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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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4140 - heat treat?
I made a bolt for the kickstarter of a friend's motorbike, as the
standard ones always bend. Used 4140 high-tensile steel, but now thinking it might be improved by heat treatment. But I've virtually no experience with this process, so: Does it make sense, given that there is a thread on the bolt? Will scaling or warping change its size and shape? Is it easy enough to do? Thanks Jordan |
#2
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4140 - heat treat?
"Jordan" wrote in message u... I made a bolt for the kickstarter of a friend's motorbike, as the standard ones always bend. Used 4140 high-tensile steel, but now thinking it might be improved by heat treatment. But I've virtually no experience with this process, so: Does it make sense, given that there is a thread on the bolt? Will scaling or warping change its size and shape? Is it easy enough to do? Thanks Jordan Yes, it's fairly easy to do, but without a controlled atmosphere furnace, or stainless foil, your chance of not screwing it up is not good. For one, when you heat and soak the part as prescribed, you'll experience some decarburization, and scaling will pretty much ruin the surface. Warping can be controlled somewhat by proper quenching, but even that can be filled with surprises. Chrome moly can be heat treated by torch, but you'll still experience considerable scaling. If you'd like to try, heat to 1525/1625 F, and quench only in oil. I don't have a clue regards drawing it after quench. I've always had heat treat done by a certified heat treat facility, of necessity. A good choice for the job you did is to use some pre-heat treated 4140. As I recall, it comes hardened to somewhere between 28 and 32 Rc-----tough, but quite machineable. Harold |
#3
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4140 - heat treat?
Thanks Harold.
After this info, I daren't try heat-treating it myself. Your suggestion to use pre-h'treated steel is noted for future reference. Jordan |
#4
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4140 - heat treat?
Harold and Susan Vordos wrote: "Jordan" wrote in message . au... I made a bolt for the kickstarter of a friend's motorbike, as the standard ones always bend. Used 4140 high-tensile steel, but now thinking it might be improved by heat treatment. But I've virtually no experience with this process, so: Does it make sense, given that there is a thread on the bolt? Will scaling or warping change its size and shape? Is it easy enough to do? Thanks Jordan Yes, it's fairly easy to do, but without a controlled atmosphere furnace, or stainless foil, your chance of not screwing it up is not good. For one, when you heat and soak the part as prescribed, you'll experience some decarburization, and scaling will pretty much ruin the surface. Warping can be controlled somewhat by proper quenching, but even that can be filled with surprises. Chrome moly can be heat treated by torch, but you'll still experience considerable scaling. If you'd like to try, heat to 1525/1625 F, and quench only in oil. I don't have a clue regards drawing it after quench. I've always had heat treat done by a certified heat treat facility, of necessity. A good choice for the job you did is to use some pre-heat treated 4140. As I recall, it comes hardened to somewhere between 28 and 32 Rc-----tough, but quite machineable. Harold A useful trick is to rub soap (plain bar soap) over the metal surface. It won't prevent discoloration and a small amount of oxidation, but it will prevent any significant scaling. Depends on the item, try on a spare piece first... Steve |
#5
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4140 - heat treat?
Jordan wrote: I made a bolt for the kickstarter of a friend's motorbike, as the standard ones always bend. Used 4140 high-tensile steel, but now thinking it might be improved by heat treatment. But I've virtually no experience with this process, so: Does it make sense, given that there is a thread on the bolt? Will scaling or warping change its size and shape? Is it easy enough to do? Thanks Jordan If you got an oxy/acytlene torch, a magnet, and a bucket of oil you can easily heat treat it. Set the torch with a reducing flame, one which there is an excess of carbon. This will keep the metal from oxydizing. Heat the metal until the magnet will not attract the steel. This is the point where the steel changes...I forget what to what, but at that point you want to quench the piece immediately. By the way, make sure you quenching oil is about 140 degrees or the piece will chill too fast and crack. Also, when you immerse the piece in the oil, do not pull it back out because the smoke will flash and burn. Keep moving it while holding it under the oil until it is cool. It will be in the full hardened condition, for 4140 that will be about 56rc rockwell. Now you got to draw, temper, anneal it, choose a word. What you do is to heat it back up to about 600 degrees and then let it cool. 600 degrees is when the metal turns a very light straw color. Sand off a place so you can see the color change easily. I would practice on a piece first before you do a finished piece. John |
#6
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4140 - heat treat?
Wow, thanks John.
Sounds like alchemy! Jordan If you got an oxy/acytlene torch, a magnet, and a bucket of oil you can easily heat treat it. Set the torch with a reducing flame, one which there is an excess of carbon. This will keep the metal from oxydizing. Heat the metal until the magnet will not attract the steel. This is the point where the steel changes...I forget what to what, but at that point you want to quench the piece immediately. By the way, make sure you quenching oil is about 140 degrees or the piece will chill too fast and crack. Also, when you immerse the piece in the oil, do not pull it back out because the smoke will flash and burn. Keep moving it while holding it under the oil until it is cool. It will be in the full hardened condition, for 4140 that will be about 56rc rockwell. Now you got to draw, temper, anneal it, choose a word. What you do is to heat it back up to about 600 degrees and then let it cool. 600 degrees is when the metal turns a very light straw color. Sand off a place so you can see the color change easily. I would practice on a piece first before you do a finished piece. |
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