How to harden

This is why I love this site. george thank you for the great input. I don't mean to single out only george. I just read a couple other threads and the input from the members here is wonderful. Thanks
 
Thanks George. That was what I was looking for. Had never heard of the steel wool trick but I can see its use and will give it a try. Most of the time I order W1 for everything I do that needs hardening but think I will try some O1 next time to see how it turns out.

Jeff
 
churchw: If you look up the chemistry of 01 and W1,you will see that 01 has alloys in it that make it a better metal from the standpoint of wear resistance,less risky to harden without distortion or cracking,warping,etc.. It,as I have stated,will not QUITE take as razor sharp an edge as W1(but only a TRIFLE less sharp),but it will hold it longer.

W1 is also getting harder to buy,as steel makers are not making it so much any more.

I use cold drawn W1 for letter and number stamps because it is cheaper,but if I heat to hardening heat a 2" long,1/4" letter stamp for its full length,it invariably splits a crack right up the center of the stamp. So,I heat up only the business end of the stamp. This shows how treacherous W1 is in hardening. 01,you can heat all over.

If I want to make a knife blade that will take the keenest possible edge(for steel,obsidian will chip much sharper,because the edge fractures down to 1 molecule thick) I'll use W1. But,I know it will not stay sharp as long.

As an example,I had to skive some ray (also called Shagreen) skin which was chrome tanned,and was very rubbery. I could not get this rare skin in vegetable tanned. I could only get a W1 blade to cut it well. an 01 blade just didn't get quite keen enough. So,there are applications where you might like to use W1.
 
I might mention why you should use a brine quench: It is because in plain water,a gas envelope forms around red hot steel when it is plunged into the quench. This can cause uneven cooling of the steel,enhancing the opportunity for uneven hardening,warping,cracking,and other problems to occur.

Brine prevents this gas envelope from forming. I will warn you to clean your quenched parts thoroughly to prevent rusting. Quenching in brine will rust your tongs severely,too. They rust even if you rinse them under the faucet after quenching. The tongs I used for quenching were already brown with a surface typical of blacksmith's tongs when I started using them. This rust most likely gave a place for the salt to sink into. The parts I quenched were not rusty,though,and did not rust after I thoroughly rinsed and dried them.
 
Lone Watie said:
I keep reading about hardening stock and hoping for some guidance on 'painless' ways to do so. Any takers on this? Thanks.
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The members have given you a lot of good at home hobby tips.

I want to make some slotter tooling that is no longer available so I also have the same interest you do. I just last night finished a good "bedside read" (put me to sleep several nights). It is an old ref. book that discusses steel and its treatments. It defines terms used to describe steel strength and hardness properties and how they are arrived at. It also gives some examples of material properties and how they are important to various components many of these are car parts that we can relate to. The methods described in the book are mainly industry ones but can be achieved at home as the members have noted. The online copy is free and located at:

http://books.google.com/books/about/Steel_and_its_treatment.html?id=SvRZAAAAYAAJ

Have fun with the hobby!

Benny
 
HSS will decarburize if heated in the presence of air,and a thick soft skin will be formed on it. It takes special equipment to harden HSS properly,and it quenches in AIR,not oil. You are lucky it didn't crack.

As far as mere hardness is concerned,W1 plain carbon steel will get harder than just about any steel(I'm leaving out CMP powdered steel,which I haven't used,and don't know about) W1 will reach 67 R.C.. The HSS's I have tested with the Versitron hardness tester(a very good machine),only showed about 63 R.C. hardness. Of course,HSS ready to use has already been tempered at about 1000º to add some toughness.

The very high tempering temperature of HSS is why it can cut steel at high speed,and get very hot without losing its edge. "Red hot and still sharp" was an old ad for some brand of HSS. It was shown being heated with an acetylene torch red hot,while in a lathe cutting metal.

At 67 R.C. the W1 won't have any toughness,either,and will be quite brittle. Hardness isn't the only desirable factor. You must have some toughness as well,which is gotten by sacrificing some hardness,or you will be trying to use glass to cut with,essentially.
 
TLGriff said:
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A trick I use with O1 is to burn the oil off with a torch after quenching. When the oil just stops smoking, the part will be around 450F. That also gives the part a nice black finish.

Tom
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Great idea, Tom. I'll give it a try. Just today made a 1 1/4" dia., 3/16" thick, 12-tooth cutting wheel out of O-1. After a bit of cleanup with jeweler's files, etc., I'll harden and temper it. BTW, I'm using olive oil as the quench, which I presume doesn't matter for the hardening step. But I wonder if the smoke stops when tempering at 450ºF. What kind of oil do you use?

Mike
 
Well,you could just grind off the soft skin. Actually,after reading this last post,we made some of those old fashioned boring bars from HSS,too. We heated them up red hot for forging them,but did not quench them in oil. Just air cooled. They got plenty hard from just red hot temp.,and we ground off the soft skin where the cutting edge was.

I think lots of old shops did that too. Not proper,as you say,but good enough to make functional tools,though not as good as properly heat treated HSS would have been.
 
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