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Hi,

I am working with some New steel, and have issues with very coarse grain structure. The steel is european grade 130 CrV3 (close to w2).

 

I did 3 x normalizing, starting at just over unmagnetic on the first run, and just below unmagnetic at the last one. All three cycles allowed to air cool.

 

Quench at approx 820 deg. C in parks 50, preheated to about 40 deg. C.

 

Tempered 2 x 1 hrs at 230 deg. C.

 

Had a small warp, and tried straightning in a vise, straight after last anneal (still warm). Snapped very loudly, and revealed a super course grain in the fracture. I normally use steels like 1075CR, UHB20C, 1080CrV2 and 52100, but never had this happen before. 

 

What went wrong? Tips & hints appreciated.

 

Kind regards,

 

Mikkel

20210125_182847.jpg

Edited by Mikkel Hollnagel
Poor spelling
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Hello Mikkel,

 

I'm going to first get this out of the way, you are mixing the terms anneal and temper. When you say 2x anneal at 230°c, you are referring to tempering. 

 

Now, how are you monitoring your temperatures? I don't know this particular steel, but 820°c seems about right because of the chrome slightly raising the quench temp compared to plain carbon steel. So the problem would rather be in the accuracy of your temp measurements. You said you used a magnet for normalization. So how did you judge you were at 820° at the quench? Also, the first normalization cycle should be at higher temp to properly dissolve the V. Around 1600-1700°f is recommended for W2 if I remember well. 

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I'd start by going a bit hotter on the normalizing cycles.  Maybe start at 900C (higher would be OK, too), then end at about 800C for the third cycle.  

 

Also, what you are listing as "anneal" is actually a "temper".  I'm 100% sure you're English is much better than my Danish, but there is this one thing you may want to correct.  (Edited to note that Joël beat me to it as I typed.)

Edited by Jerrod Miller
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Hi Joel & Jerrod,

 

Thanks for posting. I always get the terminology wrong reg. Heat treatment, no news there (but kindly noted) :)

 

I sadly don't have any proper heat treatment oven,  nor IR-thermometer - so my low tech approach is bring the blade to non-magnetic in my gasforge in a dimly lit Room, and compare to a color chart. The i use that "look-up" as a point of visual reference/baseline.

 

You're probably right that my lack of accurate temperature control is the root cause. I just never had this issue before, on approx. 50 blades in misc. steels, but maybe chrome+vanadium is exposing my poor method more clearly, than the "simpler" steel i normally use?

 

Is there a resonably affordable way to measure blade temperature accurately (sub 150 USD if possible)?

 

Ohh, forget to mention that i use holding time of 5 minutes at quenching temperatur, for a 3mm / 1/8" thick blade.

 

Thx again for taking the time.

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You can use Tempilsticks (spelling?) to help judge the temperature of the blade, or you can try to regulate the temperature of your forge and monitor it with a thermocouple.  I recently bought a thermocouple and PID to help monitor things in my forge.  Theres a bit of information in this thread if you're interested.  

 

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14 minutes ago, Mikkel Hollnagel said:

Hi Joel & Jerrod,

 

 

There are two basic and better ways to measure your temperature. The easier to spot and most obvious way is the table salt, which melts at around 1474°f. The other way is using the decalescence. Watch videos on YouTube about decalescence/recalescence for more info. It is harder to spot than melting salt because there must be almost no ambient light. 

Edited by Joël Mercier
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For what it is worth, I could not find any compositional information on 130CrV3, but did find 135Cr3.  I saw it referenced as similar to W2, and I heartily disagree with that comparison.  

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Jerrod: The data sheet uses both names 135cr3 & 130CrV3 respectively - composition from the French supplier as follows:

 

 

Screenshot_20210125-195637_Office.jpg

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I saw that, but I don't think that is correct.  The second page of the sheet is the same as the first page, with that chemistry listed under 135Cr3 both times.  I think they have a glitch and are missing the second page with the actual 130CrV3 info.  Also, anything with a V in the name like that should have at least 0.10%V, and much more likely to have over 0.20%V.  

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Unlike Jerrod, I'm not a metallurgist but I would not attempt that steel unless I had a regulated heat treating over because of the high carbon content and complex metallurgy.

I don't know what the steel availability is in Denmark but I would recommend that you stick with a steel that you can handle with the forge that you have, like the 1070 and the 1080CrV2 (80CrV2?).

 

The size of the grain in that blade would indicate that it was overheated.  Not uncommon starting out.

 

Welcome aboard and keep working.

 

Doug

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