Getting started on big blades: differential 1075-1085 or 1095 thru tempe??

I haven't yet used 1084, but with all the hoopla, I fully intend to soon. However, I've been making swords out of 5160, and it's a darned good steel for swords. After all, if they make truck springs out of it you know it's gotta be tough. Would 1084 be better for swords? I don't know, we'll have to see. i think the bottom line is, if you know what you are doing with any modern steel, you'll get good results. With all of that said, if I were Vulcanite, I'd go with 1084, simply because I have a lot of respect for what Kevin recommends. Oh, and Rick too (of course!).
 
Lol... Thanks David... but I think you nailed it...

David Stifle said:
i think the bottom line is, if you know what you are doing with any modern steel, you'll get good results.
Click to expand...

The maker's ability has more to do with a good blade than the type of steel used. If I was shopping for a blade, the important question would be "Who made it?" rather than "What's it made from?"
 
Yep, that's basically it, except a propane torch might not be hot enough for thicker blades. You'd have to try and see. I haven't personally tried the torch the spine method, but it's covered in Wayne Goddard and David Boye's books. I must admit I find it odd that Boye recommended it for kitchen knives.
 
me2 said:
Generally a full quench means hardening the whole blade. A differential temper is reheating the blade differently along the spine than the edge, typically by placing the edge in water and heating the spine with a torch. The edge (really the whole blade) is tempered in an oven to the desired temperature/hardness, then the edge is protected in water while the spine is softened with a torch.

1075-1084 info can be found on Kevin Cashen's web site.
Click to expand...

have you tried this method? i have heard of it but it does not sound very logical. how do you control the temperature with a torch without invoving 1st and 2nd type of tempering embrittlness? for example: if the edge is in water which means most like is blow 100c, while the spine is heated to over 500c. and tempering embrittlement range at 300~400c. it seems there will be a zone on the blade that will remain arround embrittleness range(300~400c).
 
hammerfall said:
have you tried this method? i have heard of it but it does not sound very logical. how do you control the temperature with a torch without invoving 1st and 2nd type of tempering embrittlness? for example: if the edge is in water which means most like is blow 100c, while the spine is heated to over 500c. and tempering embrittlement range at 300~400c. it seems there will be a zone on the blade that will remain arround embrittleness range(300~400c).
Click to expand...

Your temps you're quoting are a bit high if you did mean them to be Celcius. Drawing the spine back might reach 500F to 600F and is done by visually checking the colors progress across the blade.


-Xander
 
yes, i did mean celcius. most of spring tempering demands temperature arround 460~520c, such as 5160, s5 and s7 etc. make 5160 an example. this type has an embrittlement arround 300c if i remember right, which is 570f something. (s5 is arround 570~610f. s7 is arround 570~900f. ) if the goal of differential tempering is to get a tough and springy spin with a hard edge, you have to temper the spin to get tempered troostite(a type of tempered martensite usually tempering between 375c~500c to get it). but then there is problem i was talking about in my last post. there will be a zone on the blade stay within the embrittlement range.

of course, there are steels that does NOT affected by tempering embritlement significantly. but this embritlement is common enough in types of knife steel people using everyday. its not unusual to see makers claim his 5160/s5/s7/l6 blade has a edge of 60hrc and a differential tempered spin of 47~48hrc. that means the spin was tempered above 800f. mean while there is an ensured embrittle zone on the blade.i do not mean to turn down or criticise anyone, just to state my point of view. and i am pretty sure someone will find it useful.
 
hammerfall said:
yes, i did mean celcius. most of spring tempering demands temperature arround 460~520c, such as 5160, s5 and s7 etc. make 5160 an example. this type has an embrittlement arround 300c if i remember right, which is 570f something. (s5 is arround 570~610f. s7 is arround 570~900f. ) if the goal of differential tempering is to get a tough and springy spin with a hard edge, you have to temper the spin to get tempered troostite(a type of tempered martensite usually tempering between 375c~500c to get it). but then there is problem i was talking about in my last post. there will be a zone on the blade stay within the embrittlement range.

of course, there are steels that does NOT affected by tempering embritlement significantly. but this embritlement is common enough in types of knife steel people using everyday. its not unusual to see makers claim his 5160/s5/s7/l6 blade has a edge of 60hrc and a differential tempered spin of 47~48hrc. that means the spin was tempered above 800f. mean while there is an ensured embrittle zone on the blade.i do not mean to turn down or criticise anyone, just to state my point of view. and i am pretty sure someone will find it useful.
Click to expand...

Good question, Hammerfall... It makes sense, I would like to find out, too... and I will.

I found this article... http://www.industrialheating.com/Articles/Column/34f38218045ae010VgnVCM100000f932a8c0____
 
Last edited:
hmm. okay, so hammerfall is saying that after you full quench the blade and heat the spine w/ the edge in water, there will be an area in between the spine and edge somewhere that will be brittle, and more so than the hardened edge apparently?

Wouldn't this always be an issue w/ any process of differentially tempering?

For a boning or filet knife, where you don't have to worry about shock, it would be pretty slick to have a really hard edge bonded to a flexible spine via some sort of differential tempering process. maybe to get this effect, you could temper the whole blade to a lower hardness, then torch just the edge only and keep the spine cool w/ a heat sink paste and then quench just the edge to get a super hard edge...

