Hammerhand
Howdy, I am a geezer with a hammer. Been smithing about 17 years now, I volunteer as a historical interpreter (blacksmith) ar Washington on the Brazos State Historical Park in Washington, Tx. I am a retired metallugical engineer with a lot of experience in the steel industry. I am happy to help with questions.
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jmccustomknives
Awesome to have you!  Looking forward to your input.

Rule #10;  "I can make that" translates to; "I'm to cheap to buy it new."

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Metalmelt
Welcome, I worked in a steel mill for several years and played as a Metallurgist. Learned a lot by trial and error and by reading. We had a pretty narrow range of steels, mostly low to medium carbon.
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Hank Rearden
Thanks, I'll have a few questions soon. I have a few projects on the burners this year. Monkey tools and punches etc. But before I get to them I have some work for others to do first. Thanks for joining and offering your expertise.
code[Maglio.gif]  Keep the fires burning hot!
2020 ABANA Conference in Sarasota New York. June 3rd. through June 6th. Plan now!
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Metalman
Hello Hammerhand - I am sure glad to see you come along.  I have been tinkering for more than 40 years to try getting a handle on something.  I am familiar with the normal metal heat treating process of  'Annealing, working, hardening and tempering'.  But, can you tell me anything about this process...'Annealing, working and then heating up to some lower temperature and then quenching for some desired hardness'?  In other words doing the normal last two steps of the 'Hardening and Tempering' process by just one quenching and hardening step.  Do you know of any acceptable or even 'unacceptable' system or technique for doing this?

It was just the other day that I made some wood checkering tools by 'work hardening some 3/16th steel rods and then filing in the teeth.

Any thoughts, thank you much,

Metalman 


   
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Hammerhand
Metalman, your process would be a real benefit to the industry but unfortunately there is just no such shortcut.  To harden steel, you must heat it above the upper critical temperature to form what is called "Austenite".  Austenite is the parent of all other microstructures and if you do not achieved an austenitic structure, quenching will only cool the metal.  No transformation will take place.  The temperature at which austenite forms is a function of the carbon content.  Up to about .8% C, the higher the carbon, the closer the transformation temperature is to the lower critical temperature.  At about ,8% C, you can achieve a fully austenitic structure at about 1340F.  Above and below .8%C, the temperature gradually increases to about 1650F.  A bit of time at temperature will allow carbides to dissolve and achieve a slightly higher as-quenched hardness, too.  Hope that made sense.  Some diagrams would be helpful but I don't have anything available.
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Metalman
Hi again Hammerhand - Thanks, I have all of the normal diagrams.  I have just tried to think of ways to catch things in the middle of all of those happenings - like maybe just shy of what may be normal.  I am a retired Metrologist - always thinking out of the box.

Best regards,
Metalman  
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Hank Rearden
Here's a question I need to answer.

I have some worn out dull saw blade band from the steel supplier. I believe it has .08 cobalt if I remember correctly. I originally wanted to try to make Damascus out of it. My question s can I forge weld steel with cobalt?

I also have a excavator sized pulverize bit. I think S7.  Is that too tough to hand forge? 
code[Maglio.gif]  Keep the fires burning hot!
2020 ABANA Conference in Sarasota New York. June 3rd. through June 6th. Plan now!
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Hammerhand
Is the saw edge welded on or cut into the band? I think you can weld it but I've never tried it. S7 is harder than woodpecker lips. I have been trying to forge a hammerhead into an adze head but I think it is S7. I have yet to get it how I want it. Good luck.
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jmccustomknives
Cobalt will definitely cause trouble with welding.  It will not weld to itself in my experience, it might with a simple carbon steel in between but I'm not sure.  That all depends on the other alloys. 

As far as S-7, it is forgeable but your arm will be cussin' you in the morning.

Rule #10;  "I can make that" translates to; "I'm to cheap to buy it new."

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Hammerhand
The welding books say cobalt is eadily welded using low heat input. However, there is no data on forge welding of cobalt-containing steels. It can be resistance spot welded which is similar to forge welding. Cobalt has high resistance to oxidation and has high red heat strength. The red heat strength may be the problem in that it does not readily deform to get good surface contact in The weld.
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