested first. someone had mentioned such a HT job is only around $30 for s35vn (it was a sebenza blade), so i didnt think it to be such a waste of money if its under $60 id be fine with it.
 
Mo2 said:
i need to be able to cut all the cardboard up without sharpening through the job. it saves lots of time. time is money
Click to expand...

Doesn't seem like any problems exist to me... [shrugs] IDK.

This is an actual job? Like as in you go to it daily and get paid money for doing it? I know this is a KNIFE FORUM and we all take great joy in our super awesome nice knives but maybe it's time to think about a different tool for said specific job... A replaceable blade razor knife is THE tool for breaking down cardboard by hand. No actual knife, no matter the cost / size / perceived value / material will ever beat a replaceable bladed razor knife at such a job, ever. Save your beloved [and expensive] pocket knife for the less specific jobs and leave the work to the dedicated work-tool made exactly for such tasks.


What if you do the job of cutting the cardboard in the morning then you need a super sharp knife for some important, possibly life-saving task later in the afternoon? Then what?! This thread sounds like a plea for help finding the correct tool for the job at hand, not trying to cobble up a way to get the tool you already have to just barely be able to make it threw the first job you ask of it.

Just my 2¢ but I surely wouldn't ask a good knife to break down cardboard and I'm 110% certified a knife and tool junky.
 
Cereal_killer said:
Doesn't seem like any problems exist to me... [shrugs] IDK.

This is an actual job? Like as in you go to it daily and get paid money for doing it? I know this is a KNIFE FORUM and we all take great joy in our super awesome nice knives but maybe it's time to think about a different tool for said specific job... A replaceable blade razor knife is THE tool for breaking down cardboard by hand. No actual knife, no matter the cost / size / perceived value / material will ever beat a replaceable bladed razor knife at such a job, ever. Save your beloved [and expensive] pocket knife for the less specific jobs and leave the work to the dedicated work-tool made exactly for such tasks.


What if you do the job of cutting the cardboard in the morning then you need a super sharp knife for some important, possibly life-saving task later in the afternoon? Then what?! This thread sounds like a plea for help finding the correct tool for the job at hand, not trying to cobble up a way to get the tool you already have to just barely be able to make it threw the first job you ask of it.

Just my 2¢ but I surely wouldn't ask a good knife to break down cardboard and I'm 110% certified a knife and tool junky.
Click to expand...
Thanks for the 2¢ as you made some really good points to think about.
 
Cereal_killer said:
Doesn't seem like any problems exist to me... [shrugs] IDK.

This is an actual job? Like as in you go to it daily and get paid money for doing it? I know this is a KNIFE FORUM and we all take great joy in our super awesome nice knives but maybe it's time to think about a different tool for said specific job... A replaceable blade razor knife is THE tool for breaking down cardboard by hand. No actual knife, no matter the cost / size / perceived value / material will ever beat a replaceable bladed razor knife at such a job, ever. Save your beloved [and expensive] pocket knife for the less specific jobs and leave the work to the dedicated work-tool made exactly for such tasks.


What if you do the job of cutting the cardboard in the morning then you need a super sharp knife for some important, possibly life-saving task later in the afternoon? Then what?! This thread sounds like a plea for help finding the correct tool for the job at hand, not trying to cobble up a way to get the tool you already have to just barely be able to make it threw the first job you ask of it.

Just my 2¢ but I surely wouldn't ask a good knife to break down cardboard and I'm 110% certified a knife and tool junky.
Click to expand...
It's just inconvenience. You straight up have to stop what your doing to sharpen.
Thats all
 
Cereal_killer said:
Why? Just cause? Or is there some actual performance issues / concerns you feel it's not hard enough?

BM CS won't do it just because but if there are actual performance issues with the blade they will shoot it for you if you send it in. They did this for me on a 710, tested near the edge and on the tang then included a full report when returning it to me (there turned out not to be any hardness issues).

The chances of you noticing ANY difference from m390 at 58 vs @ 62 on a small folding EDC type blade are slim to none. Again if you feel there's a real issue contact them with your concern but sending the blade out for a re-heat treatment almost surely isn't gonna net you anything but a loss of your hard earned money and time without the knife in your pocket.
Click to expand...
I'm really curious about you saying there not be any noticeable difference in going from 58 to 62 rc with m390. I'm by far a blade or steel expert but I have been doing a lot of research lately and that to me sounds like it there should be a huge difference taking it to 62 rc if it is 58. Am I wrong? Do all the knife nuts that I've been reading their comments just make way to big of a deal about these things?
 
Gradyw said:
I'm really curious about you saying there not be any noticeable difference in going from 58 to 62 rc with m390. I'm by far a blade or steel expert but I have been doing a lot of research lately and that to me sounds like it there should be a huge difference taking it to 62 rc if it is 58. Am I wrong? Do all the knife nuts that I've been reading their comments just make way to big of a deal about these things?
Click to expand...
i dunno, seems like there very well could be http://www.bladeforums.com/threads/...ed-on-edge-retention-cutting-5-8-rope.793481/

but without two exact same blades at different hrc ratings are tested dunno for sure.
 
Mo2 said:
because if its 58 HRC its not optimal. i need to be able to cut all the cardboard up without sharpening through the job. it saves lots of time. time is money. i dont know what the hrc is, and because its such a wide range, id like to dial it into optimal if at all possible, as you mentioned i should probably get it tested first. someone had mentioned such a HT job is only around $30 for s35vn (it was a sebenza blade), so i didnt think it to be such a waste of money if its under $60 id be fine with it.
Click to expand...

Is it a hollow ground Griptillian? I loved mine for its relatively thin grind.

To solve the problem with cardboard, have you tried lowering the edge angle and finishing with a coarse stone? Maybe 10 degrees per side or less, finished on a DMT coarse or a medium grit Norton Crystalon?
 
You must log in or register to reply here.
Back
Top