Forging D2

[allenkey]

Once the blade is at forging temp it’s no longer hard from heat treating. When it reaches temp the martensite has been converted to austinite.

Not completely though, right? not without a full anneal? Don't get me wrong... lol... I know it doesn't retain its complete hardness at ~1400/1500 degrees. I hope I didn't sound like I was saying that xD

Edit: Don't mind me. I'm just going to go read Larrin's annealing article again

 

[JTknives]

Not completely though, right? not without a full anneal? Don't get me wrong... lol... I know it doesn't retain its complete hardness at ~1400/1500 degrees. I hope I didn't sound like I was saying that xD

Martensite converts back over at around 1400° so there would not be any left to induce hardness. What do you think anealing is? You take it up to X temp and let it cool at x rate. The reasion you cool it slower is it keeps it from hardening agian.

 

[DevinT]

There’s a difference between forging and proper

Not completely though, right? not without a full anneal? Don't get me wrong... lol... I know it doesn't retain its complete hardness at ~1400/1500 degrees. I hope I didn't sound like I was saying that xD

Edit: Don't mind me. I'm just going to go read Larrin's annealing article again

Annealing before heating something up to forge does not make it easier to forge.

Hoss

 

[allenkey]

Martensite converts back over at around 1400° so there would not be any left to induce hardness. What do you think anealing is? You take it up to X temp and let it cool at x rate. The reasion you cool it slower is it keeps it from hardening agian.

Well honestly, just wish I never spoke, lol. I was trying to rationalize why leaf spring does infact feel harder to forge than other barstock (because it is something I noted myself) but this is why I mostly lurk. Probably just has to do with the fact some leaf springs are 1/2" or thicker versus the barstock I buy that is around 3/16" lol

Thank you for being cordial though. Not trying to mislead anybody!

 

[DevinT]

Correct forging of D2 can break up some of the larger carbides creating a better structure. However, the forging temperature range is narrow and improper forging of D2 is more likely for most smiths.

Hoss

 

[DevinT]

Well honestly, just wish I never spoke, lol. I was trying to rationalize why leaf spring does infact feel harder to forge than other barstock (because it is something I noted myself) but this is why I mostly lurk. Probably just has to do with the fact some leaf springs are 1/2" or thicker versus the barstock I buy that is around 3/16" lol

Thank you for being cordial though. Not trying to mislead anybody!

5160 does require more force to forge than simple carbon steels like 1095, it’s because of the chrome content.

Hoss

 

[scott.livesey]

The industry has found that these items when forged to shape are stronger.

Industry forges because it is the cheapest way to make high volume precision parts.
The company I worked for made 12-13 million forgings per year that became drive axle assemblies for Toyota, Ford and Honda. We also made small ones for Polaris 4 wheelers and big ones for Hummer. We did warm forming(1800*F), shot blast, then cold form(room temperature). cold form parts had tolerances in some dimensions as low as +/-0.025mm. these areas needed no further machining and were just washed and lubed before final assembly. Steel used was 1045 or 1050S depending on customer. Again, the process is for high volume precision parts.
the old sailor

 

[AVigil]

"Ok, I will bite.

How much stronger is a forged blade over a stock removal blade of the same design?

All evidence welcome."

Bueller, Bueller, Bueller

 

[samuraistuart]

Isn’t strength directly related to hardness? And if that’s the case, obviously a forged blade isn’t going to be harder after the quench than a stock removal blade, all things equal.

Toughness, however, is a different property than strength. And as I understand it, if a blade was made from stock removal in the rolling direction (as opposed to across it), then I would think there would also be no difference in a forged blade vs stock removal blade.

Especially with a high alloy steel like D2, forging offers more opportunities to mess things up than stock removal.

 

[Willie71]

Isn’t strength directly related to hardness? And if that’s the case, obviously a forged blade isn’t going to be harder after the quench than a stock removal blade, all things equal.

Toughness, however, is a different property than strength. And as I understand it, if a blade was made from stock removal in the rolling direction (as opposed to across it), then I would think there would also be no difference in a forged blade vs stock removal blade.

Especially with a high alloy steel like D2, forging offers more opportunities to mess things up than stock removal.

Best I can tell, a drop forged blade might offer an incremental increase in toughness, but the difference will be so small, it would not be detectibke. Crankshafts are a totally different animal. Different loads, different needs, and the forging is basically the same as rolling a complex shape. Our steel is forged roughly into shape by rolling it into a sheet.

 

[AVigil]

I guess this is why this keeps coming up and people go round and round.

If a forged blade is claimed to be stronger, then a ground blade of the same dimensions, and no one has any evidence for this claim it defaults to "unproven claim"

 

[scott.livesey]

We should realize that most non-cpm tool steels have been forged, then hot rolled, then cold rolled, then possibly ground(PGFS) before we buy them. Stock removal is basically shaping a forged steel blank.
I take a piece of ISO certified precision ground flat stock, shape it creating minimal heat, then heat it to hardening temperature once before quenching and tempering.
You take a the same piece of steel, shape it while heating it above hardening temperature many times, then heat it several more times before quenching and tempering.
Who has the most chance for error?
the old sailor

 

[Willie71]

We should realize that most non-cpm tool steels have been forged, then hot rolled, then cold rolled, then possibly ground(PGFS) before we buy them. Stock removal is basically shaping a forged steel blank.
I take a piece of ISO certified precision ground flat stock, shape it creating minimal heat, then heat it to hardening temperature once before quenching and tempering.
You take a the same piece of steel, shape it while heating it above hardening temperature many times, then heat it several more times before quenching and tempering.
Who has the most chance for error?
the old sailor

Even cpm steels are rolled to thickness.