Looking for history of 5160 spring steel

[Chris Evans]

Originally Posted by Ian

. It's main commercial use has been in the manufacture of leaf suspension springs for automobiles and trucks. In some parts of the world, such as the Philippines, these leaf springs are scavenged from old vehicles and the steel is forged into edged tools and weapons.

Ian,

Leaf springs have been made from a variety of steels, not just 5160. Over the years I have seen mentioned 9260, L6 and the higher carbon content 10xx series including 1095.

So we must not make the assumption that just because many leaf springs were made from 5160, that all were of the same material.

As an aside, making swords and knives from discarded used leaf springs is not a very good idea because these springs develop micro fatigue cracks that are an invitation for later breakage in a sword of knife.

As another aside, the village blacksmiths in SE Asia tend to only harden the edges with a shallow edge quench and leave the rest of the blade soft, which mitigates the above risk, though it would not work all that well with thin bladed swords, at least not to our expectations.

Cheers
Chris

[Ian]

Originally Posted by Chris Evans

Ian,

Leaf springs have been made from a variety of steels, not just 5160. Over the years I have seen mentioned 9260, L6 and the higher carbon content 10xx series including 1095.

So we must not make the assumption that just because many leaf springs were made from 5160, that all were of the same material. ...

Very true. I am reading now some of the other materials used for leaf springs and will report back shortly.

... As an aside, making swords and knives from discarded used leaf springs is not a very good idea because these springs develop micro fatigue cracks that are an invitation for later breakage in a sword of knife. ...

Chris, would not some of these mirco-cracks be corrected during the forging process? The bar stock provided by a leaf would need to be worked extensively on the forge to get to a knife or sword blade.

... As another aside, the village blacksmiths in SE Asia tend to only harden the edges with a shallow edge quench and leave the rest of the blade soft, which mitigates the above risk, though it would not work all that well with thin bladed swords, at least not to our expectations. ...

Chris, I agree, but I don't think there are a lot of thin-bladed weapons or tools made from these sources. What I have seen are nearly all fairly sturdy pieces that are designed to last a long time. I know people who have had the same bolo for 20+ years and used it regularly.

[Chris Evans]

Originally Posted by Ian

Chris, would not some of these mirco-cracks be corrected during the forging process?

Maybe, but chances are against it. The inside surfaces of the crack become oxidized and are unlikely to weld shut, unless a flux is introduced.

The practice of recycling used leaf springs is not best practice because for starters one does not know the steel's composition and thus the heat treatment cannot be optimized. And then there's the matter of the said fatigue cracks.

In summary, it is one of those things that is widely done in the poorer regions of the world with the assumotion that near enough is good enough and things are OK until they are not.

This subject has been discussed over and over on blade smith forums and the experts always prefer new steel of a known composition. After all, plain and low alloy carbon steels are quite cheap.

Cheers
Chris