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Heat treating help
- Thread starter weld
- Start date
- Joined
- Dec 13, 2000
- Messages
- 265
Haven't tried springs but 440c can be HT with a torch. Heat to 1850, oil quench until no longer red, rapid air cool in front of a fan narrow edge into the breeze. Immediately temper, air cool, temper, cool again.
The problem may be finding the right temper temp. The Crucible Orange book says 1000 degrees will give Rockwell 51C and stops there. The risks with thin and small sections are cracking, heat riser cracks and warping.
440c will form a scale this way which is harder to remove than most non-stainless alloys.
I know they make firearm springs out of stainless but don't know the alloy. Looks like 420 stainless can be ht to RC49-53.
The problem may be finding the right temper temp. The Crucible Orange book says 1000 degrees will give Rockwell 51C and stops there. The risks with thin and small sections are cracking, heat riser cracks and warping.
440c will form a scale this way which is harder to remove than most non-stainless alloys.
I know they make firearm springs out of stainless but don't know the alloy. Looks like 420 stainless can be ht to RC49-53.
- Joined
- Oct 1, 2000
- Messages
- 244
Well I have made folder springs out of 440C using a torch. I started out hardening by heating to floresent or translucent orange yellow color. (Remember color is subjective and varies based on available light.) Rapid cooling in front of a fan. You could oil quench but don't really need to on 440C.
Ok the tempering. I used an old blacksmith book that talked about colors. Wished I had made me a copy of that table. Or at least remembered the name of the book.
Sand the metal down to shiney steel. Make sure there are not any deep scratches or nicks in the spring or I promise you it will break right there. Use a small propane torch and heat the sping to just past dark bronze where the metal is starting to turn bright blue. Heat SLOWLY and EVENLY, wave the torch under the metal and then watch closely. It takes a little time for color to change. Don't heat to the gray color (just past the bright blue) or you get's to do hardening again. Once at the bright blue color stop. Let the spring cool down to room temperature. I would temper like this about 3 or 4 times. You will have to sand the color off between each temper, but that is pretty easy. Be sure to heat slowly so the temperture is consistant through the metal and not just a surface color change. This ought to get you to a spring temper. Try some scrap pieces first and then clamp in a vise and flex them. See how much it takes to break them. Use this as a starting point and experiment a little first.
I did this on my first few folders until I got my oven. I wouldn't go back to a torch now. An oven will give you much better results but the black smith way will work to you just have to experiment some.
Hope this helps.
Ok the tempering. I used an old blacksmith book that talked about colors. Wished I had made me a copy of that table. Or at least remembered the name of the book.
Sand the metal down to shiney steel. Make sure there are not any deep scratches or nicks in the spring or I promise you it will break right there. Use a small propane torch and heat the sping to just past dark bronze where the metal is starting to turn bright blue. Heat SLOWLY and EVENLY, wave the torch under the metal and then watch closely. It takes a little time for color to change. Don't heat to the gray color (just past the bright blue) or you get's to do hardening again. Once at the bright blue color stop. Let the spring cool down to room temperature. I would temper like this about 3 or 4 times. You will have to sand the color off between each temper, but that is pretty easy. Be sure to heat slowly so the temperture is consistant through the metal and not just a surface color change. This ought to get you to a spring temper. Try some scrap pieces first and then clamp in a vise and flex them. See how much it takes to break them. Use this as a starting point and experiment a little first.I did this on my first few folders until I got my oven. I wouldn't go back to a torch now. An oven will give you much better results but the black smith way will work to you just have to experiment some.
Hope this helps.