Heat Treating - Can someone help me understand what Murray Carter is doing?

Willie71 said:
I don't care who you are, no human eye can recognize +/-10f in the 1400-1500f range.
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I'm not saying you can't do a decent heat treat by "magnet and eye" with the right kind of steel... but I'm willing to bet that the human eye is lucky to get +/- 100F at any given temperature. Having said that, the human eye CAN pick up on decalescence, which is the best physical evidence of transformation. T/Cs, pyrometers and kilns can be out of calibration... decalescence is the only truth!
 
DevinT said:
All of the knives I tested and owned were made by Japanese or Japanese trained smiths.

These steels are designed to respond quickly to thermal cycling. They are made to move from forging to normalizing to annealing to quenching to tempering quickly. Murray Carter has a vidio that shows him making a knife in less than 30 minutes. He forge welds the core, forges out the blade, normalizes, anneals, hardens, tempers, grinds the blade and mounts a pre made handle in less than 30 minutes.

I lived in Japan for two years. I visited every kitchen knife maker, sword maker and custom knife maker I could find. I watched them make knives and not one of them had a complicated heat treatment. I believe that all steels require practice to heat treat properly. That does not make them difficult to heat treat.

Hoss
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Its funny you mention that because if you ever watch vids of cutlery shops like Tojiro, they will make a wheelbarrow full of blades in a day per smith...I actually some one outfit that made a piece of san mai under a 200# hammer that I bet weighed 40 pounds..It was huge, after they made it they just hot cut off hunks and forged each chunk into a blade.. It was actually pretty amazing at how fast they could make a blade..
 
DevinT said:
I lived in Japan for two years. I visited every kitchen knife maker, sword maker and custom knife maker I could find. I watched them make knives and not one of them had a complicated heat treatment. I believe that all steels require practice to heat treat properly. That does not make them difficult to heat treat.
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Although heat treating by eye in a charcoal forge is more common, PLENTY of makers over here heat treat in molten lead baths. And the makers that I have met who heat treat by eye give the steels a soak for five minutes + at constant temp (or do their best to). And of course they should -- hypereutectoids need to soak at temperature. This is why it is common knowledge here that new makers without heat control shouldn't work with a steel like 1095.

Trying to soak a steel at exactly 1450 F for five minutes by eye... well, I'm not going to say that it's absolutely impossible, but it certainly is for me. The really good makers here seem to do a decent job with it, but there's no way they're doing an optimal heat treatment even most of the time. Nevertheless, consumers are happy with the product, so I'm not saying it's an awful HT. But it probably could be better.

My initial point about the relative difficulty of heat treating these steels was because you were implying the steels were formulated specifically for ease of HT by eye, and that's not true. The exception is White #3 with .85% carbon or so. That one was made to be easy, as far as I can tell. And it is. I've made some very nice knives with it before getting my kiln.
 
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There's a lot more to heat treating than just austenitizing. I never said by eye either. I do mean that these simple steels respond well to simple heat treatments.

I am aware of makers using lead bath to austenitize in, blades heat up very quickly in these which promotes small grain size in these steels.

Hoss
 
DevinT said:
There's a lot more to heat treating than just austenitizing. I never said by eye either. I do mean that these simple steels respond well to simple heat treatments.
Hoss
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Yeah, it's true. They definitely don't require extensive annealing or lots of thermal cycling. In my limited testing, I've found that the grain size in the quenched steel is the same regardless of whether I just normalize at 1550 F and then go to my austentize + quench vs doing a lots of thermal cycling in between. What does seem to make an enormous difference in the grain size is whether my final quenching temp is 1430 vs 1475...
 
DevinT said:
Sounds simple to me.

Hoss
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I think we have been operating under different definitions of simple. Simple for someone with precise heat control? You bet. And that goes for a great many of the blade steels we all work with.

Does that mean these steels were formulated for easy HT at the cost of performance? No.
 
You are not going to give up on this. I never said that you give up performance. You are defending things that are not there.

There is a whole world of alloys and heat treating out there. Lots of makers are chasing the holy grail of steel and heat treatment. The Japanese are smart to stick with one or two alloys and optimize the heat treat.

Hoss
 
DevinT said:
Lots of common steels are better than white or blue steel. These alloys are made for easy heat treating. They are adequate for most cutlery applications, but not superior. I don't understand all the hype.

Hoss
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Apologies if I misinterpreted your statement here. It sounds to me like you're saying that they were made for easy heat treating. If the performance is adequate, then they weren't formulated for performance.





