Spring fabrication

[DrDucati]

I had good luck in the past with Brownells spring steel, which is listed as 1095 cold rolled.
But, the sizes they have are not big enough for the mainspring I am making so I got a piece from a company online, 1095.

After shaping, I hardened it though even getting it orange it did not cease to be magnetic. I tempered it to a blue with torch and installed it.

The result is that it deforms some and becomes a loose fit. I repeated the process with the same result. Then I realized that it was still functioning as a spring with repeatability, just not with the curvature needed to do the job properly.

First I thought it was a failure to harden. But later I decided that maybe it just "set" at a point I don't want. If it were too soft I would think it wouldn't continue to function at all.

Maybe I have to anneal it, bend it beyond the curve needed, and heat treat it again so it will set where I need it when it's flexed the first time.

Any opinion of whether I'm on the right track, or is this just wishful thinking?

[john.k]

if you still have some,harden it same way as you did,and see if it will snap,and look at the grain.......it may be an alloy steel ,and will need around 850C to harden,or it may not harden at all.If it hardens ok,temper it in melted lead in your pot.......melted lead with some solid lead in the melt is going to be right on temp.for a 1090 spring.

[DrDucati]

What am I looking for in the appearance of the grain?

[DrDucati]

Using two MAP torches I was able to get the part to lose magnetism and it's annealing in a fire brick, vermiculite box. Then I will try the cycle again.

I notice that Brownells states their spring steel is 1075 but the customer service rep answered the online questions from customers by stating it's 1095.

[john.k]

1095 would be closer to traditional spring ......higher carbon lowers critical temperature slightly........the catch with torch heating,is that the steel needs to soak at the temp for at least 5 minutes,and with a torch its hard to avoid decarburizing the surface......you will still have a spring,but only part of the steel will be a proper spring,the soft surface part will deaden the spring action.....Lead can be heated hot enough to harden spring steel,but there is a risk of lead vapour,which is a dangerous poison.....there is no risk at 320 deg C.

[429421Cowboy]

In addition to the suggestions given, maybe a few normalizing cycles before quenching and tempering could help? Or do the temper in an oven after a vegetable oil quench to allow the part to soak at tempering temp for awhile?

[DrDucati]

Brownells clarified for me that their spring steel is actually 1075. I will try another vendor's annealed 1075 out, as 1075 worked alright for
a lever spring on my win 76. If that does not pan out, I am considering the purchase of a tiny-capacity heat treat oven.