metallurgy Q

so if i wanted to make a piece of steel "more like" spring steel, would it be good to get it really hot then water quench it? i know that makes it harder, too hard would snap, but if i didn't get it super hot then quenched maybe? i want to make a seat mount similar to those on big lawnmowers where its just a big flat piece of metal bent in a U. or if i wanted to make my own coil springs for seat junk. take some home depot metal, is it wire or rod? what determines this? size? bend it like how i want, heat and dunk? not trying for perfection, just trying to push it in the right direction a little. all idears welcome...

Re: metallurgy Q

Pushrod Fifty /

Spring steel has special alloys in it that lets it bend a bunch of times without breaking. Hardening of steel by quenching is done by heating cherry red and quenching in oil. After it has cooled to room temp in the oil, it is annealed to soften to a hardness that matches the intended use- cleaned and heated until dull gray then quenched again.

The steel has to have a high carbon content to heat treat it. Home depot steel is probably low carbon steel. The galvanised flat brackets and plates that are drilled are heat treated structural pieces that would work for seat brackets and such. If you want to make a custom springy part, salvage a springy one tractor seat bracket and saw cut to shape. It will be hard to work the metal because it is semi hardened. Using a cutoff blade will anneal the metal and return it to soft metal.

Re: metallurgy Q

It’s very difficult to make a consistent spring. You need same uniform heat treat, consistent twist and an even sliding rate.

This all has to happen while working with yellow-orange metal. You also would need to normalize the steel before starting any of it, then re-quench.

You’d also likely be quenching in oil if it’s a high carbon steel.

I’m a part time blacksmith and I would not bother. Way too much work and trouble even with the right tools.

Re: metallurgy Q

♣Slew Foot♣ /

Special process to make spring steel

We have multiple forges around only one makes springs.

Re: metallurgy Q

Pushrod Fifty /

Check out an old Vespa scooter seat, they have a spring in the mount and bolts to a flat surface.

Re: metallurgy Q

mcmaster has a buncha spring steel, there are different grades affecting how springy. If you wanna make yer own you can, the above discouragements are fair cuz it requires a lotta precision to get it repeatably good, but I bet you can wing it and get sorta close to good enough. Probably biggest risk is your homemade springs will fatigue and just crack after a while but it should still work for a while, maybe a long while.

I think you want medium or high carbon, so starting steel matters.the metallurgy of the starting material just affects how easy it is to manage the balacnce of heat treatments and the total strength, toughness, hardness achievable.

1st You need to harden it by getting it hot as fuck. hotter than a 2 dollar pistol. (temp depends on the material but typically ~750C so basically red or even orange should get it)

2nd then quench it fast. doesnt need to be in oil but it's better. You can even quench in like saltwater and surfactants like soap (dishsoap, simple green), basically the goal's just to keep the steam from forming too fast and making so many bubbles that the water can't quench, salt and soap limit that by changing boiling point and surface tension etc. that's also the advantage in oil, you dont have that boiling vapor bubble restricting heat transfer.

3rd, reheat it to not glowing but almost.

if part 1 isn't hot enough, it's gonna deform and flatten out over time

if part 2 isnt fast enough, it's gonna be brittle and crack or fatigue too fast (like a paperclip bending it til it snaps)

and if part 3 isnt hot enough, same issue, its gonna crack or fatigue

If you wanna get technical

1st step is to you harden it or it's too malleable, like it'll jsut flatten out. you need elastic deformation not plastic deformation, it needs to sproing back after it deforms instead of permanently bending. so you harden it by heating and quenching. Basically what you're doing is taking ferrite in typical steel, heating it til it undergoes a phase change to austenite. Austenite's a high temperature atomic arrangement for steel and able to absorb more carbon (which hardens steel) and then you need to cool it super fast (quench) to lock it in, otherwise the carbon disolves back out as it cools.

you can consider "the nose" on a time temperature diagram for steels like this

what you're looking for is a cooling rate that goes from a temp on the Y axis and cools at a rate like the red line, over an amount of time for the X axis. It tells you how fast you gotta quench for it to work. Alot of times you cant cool that fast in just water, especially for thick pieces and that's where you gotta use oil. Alotta time leaf springs are a buncha thinner leafs instead of a big piece partly to slide over each other but also just cuz it's real hard to quench thicker stuff evenly.

Then once it's hard, it's also too brittle which is like exactly what you don't want for springs. it doesnt bend and flatten out permanently anymore, but now it doesnt bend at all, so you gotta temper it. tempering increases toughness, or how much it can bend before it breaks. springs temper at high temperatures. to temper you gotta get it hot but not so hot you go back to austenite. you're instead just redistributing carbides and annealing out stresses and stuff. dont go back to glowing but it's gotta get hot. how hot? usually you can see temper in the color:

spring you wanna go blue to gray like 650F. If you try to anneal in your oven or something it you're maxed probably like 450 and that's gonna still be too brittle and hard.

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