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HSC /// said:
alot going on here so forgive me if I missed it. In your opinion, why were these steels formulated?
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They're cutlery steels, so I should think they were designed for knives with the properties desired. For white, keenness of the edge and sharpenability are where it excels. For blue, better edge retention and edge stability at high hardness and thin edges. (This is how I see it anyway; I'm not a metallurgist at Hitachi)


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Is it your opinion that white and blue steels by hitachi are the ultimate kitchen knife steels?

Hoss
 
DevinT said:
Is it your opinion that white and blue steels by hitachi are the ultimate kitchen knife steels?

Hoss
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Of course not. Now we really are going around in circles. A white steel knife might be just what a chef is looking for if they don't mind touching it up relatively often to maintain a screaming sharp edge. It's a nice, simple carbon (probably holds its edge a bit longer than 1095).

As for the blue steels, I would say they're as good as any of the top rate kitchen knife steels for edge stability on thin knives. So certainly among the best steels to choose if you're making a chef knife, in the league of 52100, etc.



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I have had multiple white and blue steel knive and always preferred my Konosuke HD2 knife which uses a proprietary semi stainless tool steel. That is until I got my Gihei blue #2. Whatever he did during the heat treat is insane. He says its taken up to 62-64 hrc but it outshines every knife I've had in edge retention and takes an edge almost like it was white #1. That said this shop normally uses ZDP 189 and HAP40 so I highly doubt he is heat treating by eye
It's just too perfect.
Only steel I've ever heat treated myself was 14c28n and I used an evenheat and air quenched in aluminum blocks. Takes a really fine edge, great stuff. Would make a great kitchen knife with how easy it sharpens.
 
HSC /// said:
this thread has certainly lost it's focus from the OP :-)
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But it's been an interesting diversion.

Willie71 said:
Not to start a flame war on heat treat methods, but Jim said it earlier. Traditional smiths make good knives in spite of their methods, not because of them. Traditional smiths are selling an image, a mystique.
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My interest is because these techniques look straightforward enough that I can imagine being able to pull them off without gearing up well beyond what I'm willing to invest (and have the space to store).

I have a generalized desire to make kitchen knives (plus the occasional utility and hunter) and am attracted to the San Mai look, especially in some of the more extreme examples (http://www.bladeforums.com/forums/showthread.php/1356195-San-Mai-varieties).

The clay wash was interesting to me because I do not have a welder, and I thought the clay wash might be a way to mitigate the scale problems during forge welding (when I cannot seal up a billet via "regular" welding). That isn't what Murray was doing, he was using the clay during HT, but I was wondering about borrowing that technique.

The HT is interesting to me simply because his blade isn't delaminating, plus I am going to be attempting to HT some 1095 without the benefit of proper HT oil - it looked like Murrary's technique made this work, although best for laminated blades.

The cold forging was interesting simply because I can't believe those blades aren't shattering.

The spheroidal annealing information was super informative.

Thanks again to everyone for contributing to this thread.
 
Steve98 said:
But it's been an interesting diversion.



My interest is because these techniques look straightforward enough that I can imagine being able to pull them off without gearing up well beyond what I'm willing to invest (and have the space to store).

I have a generalized desire to make kitchen knives (plus the occasional utility and hunter) and am attracted to the San Mai look, especially in some of the more extreme examples (http://www.bladeforums.com/forums/showthread.php/1356195-San-Mai-varieties).

The clay wash was interesting to me because I do not have a welder, and I thought the clay wash might be a way to mitigate the scale problems during forge welding (when I cannot seal up a billet via "regular" welding). That isn't what Murray was doing, he was using the clay during HT, but I was wondering about borrowing that technique.

The HT is interesting to me simply because his blade isn't delaminating, plus I am going to be attempting to HT some 1095 without the benefit of proper HT oil - it looked like Murrary's technique made this work, although best for laminated blades.

The cold forging was interesting simply because I can't believe those blades aren't shattering.

The spheroidal annealing information was super informative.

Thanks again to everyone for contributing to this thread.
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You can make a very good knife out of 1084, 1075, and even 15n20 with just a basic forge and heated canola oil to quench in. No need to gear up a lot to get started. Consistent heat treat by eye with hypereuctoid steels requires a lot of practice and many ruined blades, or underperforming blades, or equipment with good temp control.

I think it would be very interesting to see if Kevin Cashen would be willing to look at these hitachi steels heat treated by eye vs, heat treated using better metallurgical scientific methods. If they are both the same in the end, debate over. I highly doubt they will be the same.
 
Practice,practice and more practice..Thats what it takes to get good at heat treating in a forge. or a muffle and thermocouple:D
 
Kentucky said:
Practice,practice and more practice..Thats what it takes to get good at heat treating in a forge. or a muffle and thermocouple:D
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Practice and a controlled work environment. Light and room temperature for example. My forge and kiln behaved very differently from season to season before I acquired climate control.
 
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