I am sure this Q has been asked before, not much on web about it. So I'll ask here
I unfortunately have three top cylinder fins - at the outer front corner - that are bent at about a 45 degree angle for a hort distance. I was thinking of annealing them -heat to ~700F, let cool. This should make it more malleable before straightening bent fins?
Anyone try this on cast aluminum fins? I have straightened fins that were bent slightly but, most of the time the fin just snaps off
You might want to talk to someone at a nearby heat treating company. If I'm not mistaken, I don't think you can anneal cast aluminum. Even top notch stuff which these aren't.. Forged yes, cast no. Cast has a crystalline structure and is brittle by nature. I don't think you can change that. How it ever gets bent without snapping off is beyond me. Good luck! I've been wrong before.
I was born with nothing and still have most of it left.
This one is amazing -> https://www.youtube.com/watch?v=9moYO-WWhaQ" onclick="window.open(this.href);return false;
A temperature crayon is more accurate (than soap or soot), but what temp 700F
I tried one fin and it seems my propane torch doesn't get it hot enough. My understanding anneal is just as the point before it should melt
Coyote wrote: I don't think you can anneal cast aluminum.
I fear you may be correct. I have never had luck doing this when bad... snap!
There is no nearby heat treating CO. Suppose I could try to call one. I'm all googled and youtubed out on this one
I tried one fin and it seam my propane torch doesn't get it hot enough; Fin is doing its job pulling the heat away? My understanding anneal if possible is just as the point before it should melt the metal. I need a hotter torch! I did bend it back 70% of what it was. I was surprised! I went real easy and slow a little at a time.
I think the key is patience (damn and I have adult ADHD). Kind of like straightening teeth with orthodontist applied braces tentioned lightly over months versus using a pair plyers trying to do it in a couple minutes. Crack - Broke my tooth!
And that would suck almost as bad as cracking a shiny fin on a T350 cylinder.
My understanding anneal if possible is just as the point before it should melt the metal.
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Not really. Annealing is done post heat treat. Also known as drawing it back. Different temps and soak times depending on the material and the Rockwell hardness required by the customer. Some materials anneal at only 300 degrees. Most metals are heat treatable except for 300 series (bright) stainless steel. 400 series stainless is heat treatable and widely used - especially on cutlery. When you get your shiny new pen knife and the word stainless is on the blade. you are looking at heat treated 400 series stainless. Although 300 series is brighter and takes a super polish, it is soft and easily marred or scratched. 300 series is also totally non magnetic. On the other hand, 400 series has 'some' magnetism, but not as much as plain old cold rolled steel.
If it sounds like I know a little bit about it, I was in a related industry for 30 years.
I was born with nothing and still have most of it left.
I would take heart from the fact it was malleable enough to bend in the first place so if should be able to be returned to the same state. Difficulties come from how, if you could get access to the kit a hardness tester and and oven you could measure pre and post heat treatment the hardness see what effect you are having. You could then start with lower end temps and work upwards.
I don't know exact theory but within short time it works.
I used Map Pro propane torch versus just Propane (think this works too). Map pro is a little hotter. It will make plan soap turn black as a temperature test per “rule of thumb “ And, even if you stay on it longer (no need to though) it won’t melt the fin. Once hot, I just let a house fan blow air on it to cool. This took the most time.
As you know, if you muckle on to a fin, it will bend some, but make too much travel its snaps. That has happened to me many times. When you heat it, let it cool it bends very easy, but for a short distance and then you will feel it tighten up again. Stop at that point! Heat and cool again. The process can be repeated. I did this 4 or 5 times. Other fins in the area get soft too, but just wiggle up and down a little and it stiffens up and gets strong again. I bought a set on metal bending pliers look like needle nose but, don't come to a point and stay straight. That allows you to work it a little better. Take your time and stop when it bends harder. The process is fast and I had somewhere between 1 -2 hours into it only.
I think I got it, how to add pics like you coyote.
If I had two flat metal working pliers at the time I could have done it better. I'll pick up another and do a touch up maybe. But isn’t bad. Those three fins were laid over quite a bit and others were off and fixed them up too. I'll use aluminum brighter and all should clean up well. Got lucky this time
