heat treat/ temper questions on S35VN

dogwood dan

dogwood dan

Joined
Aug 19, 2011
Messages
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1)my back ground is working with carbon steel mostly o-1
2) a this point I am working on 1/16" filet knives
3) I am prepared to be told that to get the properties I want I should use another steel
4) salt water guides are a big part of my filet knife business (so I need to work in stainless)
5) I have been getting customers that want 59-60 rc
6) what I have been producing is 57-58rc (by the crucible data sheet)

is a 59-60rc practical on a hard use filet knife? if so
is it practical to not temper a steel like S35VN, and use it as quenched? this question goes against every thing I have learned but there is a lot I have not learned. if not
what is the best way to achieve a 59-60 rc on s35vn

my process at this time
I heat teat fiol wrapped (with something to burn off the 02 in side) at 1900 F

plate quench giving

temper at 450F

all the data have found gives me temper temps for rc57.5 and lower


Thank you for your time and help

Dan
 
dogwood dan said:
is it practical to not temper a steel like S35VN, and use it as quenched? this question goes against every thing I have learned but there is a lot I have not learned.
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You're right, tempering is done not only to reduce hardness, but to convert retained austenite to tougher martensite. The PDF Stacy linked to shows tempering regimens with final hardness as high as 61Rc.

I haven't worked with S35VN myself, but from all reports it should be an excellent choice for a filet knife.
 
I make a lot of fillet knives from CPM-S35Vn. It makes a great knife. Edge retention is better than CPM-154. I find Rc 59-60 as the optimum target for edge life vs sharpening ease.
I have got Don Agee, a big time fisherman and good knifemaker to try using it. He hasn't had any field trials yet, but if it works for him, I believe it will work for anyone. Don fillets a fish and leaves a skeleton and two fillets. He uses two knives, one stiff as a cleaver and one slightly flexible. He has always used .125 to .150" steel stock. He hates my "wiggly" .060" thin fillet blades :) . About a year ago, I got him to start using .080-.100" CPM-154 steel and he was really surprised on how much better they cut. He just did a batch of .09-.100" CPM-S35VN blades, and they really look great. I think we will have to go fishing for tuna soon, and try them out.
 
Dan,
HT on these type stainless steels is where the pros shine. Send a batch of blades to Peters, and give them the target hardness. They take it from there. The blades come back looking nearly like they left your shop, and dead straight. Every one is hardness tested. It takes about ten knives in the batch to make it work out as affordable, and when you get to twenty or thirty, it gets downright cheap. They have a dedicated knife guy, Brad, who really knows his stuff.
 
bladsmth said:
They have a dedicated knife guy, Brad, who really knows his stuff.
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They (Peters') also include cryo treatment, which is very good for high-alloy steels like S35VN. Even if you don't use their service, give Brad a call or chat with him if you see him at a knife show. He's a cool guy and loves to talk knives.

I hope I'm not out of line by mentioning this... but I have it on good authority that Brad actually figured out and wrote up the HT protocol for knife use on at least one recent "super steel", at the request of the folks who make it.
 
I would definitely recommend that you start using 1950-2000 for your austenitizing temperature. In our testing we've found that blades austenitized at 1900 are very brittle even after tempering (despite being less hard). Crucible's "recommended heat treat" (from the data sheet) gives nice hardness and toughness.

Our heat treat is: austenitize at 2000 then temper twice for 2 hours at 600 (no cryo). Blades come out right around 59 (as per the data sheet).
 
North Arm, have you tried cryo ?? That should be even better.

Dan, you must always temper after quench !!!
 
We haven't yet, it is something we will definitely experiment with at some point. So far the feedback we've received on the steel (from a couple of the chefs who tested our 8" chef's knife for us) has been : way better edge retention than most other knives they've used, and still easy to stone sharpen. When we look into cryo we'll have to try to figure out if the increased hardness affects sharpenability and if so, weigh the pros and cons.
 
So would tempering at 1000 be too much. The data sheet says "for optimum stress relieving" temper at 1000. The chart shows at that temp it would be around 59. I am looking for maximum toughness.
 
Stacy, I find this discussion on S35VN interesting. I made several knives, skinners, hunters and filet knives from it and had Bos heat treat them to 60-61 and they were fine. I did make 3 recently for an individual to his drawings and sent them to Bos and requested 60 RC that the customer requested and I guess something in the process was not right because they would not hold an edge. I do not use Peters because being a part time maker, I usually do not have enough blades at a time to be as cheap as Bos is.
 
ZWcustoms said:
So would tempering at 1000 be too much. The data sheet says "for optimum stress relieving" temper at 1000. The chart shows at that temp it would be around 59. I am looking for maximum toughness.
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I don' think it would make the blade soft if that's what you mean. The data sheet HT chart is accurate; if you follow the temperatures they list you will get the hardness they specified for those temperatures. If I remember the data sheet correctly corrosion resistance is affected when tempering at such a high temperature.

-mike
 
Walt2 said:
Stacy, I find this discussion on S35VN interesting. I made several knives, skinners, hunters and filet knives from it and had Bos heat treat them to 60-61 and they were fine. I did make 3 recently for an individual to his drawings and sent them to Bos and requested 60 RC that the customer requested and I guess something in the process was not right because they would not hold an edge. I do not use Peters because being a part time maker, I usually do not have enough blades at a time to be as cheap as Bos is.
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Hey Walt,

That is sort of odd, I'd be interested in hearing more (we try to learn as much as possible about S35 because we use it so much). Did you confirm the hardness was in fact the requested 60HRC when they came back from HT? What was the approximate angle of the edge / thickness behind the edge?

thanks!
mike
 
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