I think that all swords, cept for katanas, are/were through tempered following a full quench since the through temper is the best way to get the best compromise between hardness and toughness in an edged tool subjected to shock. I think I'll skip any sort of differential temper w/ the large heavy knives. So all I need is a oven capable of about 500f to temper and a big propane torch to heat the blades before the full quench.
 
Last edited:
If what I'm interpreting from this is correct, a blade fully tempered at 220C(430F) would have more impact toughness than that same fully tempered blade with the spine torched to 315C(600F)
 
Found this on "That Kevin Guy's" site:

Recommended Working Sequence For 1084:
...Grinding or Machining:
(I guess this is presuming you are starting w/ annealed steel ground to your likeing.)

Hardening: Austenitize- Heat to 1500 °F (815 °C). Quench in water or brine. Oil quench sections under 1/4 in. (6.35 mm) thick



Tempering: As-quenched hardness of approximately 65 HRC. Hardness can be adjusted downward by proper tempering
 
Rick Marchand said:
If what I'm interpreting from this is correct, a blade fully tempered at 220C(430F) would have more impact toughness than that same fully tempered blade with the spine torched to 315C(600F)
Click to expand...

Would both blades in your example have the same edge hardness??
 
edge hardness is determinded mostly by quenching temperature and tempering temperature x time. 2 knife of 5160 of same quenching temperature. one fully tempered at 180 twice for 2 hours each time. another one fully tempered at 180 twice for 2 hours each, then torch tempering the spin while the edge remain in water. both blade should have the same or close enough edge hardness.
 
and in reality you may not find embrittlement much of a problem under most of normal uses. don't want offend anyone, but i have handle knives battle field proven by some of the best soldiers in the world, yet that very knife he so trusted somehow was tempered arround embrittlment range. but his experience with that knife is quiet good and legendary. that made me believe sometime i just worry too much. luck, or say God decide everything for us already...

anyway, this 2 type of embrittlement is no way to fully rid off, and exists in most of steel. but its effect can be reduced to cause no significant damage by alloying, reducing the junky impurity such as P, As etc... i will save your time and stop posting wall of text over here. just remember these 2 range: 250~400c, 350~570c. evil and bad luck usually lurking somewhere in there.
 
Hammerfall, Rick, et al: this conversation brings me back to when I did my "Intrinsic Motivation" destruction test knife. This page has the video and the resulting crack, page #1 for the actual draw back: http://www.bladeforums.com/forums/s...nife-WIP/page6?highlight=Intrinsic+motivation

I wonder whether the knife cracked they way it did as a result of drawing back the spine in such a manner. I know I wasn't absolutely perfect with the process. But, I do know that my heat treat and whole blade temper were spot on. Maybe if I had not done the draw back whether the blade would have performed better.

Thought provoking thread!
 
damn i can't see that video now. i had to run an illegal program by passing the firewall to watch it. i will watch it later tomorrow with another IP address.
 
talk about hardened edge and spring spin. there are some swords manufacturer using induction heater to do it. first quench and temper to get the spring structure(need to be higher than the first type of embrittle range) or salt bath to get bainite if you like. then set up the frequency of the induction heater arround 8khz, that will get you a 6~7mm heat pentration. now go and heat the edge with it. it takes only a few seconds before the thin edge reach up to 800~900c. while most part of the thick spine still remain under 500c. this way you do not need to worry about tempering embrittlement since the first type won't occure again if your first tempering already by pass its range.

sounds complicated, but once the equpitment is there its seem to be the best way to mass product. quiet nice hamon as well. and need not wait the clay to dry like traditional method.down side of this method is that you cannot really manage the quenching temperature accurately. the quality of the result is mainly base on worker's experience with the equiptment. and it is quiet dangerous, high frequency em waves leakage has a chance damaging eyes and balls etc... in usa owning and using such equiptment required license, safety gears, and professional workers. over here, in many underground factories you see guys running these thing half naked while eating lunch!!! thats the ugly side of a still developing country, however such uglyness can get hard thing done easy lol. quiet like 1930s america.
 
Last edited:
I knew edge hardening could be done with induction heating. I did not know about the health hazards. :O My reading indicates the 2 step temper embrittlement can be avoided by not allowing the part to linger in the critical temperature range. This is done by either not heating that high to start with or by heating above it and then quenching after tempering. At the higher temperature, the offending elements have enough energy to go where ever they want, and not just end up at the grain boundaries. At the lower temperature, they don't have enough energy to move much of anywhere in the time used for tempering, 1-2 hours or so.

Hammerfall, I have not used that method. The few blades I've done with differential hardness were done by edge quenching in shallow oil or water. Even then it was only 3-4 blades. The 1095 ones did show a nice quench line though.
 
I don't have a whole lot of experience with different steels yet, but I can tell you that I ordered a bunch from Aldo, the price was great, and somehow it had processed, shipped, and was at my house the day after I ordered it.
 
The Kevin guy is not a metallurgist but is a VERY fine blade maker with VERY high amounts of metallurgy knowledge. On rare occasions it takes a real metallurgist like myself to give him correct metallurgy info !!
The discussions about a possible brittle zone in edge quenched are a moot point .While edge quenched is very popular it can be shown that it's not as good as full quench.
Other than 1080/1084 for beginner choppers ,5160 and 9260 will work fine . When you become a very experienced maker then you can use CPM 3V ,that makes a VERY good chopper !
 
You must log in or register to reply here.
Back
Top