Spring steel problems

Southclaw

Southclaw

Joined
Nov 30, 2009
Messages
157
Hello I am new to the forum. I just signed up yesterday. I am also new to making knives. I have made a total of five completed knives so far. I have been looking around and can’t find an answer to a question that I have. I was making three knives at the same time out of a leaf spring from a 68 ford bronco. When I hardened them I only was able to keep one. The other two bend to the side. I tried to normalize them and re harden them but they did it again. They also have curved cracks on the side of the knife. I was wondering if it has anything to do with the knives being made out of old spring steel? If so, is there any way to avoid this in the future? Or is there a way to check the steel before I start to forge it into a knife?
Oh if you need to know, they were water quenched. I would like to get into oil but I do not have that set up yet.
 
Because it was free. Lol And I wanted to make some more knives to be sure that when I buy steel the knife will turn out good. The test blade I made out of the spring worked pretty good.
 
Several things come to mind. One, did you normalize thoroughly, three good cycles at decreasing temperatures, before you heat treated them? Two, do you know how hot they were when you put them into the quench? Sometimes overheating leads to more cracking and or warping. Three, sometimes with water, that's just what you get. Try warm vet grade mineral or canola oil and see what happens.

There are some folks on here that will throw crap for you wanting to use a leaf spring vs. some new 1084. There are good reasons why they do that, but there are other good reasons to use a leaf spring. You can say, "I made this knife from the leaf spring off of my grandpa's 68 Ford," while they can only say, "I made this knife out of some bar stock I bought on the internet." They might can nail the heat treat, where you're only likely to get close, but your knife will still have value to you and to a potential customer.
 
I did normalize them. I am not sure I did it right. I am learning a lot by trial and error. I do not know anyone by me that I can go to there shop and learn from first hand. I heated them till they were nonmagnetic and quenched them.
The main reason that I am using spring steel is that I am really tight on cash at the moment. When I am more secure with my knife making abilities I will be buying some steel. Is 1084 the best steel to start with? After spring steel of course. Lol
 
Nothing wrong with the leaf springs, you just need to learn to work it.

Like said, normalize, don't overheat, warm up your water, interupted quench, oil, etc.
 
Don. "interupted quench" ? Sorry I am still learning. What would be overheated? I use a gas forge that I made. it takes a bit for me to get it to the point where it is nonmagnetic.

Ryan. I am in Amherst,WI
 
You want the temp slightly above non-magnetic. You also need a very even heat.

Interupted quench; in the water for two or three seconds, then out for 2 or 3, then back in.
 
Thank you Don. Is there a thread that you can refer me to for the advantages of interrupted quench, and what it does for steel? I hate to have you repeating something you have said many times.
 
Southclaw,
First, welcome.
Second, if you fill out your profile you will be more likely to have a bladesmith who lives in your area chime in with "Hey you're only a couple of miles from where I live, c'mon over"

third, read the "newbies good info here" stickies and Kevin's stickies on working with the various steels.

Using old leaf springs will cause you to have more problems than working with new known steel.
Quenching in water will give you a very uneven quench and put a lot of stress on the blade unnecessarily. olive or canola oil heated to 130 f will give you a good even quench without the vapor jacket issues of water. Quench point or edge first, and don't lay your blades in the forge on their side for HT. I went to someone's shop and they asked me why their blades were always bending in HT, it turned out they were laying on their side in the forge during HT

-Page
 
SC, I don't know of any threads without searching. A interrupted quench will minimize cracking and warping when one uses water. It's not necessary when using an oil quench. Spring steel is not the best choice for water.
 
Thank you guys. All of your input is much appreciated.
When I switched to leaf springs from files I tried to use transmission oil, but it didn’t seem to cool it fast enough. It would not pass the file test after quenching. I need to make a quench tank for oil, so that I have enough oil in the quench and I have space to pull it through. I do try to get an even heat when I have it in the forge. I probably need to redesign the forge, now that I know what I am doing a little bit more.

Thought I did fill out my profile. I will have to check again.
 
what temp was the transmission oil? a couple of the first blades I made were leaf spring from a '60's ford and would skate a file when I quenched them in 40F motor oil. Up to a point, the oil will get faster when warmer, up to around 140F max. How are you judging temps of the steel? Going to non magnetic is not enough, though you can use the non magnetic point of the blade edge to help judge the colors and then if you watch closely, you will see what's called decalescence; When everything in the steel can no longer hold any more heat in it's current form it will transform and you will see a dark shadow move across the blade, after that happens, it is time to quench.
 
I think the oil was around 180 to 190. I have a thermometer gun but it only goes to 1000f. I judge the temp on the blade by look and magnet. I never heard about the dark shadow. I will have to watch for that.

So I guess I did not have the blade hot enough and the oil was too hot. Lol
Thank you 69_knives. Bladeforums.com Rocks!
 
I wish when I started that somebody would have explained what I was seeing; all I knew was wait for the dark shadows to disappear. It wasn't until 6 or so months into my knifemaking that I actually heard the word decalescense.

Hopefully you forge in enough subdued light that you will be able to see it. When I clamp blades up after the normalize heat I almost always see black shadows ripple through the blade. the ripples usually start at the edge and go in toward the center of the blade. It takes maybe 3 - 4 seconds per ripple.

What this indicates is that the steel has transformed to Austenite, and austenite is what transforms into Martensite when quenched. Martensite is the good, hard stuff we want on the edge of our knives. :)
 
69_Knives
When I am going to harden a blade I turn of the lights so that I can see the colors.
 
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