Spring steel

[petersenj20]

Is spring steel just high carbon steel? I have seen lots of places that sell all kinds of hardening steel but never spring steel.

Also leaf springs seem to interchange with high carbon applications such as knives.

[RainsFire]

yep, for the most part its just carbon steel that has been tempered to be springy instead of brittle and edge holding. Usually its like 1065 steel, or another alloy. Really pretty decent as a starting blade steel.

[Mike Turner]

Just thought I would add this, I have made springs from wrought iron that has little to no carbon. Also I know a guy that uses wrought iron to make springs for his kentucky style rifles.

[JohnW]

I believe that almost any steel can be used for a spring. BP205 (knife making 101) gives a description of steels and sources, Richard Hanson says that car and truck leaf and coil springs use various steels including 5160, 1095, 1085, and 4360.

[Marc]

All steel pretty much has the same "springy-ness", or spring force. What the spring steels do is allow the spring to be bent further before taking a permanent set. So if your spring doesn't need to travel much, just about anything, including cheap mild steel, will do.

[petersenj20]

A totally different subject but I am thinking of making coil springs for a go-kart. It just occurred to me that leaf springs would be much easier to incorporate. I saw a show once that made a leaf spring for a motorcycle and at the time it shocked me that it was so simple. Of course they never mentioned what kind of steel it was.

The MSC Big Blue Book has some simple info about their hardenable steels but very informative. Especially at good prices. I just have never seen metal advertised as spring steel. This is why old books are so wonderful to have. I have a backwoodsman magazine that shows how to make springs for a gun reproduction. Again it didn't mention the type of steel as I recall.

To make a spring would you harden and then draw to a higher temp than for a knife, or just use a high temperature draw?
And one more thing. What exactly is wrought iron? I read somewhere that it doesn't really exist any longer. From lots of time on this site this is obviously not true, but I have been reluctant to ask.

[Candidquality]

Can't help on the spring but the wrought looks like this

It hasn't been made in the us since 1907 and the last plant in Europe shut down in 1972 or so. There's a place that recycles it now and rolls it into new stock overseas. But no actual new production.

Notice in the picture that it appears to have a wood like grain when broken. this is due to inclusions of silica slag(about 5 percent) in almost pure iron. Carbon content is below .03% or so. Works at a white heat and moves like butter, easy to forge weld (probably due to slag content making it self fluxing). Wonderful stuff. Pretty sure we've got a blueprint with a decent amount of information on it.

edit: click on the picture that pulls up in the gallery for an extremely large closeup.
edit 2: found the blueprint http://www.iforgeiron.com/blueprints-100-200/bp0104-wrought-iron.html

[Jmercier]

"spring steel" is basically any tool steel used to make springs, the most common in the automotive industry today is 5160.

wrought iron as smiths define it is a material no longer produced, but still available by recycling older pieces of wrought iron. It's an iron that used to be produced in bloomeries and other long refining processes, and is known for it's high inclusion of slag and impurities and it's negligible carbon content. At high temperatures the amount of silicon in wrought iron essentially makes it self-fluxing, but if you work it at low temperatures the high number of impurities cause it to crumble and become useless. Wrought iron has been entierly replaced by mild steel in modern commercial processes.

[JohnW]

petersenj20, as for the tempering, there's a thread titled "spring treatment" with some discussion. Just click on Search and enter "spring temper", it will be about the 15th one in the list. Heck, it might be the 1st on the list, if you put in "spring treatment".

[ThomasPowers]

Wrought Iron was the metal of the blacksmith from the beginning of the iron age until after the American Civil War when the Bessemer process made cheaper "mild steel" available.

It was still in declining use in the 1880's-1890's as "PracticalBlacksmithing", Richardson, has a bit of discussion between smiths on how to work the "new" material---especially WRT welding the new steels.

The Great Depression of the 1930's put the end to most of it's use; though it was still spec'd for areas of high corrosion into the 1950's in America.

So if you are doing any replica work of ACW or before you should be using it if you are trying to "do it right". Since it can have an interesting wood grain pattern when etched many people like to use it for knife furniture.

Wrought Iron used to be processed into steel using the blister steel process where it was soaked in carbon containing chests at high heats for long periods---red hot for 10 days for example, leaving the surface covered in little pimples ("blisters"). This would then be stacked and welded and drawn back out to give you "shear steel". You could also send it through the soaking again giving double blistered steel for things like razors that very high C was wanted for. You could also stack and weld shear steel to get double shear steel with a more even carbon content and if you really had money to burn: double blistered double shear steel.

Blister steel could also be melted in a crucible to make cast steel aka crucible steel that would have a much more even carbon content and not have any silicate stringers left from the original WI; in the West Crucible steel was a 18th century invention. In the east the wootz steels and other crucible steels had been known in early medieval times.

[Mike Turner]

Thomas Great explanation I could not have done it that well myself :cool:. With wrought iron since it lacks carbon for for hardening what I have done is work harden it to get the desired spring tension I needed. Wrought is very hard to find if you come across it never pass up the chance to get it, even if you don't want to use it others will gladly buy it from you. I only brought up wrought iron to get you thinking out of the box because we can also go clear to the other side, I know guys that use high carbon stainless steels as springs for slipjoint folders. It really depends on the use of the spring as to what steel I would use and your heat treat and temper are the most important factors in the performance of your spring IMHO.;)