Spring Fuller Failure

[Mark Wargo New2bs]

This was my first attempt at a spring fuller. It was forged from the coil spring off of a jeep. Is this spectacularly large grain structure? I failed to normalize it prior to quenching it in oil (mostly canola). I only tempered it for one cycle of about 90 minutes at a bit over 500 degrees. Do you think the failure was due to failure to normalize, tempering temperature, only one temper cycle, something I'm not considering, or a combination of all the above? Today I forged a 2nd spring fuller and did my best to normalize it correctly. I took it above nonmagnetic, then just above nonmagnetic, then just below nonmagnetic and buried it in ashes. Should this help reduce grain size appropriately? Any help is greatly appreciated.

Mark

[Ed Steinkirchner]

you dont need to temper the spring part on a spring fuller, not even the fuller part really. i would harden the dies after triple normalizing(heat to non mag and let air-cool) then temper to bronze-purple,or softer than my hammer and anvil face, whichever. no matter the temper, it will hold up for a long time. i have one from an old crowbar, no heat treat except for 2 normalizing cycles, hasnt turned swayback yet and wont hurt may anvil or hammer.
by the way, it looks like it was either too hot in hardening, of the quenchant was too severe. is the break in the fuller part or the spring?

Ed Steinkirchner

[Mark Wargo New2bs]

It broke in the spring section. I was hammering and doing fine, the next thing I know, the top of the fuller is flying by on its way to the floor. So, after normalizing the one I forged today, use it as is rather than quench and temper?

Mark

[Ed Steinkirchner]

i would heat treat just the fuller area and leave the spring normalized, because it is not going to do anything more than hold them in line really. how thick is he flat section and did you weld a hardy post on it?

Ed Steinkirchner

[Steve Shimanek]

Mild steel is sufficient for spring fullers, so an actual spring is overkill and may complicate your life unnecessarily at this point.

[ThomasPowers]

Burying in ashes from Critical temp is an anneal. What are you trying to do? Critical to room temp in still air is normalization.

[MattBower]

To answer the original question, yeah, that's big, nasty grain. Below is a pic of the end of a freshly hardened and broken piece of high carbon steel. The satiny part -- everything but the part right near the edge -- shows pretty good grain. You can see where it got a tad hot at the edge, and the grain started to grow. Not good. That may be why it cracked in the quench, and thus became available to be photographed. (By the way, that's a penny in the foreground for scale.)

[Mark Wargo New2bs]

I was trying to reduce the grain size so that the spring fuller wouldn't break during use. I allowed it to air cool for the first two heats, then heated to below critical and buried in ashes. I honestly got that by watching a Youtube video of a blacksmith from canada thermal cycling coil springs mae into chisels prior to quenching, though he buried his in vermiculite. He heated to medium orange and air cooled, then dark orange and air cooled, then red and buried.

[MattBower]

The red and buried part is likely what did you in. Normalizing typically employs air cooling. Grain growth is a fuction of time and temperature. If you bury a hot piece of steel in vermiculite, it'll stay hot for a long time. If it's hot enough when you bury it, grain growth will continue for a portion of that time. Normally I'd say red isn't hot enough to form austenite and cause grain growth, but I guess that depends a lot on your calibrated eyeball and the lighting in your smithy.

[Mark Wargo New2bs]

This is the link to the video I was referring to earlier regarding burying the piece during thermal cycling. I'm reading that the consensus is that it shouldn't be done, but rather allow it to air cool that final time as well. Does it need to cool to ambient temperature each time or is a few minutes after it loses all color acceptable?

Thermal Cycling

Mark

[viking-sword]

Though I have not seen the video, I can tell you that your process's are a little confused. When you normalize, you should bring the metal up to just below the critical temp(non magnetic), this will be a good red color and not at all orange, which you did twice, this is what grew your grain to an enormous size, and when you anneal, you should bring it to just above the critical temp(again non magnetic) and then put it in the medium you have for slow cooling. In thermal cycling you should never see an orange color unless your using some types of tool steel, orange is bad, very bad, grows grain, grows lots of grain! Don't depend on eye judgement if you don't have to, magnets are cheap and pretty acurate. Hope this helps. Wes

[MattBower]

Hmm. I think part of the problem here is that the term "normalizing" is not very clearly defined.

