Leaf spring material hardening question

merlin49

merlin49

Joined
Jul 1, 2007
Messages
23
Being a basic cheapskate I hate the idea of not using the scrap that I have laying around to make blades. Keep in mind I do it as a hobby, the blades I have made have been gifts for family.

That said here goes. I took a leaf spring from a school bus, I believe it to be 5160, and cut bars at 1"x3/8x12". Now I did torch cut these which may be part of the problem. I forged the first blade and went to heat treat. I brought it to nonmagnetic and quenched it in hydrolic oil heated to 100 degrees. My good file still cut it. I repeated this twice with the same result. Then in frustration I brought it up again and quenched directly in water. The blade cracked but the file still cuts.

Could it be that flame cutting ruined this steel?
 
I too am curious about this as i'm about to start playing around with leaf springs.

How long did you let the steel stay at nonmagnetic? Would that change any results?
 
I see this over and over. Someone says "I brought it to non-magnetic then quenched". Where did this idea originate? Non-magnetic, 1414° is almost never enough heat for a quench. Most carbon steels require 50°, to 75° higher, with at least a short soak in order to come to any kind of solution. Some steels require a good deal more heat. Most eyes will see this as bright red-orange in very dim light. Your oil needs to be around 125°, to 135° in order to reduce the vapor jacket that will form around the blade. Not all springs are 5160, and could be maybe 1095, or one of at least a few others. 5160 does not go to good solution with less than 8, or 10 minutes soaking at quench temp. Increase your temps on the quench oil, and the steel, and try again, and if your file does not skate, file a little deeper and see. You may have a little decarb on the surface.
 
I let it soak at nonmagnetic for only about a minute or two I was worried about over heating it if I left it longer.
 
Thanks LRB I will try again with higher temps and longer soak. I emailed Navistar because they are IH school bus and trucks for their spring standard but have had no reply yet.
Bob k
 
If it is 5160, the high chrome content will retard grain growth, but it would be wise to thermocycle the blade before quenching, especially if you are going to forge it.
 
Watch the colors of the blade carefully. When the tip or a thin area becomes non magnetic, bring the rest of the blade to the color of the tip when it was non magnetic, then soak for another 2-3 minutes. make sure to watch the thicker areas and wait till there no dark shadows left and it is an even color, then it should be heated through... If your forge is hot enough, after following that routing, the blade should be hot enough to quench.
 
LRB said:
it would be wise to thermocycle the blade before quenching, especially if you are going to forge it.
Click to expand...

How do you thermocycle before quenching?

Would that be heating and allowing to slowly cool several times?
 
For normalizing after forging is 99.9% done, I do two or three heats to a dull red and use those heats to do the final straightening and touch ups and allow to cool to room temp in between, then to one final heat and cool in still air without any straightening. At that point it's ready for the quenching heat.
 
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