I was using heat to remove a spindle arm bushing. It got hot enough that it turned the end of the arm blue. Has that damaged it?
Tom, I have spent a lot of years urging metal to do what I want it to do. Does that qualify me as a metal-urgist? When that arm was forged, considerably more heat was involved than you used, so I suspect you have caused no damage. Other opinions may vary.
Allan from down under.
Should not have unless you held it there for hours and hours which you didn't.
Did you by any chance polish it up a bit so you could see good before you tried the heat? If so, the blue could have been in a new air oxide layer forming and really was warm not overly hot and then just cosmetic.(fresh oxide behaves different)
Blue leaning towards purple...to blue like in razor blade is about 550-600 degrees. So that c/would have been a quick temper as opposed to any hardness change and it probably air cooled. I wouldn't worry about it.
Thanks Allan and George for your responses. I did bead blast it before I put the heat to it. The very outside edge was red hot, and I did allow it to air cool.
Welcome, and Allan...sorry mate....that 550-600 was that thing called Fahrenheit
I am probably wrong Herm but if it has not been heat treated to increase strength you are all right. Even if heat treated 600 degrees is not a problem.
Tom the only way to tell if you really hurt it or not is to take it to someone with a hardness tester. The railroad is where I use to get mine done at their shop where they tested track. (Frisco). Check the very end where the threads aren't and then ck the king pin upright that you did not heat. Rockwell or Brinell scale will tell you for sure. We have had Ford cranks turn blue in a fire and the aluminum heads were not seemingly touched. The crayon??? markings on the heads and the paper stickers were still on the head. So everything was ok...right? Only the plastic valve cover on one side was burned and the rubber on the harmonic balancer was too. Hardness tests showed that both heads and the crank and 3 of the connecting rods were ruined. This is all I know on the matter. So heat can fool you. This was because of a transmission fluid fire. It was put out within 6-7 minutes. Burned the hood off of the car too. Heat goes up right? 1998 Cobra.
Next time just cut it length wise and it should drive right out. You should be able to get a hack saw blade in the hole, if not, grind a little off the back of the blade.
Your temp range wasn't high enough to do any damage. I have no idea what Henry would have used for hardness requirements. Heat treating that particular part shouldn't have been necessary. If Henry used a stressproof type of material to increase tensile strength it would probably have been a 30 t0 32 rockwell c. It's a crazy kind of thing but you can actually stress relieve a piece of steel by sand blasting it and doing it after heating it and letting it cool would take any stress from the heat out of it. If you do plan on testing the hardness on a rockwell be sure to grind the area where you're going to test. That will take any carbon embrittlement that may exist on the first .030" depth on the outside of the part. All that being said I figure your in good shape. One thing you might want to do just for giggle is take the part to a machine shop with a good magnetic particle inspection machine (aka magnaflux). The operator will be able to tell you if the forging has any carbide stringers or cracks in it. Or just put it back on the car, genuflect in the direction of your St Christopher medal, make the sign of the cross while looking at your plastic dash Jesus, say a few hail Mary's and drive on.
Loved that last line! LOL
Thanks Mark. I was hoping no-one would become too offended. I have too easy a time doing that sometimes.
MIke, as an act of attrition, you can put the bronze thrust washers in my differential!!!
Lucky you, you're too far away!!!!
Now I've probably offended someone--but I really didn't mean to--I just couldn't resist ribbing you!
PS If T-Monk was still around, you could have made some donations to his Orphan's fund. . . . .
Thanks all for your advise. I guess in the back of my mind it would always be an issue. I did try and cut it with a hacksaw, it didn't do much more than scratch it before I put the heat to it. I dug out another one and I guess I will use that. This time I will tap it, screw a bolt in it, and see if I can drive it out that way.
Once you start cutting with a saw and get through the top layer it goes good. The surface is work harden only as far as I can tell. A "GOOD" fine tooth blade works best.
Make sure you have a "bi-metal" blade. They will cut much harder material and last much longer than a regular blade. Dave
Mike don't care if it rains or freezes long as he's got his plastic Jesus glued on to the dash board of his car...
Mike that was good information for Tom. Usually when I get my parts back from the heat treaters there is a place ground off where the mark went. That is right to get below to virgin surface.
After I sent it in on this thread I remembered to tell you guys when using a torch be very CAREFUL!!! An ounce of judgment and protection is a REAL reward here. Heat only the edges of the part to be removed NOT the whole damned part!!! Get it red I even use a rag cooled in h2o to keep the other parts cool. Just wipe it down a few times. Not the part you are heating! You can use a chisel to start it moving be selective and tap both sides 180 degrees from each other. I also sometimes use the O2 lever and blow half of the old part off too. It will all work out in the end.
No the Ford Co did not heat treat those axle stubs. You just do not want to loose what temper it has. Nor yours either!!!
Hope this helps. I try not to saw things unless it is necessary.
Hey just because I taught this stuff in restoration classes doesn't mean I know anything LOL
Joe in Mo.