Heat treatment for 102cr6 steel

R

robertpatachia

Joined
Feb 12, 2012
Messages
4
Hello it is possible to use the same heat treatment for 102cr6 as the 52100 (1475F +10 minutes soak)if not please please help me with the heat treatment at 62 hrc for wood carving knife
Thank you ,Robert
 
I just looked up the composition, and it looks quite similar to 52100. 1475f should work well.
 
robertpatachia said:
Thank you ,any advantage with subzero quench for this steel
Click to expand...

No. Using 1475f instead of 1550f results in only 0.8% of the carbon going back into solution, rather than the 1+%. You don’t get the retained austenite problem that cryo would solve.we keep the grain small with the lower temp, and carbide size is small and evenly distributed. Bearing do better with larger carbides, and some retained austenite. Not what we want, which is why we use this protocol.
 
Warren is right. Your post quench hardness out of the oil with the low temp protocol (1475f) should be 66-67HRC. If you use the 1550f temperature normally used for bearings, the post quench HRC will be lower, you will have more retained austenite, and a lot of brittle plate martensite. "If you see hardness gains with sub zero or cryo treating 52100, you need to rethink your heat treatment".
 
samuraistuart said:
Warren is right. Your post quench hardness out of the oil with the low temp protocol (1475f) should be 66-67HRC. If you use the 1550f temperature normally used for bearings, the post quench HRC will be lower, you will have more retained austenite, and a lot of brittle plate martensite. "If you see hardness gains with sub zero or cryo treating 52100, you need to rethink your heat treatment".
Click to expand...

I did charpy samples in the last batch for both O1 and 52100 at 1550f+cryo, to compare to the 1475f, non cryo protocol we typically use.
 
Would be interesting. While the sub zero will bump the hardness where it should be, and bring down the RA%, there still is the plate martensite factor that sub zero won’t help with. How much of a factor that will be is going to be interesting.

I appreciate the work. I appreciate Larrins chart on toughness, but for me, it’s slightly noisy. By that, I mean the chart should show toughness at a given hardness. All steels compared to one another should have the exact same hardness. Like 61hrc would be perfect to compare. I’m not tying to be critical of Larrin at all. He has done far more than necessary. Way above and beyond, so to speak. And a lot can be gained by that chart. I just think it should be “variable minimized”, and it just makes sense to compare them all at one hardness, of which 61 is usually used and easily attainable. But I do understand the samples were provided as he received them, and do not want to come across as judgemental.

It’s the work and posts from you 2 guys (and some others) that make this forum really enjoyable to catch up on.
 
Last edited:
samuraistuart said:
Would be interesting. While the sub zero will bump the hardness where it should be, and bring down the RA%, there still is the plate martensite factor that sub zero won’t help with. How much of a factor that will be is going to be interesting.

I appreciate the work. I appreciate Larrins chart on toughness, but for me, it’s slightly noisy. By that, I mean the chart should show toughness at a given hardness. All steels compared to one another should have the exact same hardness. Like 61hrc would be perfect to compare. I’m not tying to be critical of Larrin at all. He has done far more than necessary. Way above and beyond, so to speak. And a lot can be gained by that chart. I just think it should be “variable minimized”, and it just makes sense to compare them all at one hardness, of which 61 is usually used and easily attainable. But I do understand the samples were provided as he received them, and do not want to come across as judgemental.

It’s the work and posts from you 2 guys (and some others) that make this forum really enjoyable to catch up on.
Click to expand...

Initially, it was suggested to use Rc60, but then we lose site of which steels are suited to different hardnesses. Ie, is it better to use 3v, Z-tuff, or z-wear at Rc58, Rc60, Rc62, orRc64? If we only use Rc60, the advantage of using z-wear, M4 or V4e could be lost.

With the spreadsheet, it can be reorganized to rank different columns in ascending or descending order. I’ll think about ways to make comparisons easier.
 
See that is my point. “It is better to use these steels at “x” hardness”.

Who says so? It is just science to eliminate variables. I’m not bitching at you or Larrin, Warren. Not at all. I suppose it comes across that way online, but person to person I would do everything to prevent that.

I get the point. I want my CPM M4 at 64-65. I want my AEBL there, too, if I could get it there! That’s why I mentioned 61hrc. Maybe 62, or even 63??? Most all steels can get there. And then we can compare them apples to apples. I mentioned 61 because it is the toughness/strength meeting point of a lot of our knife steels.

For those steels that are often used harder, they could be included in the study, then we could compare toughness with a fixed hardness directly, then also look at see what toughness they are at higher hardnesses (if that steel is often used at it).

I’m being a Monday morning guarterback so to speak, and I want everyone to know that. You are putting in the effort. I just want to try and have equal footing to compare it all against.