When I do a normalizing cycle on simple high carbon steel I do the first cycle to around 1600-1700 F, then allow to air cool well into the black, but not to room temp. (The temperature doesn't have to be precise; it just needs to be hot enough to deliberately grow grain and help make it uniform.) The next two cycles go to 1550 and then 1500 to reduce grain size, cooling well into the black in between. All of these are non-magnetic temps, and at least orange to my eye. This is a pretty typical normalizing strategy for bladesmiths. It produced the grain structure you see in my pic above, which was just fine until I overheated the edge immediately prior to quenching. Grain grown does not begin until you reach full austenite, and it is far more sensitive to temperature than to time. Take a look at this O1 held at 1510 F for five hours, then quenched and broken. (This was done just to prove the point that temperature matters far more than time when it comes to grain growth.) The grain is superb. So I can't agree with the claim that you should never see orange when you normalize. If you're not making austenite, I don't think you're refining grain.

[Mark Wargo New2bs]

Thanks guys, I appreciate your knowledge. It certainly helps me on my learning curve.

Mark

[Sukellos]

I use leaf spring steel. But I just heat to critical and let it air cool. Plenty of spring, haven't had a break yet.

Now watch, just cuz I said that....

[viking-sword]

I guess it does depend on each persons shop and the lighting they choose as temps between 1500 and 1700 are not quite in the orange range( though I guess I'd have to say it's redish orange when right at 1700), at least in my shop, which is why a magnet is always a good idea. If you ever have the chance to experiment with a good calibrated digital heat treat oven, take a magnet and your prefered steel your using and observe the colors as they approach and then exceed critical temp(non magnetic) to see just how they look at those temps. Do try to adjust the shop lighting to closely resemble your shop conditions, it's very educational. Wes

[MattBower]

This is why I use Tempilaq and Tempilstiks.

[viking-sword]

I've never had a chance to try them but I'm told they work well!

[Jack Evers]

Made my first spring hold down many years ago. I knew nothing, quenched in oil, broke immediately. Made the second, heated to non magnetic and air cooled, worked fine, made a couple more, still have all three.

[ThomasPowers]

Generally in edge too work you anneal when you plan to be working on the metal with file or grinder; afterwards you should do a normalization to relieve stress introduced by stock removal and deal with the anneal issues.

[MattBower]

I admit I'm lazy about annealing. I usually do stock removal with the steel in a normalized state, then when I'm ready for HT I come back and do the triple normalize and quench routine. It seems to work well enough, though I know stock removal might be slightly easier (and slightly easier on my tools) if I went ahead and annealed.

[mike-hr]

Don't know if this applies to your project, but a lot of failures I've seen when working with spring steel originated from beating and bending after the steel cooled too much, and got into the feared blue brittle range. I try really hard to only work steel when it's red. If I can't see red, it goes back in the fire.

[Mark Wargo New2bs]

Well, while working at the forge today I grabbed those two broken pieces and normalized one, while leaving the other as a control. After three cycles of successively lower heats I brought one piece above critical and quenched it, then broke it with a hammer. Lo and behold, the grain structure was small and silky smooth. I'm amazed, they don't even look like they are made from the same material. I was worried that just eyeballing the color would not produce good results on normalizing, but wow was it much improved. Thanks for all the advice.

Mark

[Iron Clad]

It is a great learning experience about working high carbon in this case, however you don't have to make fullers from this material. Low carbon will work just fine.

I made this spring fuller a couple of weeks ago from mild steel, the plans of which came from Mark Aspery's book "fundamentals of leaf work'.

http://ironclad.shutterfly.com/43

I have made many spring fullers over the years and always out of mild steel. It's cheaper, and when they wear out, just make another.

[Mark Wargo New2bs]

Thanks, I will probably do that. I used a spring steel because it's a spring fuller LOL. I live and I learn. I will probably make a fuller like the one you did, I like that alot.

Mark

[Refuz]

It is a great learning experience about working high carbon in this case, however you don't have to make fullers from this material. Low carbon will work just fine.

I made this spring fuller a couple of weeks ago from mild steel, the plans of which came from Mark Aspery's book "fundamentals of leaf work'.

http://ironclad.shutterfly.com/43

I have made many spring fullers over the years and always out of mild steel. It's cheaper, and when they wear out, just make another.

That's really nice. I need to get some of his books myself.