And I have derailed the thread. Talking to myself here and to regain direction,

When heat treating a 52100 type steel, if the carbide (cementite) has been evenly distributed by normalizing at recommended 1650-1700f, and then thermal cycled to help keep the aus grain as small as we can, then using an austenitizing heat of 1475f and a good soak, we can expect highest as quenched hardness of 66-67+HRC, retained austenite at around 5-7%, and a mix of lathe and some plate martensite.
 
Last edited:
Toughness numbers are not always linear for a specific grade. It would be best if we could test all of these steels over a range of hardnesses.

Hoss
 
I saw the cru wear straight toughness numbers. Like you mentioned.....interesting.


But seriously, you can not compare (accurately) toughness when the hardness given is all over the place.

Yes, I agree. “It would be best if we can test all these steels over hardness ranges”. Yes!!!

But honestly they “should” be compared against a given hardness first. Go from there.
 
samuraistuart said:
I saw the cru wear straight toughness numbers. Like you mentioned.....interesting.


But seriously, you can not compare (accurately) toughness when the hardness given is all over the place.

Yes, I agree. “It would be best if we can test all these steels over hardness ranges”. Yes!!!

But honestly they “should” be compared against a given hardness first. Go from there.
Click to expand...


As the process evolved, we are trying arrange of hardnesses from Rc58-Rc64. (58,60,62, and 64.) we’ve been adding a high temper sample to compare as well. So, four or more conditions for most steels.

It doesn’t seem like bitching to me. The first two batches were sort of random, with length of cryo, cryo/no cryo, low/high temper comparisons. The last couple batched have been trying to fill in gaps to populate a comprehensive database with common steels over their useable range.
 
Hi Stuart I do not look after hardness gain i hope for great edge stability is 2,3 mm thick end 80 mm length with 18 degrees angle scandi bevel
Regards Robert
 
Yes it is best to have a range of hardness to compare all of the steels. I suggested 60 Rc if only one condition be tested but that hasn't always been followed, either intentionally or accidentally. 60 Rc is a round number and nearly any knife steel can reach it without an extreme heat treatment. The average Rc for custom knives has crept up over the years and some think 60 Rc is too low but that is what I picked. I agree with Warren that 58-64 Rc is a good range to target if possible. Keep in mind that we are attempting to build a more complete toughness database than has ever been available before. You can't go to the Crucible S30V datasheet and get toughness numbers for 58-64 Rc. Much less a comparison between different steel manufacturers. It will take some time but we are making progress.

The straight-line toughness of Z-Wear is a little puzzling. However, the two lowest hardness numbers came from the 1000°F tempers which had lower toughness. The third lowest was a cryo-free 400°F temper; if you remember the article cryo increased hardness but did not reduce toughness, which was somewhat surprising.
 
Larrin said:
Yes it is best to have a range of hardness to compare all of the steels. I suggested 60 Rc if only one condition be tested but that hasn't always been followed, either intentionally or accidentally. 60 Rc is a round number and nearly any knife steel can reach it without an extreme heat treatment. The average Rc for custom knives has crept up over the years and some think 60 Rc is too low but that is what I picked. I agree with Warren that 58-64 Rc is a good range to target if possible. Keep in mind that we are attempting to build a more complete toughness database than has ever been available before. You can't go to the Crucible S30V datasheet and get toughness numbers for 58-64 Rc. Much less a comparison between different steel manufacturers. It will take some time but we are making progress.

The straight-line toughness of Z-Wear is a little puzzling. However, the two lowest hardness numbers came from the 1000°F tempers which had lower toughness. The third lowest was a cryo-free 400°F temper; if you remember the article cryo increased hardness but did not reduce toughness, which was somewhat surprising.
Click to expand...

I’ll be getting some more z-wear to tease this out. I’ll use Rc58 through 64, and maybe higher if I can get that, using cryo/400f tempers, for applesto apples. I want to see what relatively lower austenizing temps and lower tempers, like 300f and 350f will do to toughness compared to the 400f standard tempers and higher aust temperatures. I don’t see a need to experiment more with high temper. Testing and in hand performance and feedback show the benefits of cryo/low temper for our uses.

I suspect we will see the expected drops in toughness as hardness goes up, when using comparable protocols. Stuart is right that there are too many variables to draw conclusions. We can either add more conditions to fill in gaps to try to answer these questions, or we can remove variables to get rid of the noise in the data. Both are valid strategies, but have different benefits/costs.
 
With datasheets from the steel manufacturers, they just don't show you anything that doesn't fit what they want you to know. As we add more steels we will have to come up with simplified methods for displaying information.
 
You must log in or register to reply here.
Back
Top