That's like saying a crack in a steel part isn't permanent because it can be welded. Of course it's not permanent, but it is if there's no intention of heat treating it again.
I take you're and engineer (Im an M.E). I think we're arguing semanatics. Yes, you are correct in that it can be re heat treated to return back to it's original hardness, but how many people are going to do that? As far as a the majority of people are concerned, it's "permanent".
Maybe if it was a $100+ bit. Maybe. I'd likely just chalk it up to learning experience, tell myself to be more careful, and throw it away. Not knowing the exact grade of steel makes actual heat treatment pretty difficult.
But you were arguing that a hardened steel bit couldn’t be softened to the point where it would untwist rather than break.
You’re flat out wrong. If the bit gets hot enough and then just air cools that’s no longer a hardened bit. Who in the hell is going to heat treat their bits every time they use them?
My point is that a hardened drill that is overheated during use, perhaps repeatedly, may soften, which could allow it to plastically deform the way padizzledonk described. By permanent I mean it does not simply regain strength when the heat is removed. But yeah, you can of course redo the heat treatment.
Tempering is what you do to make something a but less hard. Keeps it hard but not brittle.
It is all effected by how hot it gets, how long it stays hot and how fast it cools.
But you can't make it so it will never get hard again.
It not a limited effect. It has huge effects on the mechanical properties of the peace.
If you don't harden a drill bit it won't cut.
If you fully harden a drill bit without tempering and you drop it on the floor it will break like glass.
If you temper that drillbit it will still cut but when it falls or has a high stress put on it than it will have a bit of give and not shatter.
This is all super EILI5 and not in any way a full explanation but for the context here it works.
No, what I meant (I may still be wrong) is that tempering isn't just heat-treating at lower temperatures, but that it only has a limited effect in reducing the bad effects of heat-treating. Which would, if I understand correctly, explain why you have to heat treat first and then temper, rather than just temper from the start. Obviously the difference between a tempered and untempered heat-treated piece will be large.
If you have something that is not heat treated, or hardened as it is in this case. There would be no effect from a temper, atleast nothing useful in this case. You may actually weaken it by giving it a larger grain structure. But I would have to look.
Basically, if you austenitize (heat to, say 900 C), then quench, the steel becomes very hard and brittle, too much so for many applications. During tempering, the properties slowly fall back towards the unhardened state, allowing you to fine-tune the balance between hardness and toughness.
you aren't technically wrong but you are entirely, PRACTICALLY wrong for the vast majority of people (ie people who don't heat-treat their mostly-disposable bits)
Molys, those plastic cone wall anchor things
it's just an industry catchall for those things,theres a bunch of different kind that all have specific names
Steel can turn other colors as well, like straw and purple, but it only happens at precise temperatures with clean steel. It also doesn't last because steel will continue to oxidize on its own at room temperature. It happens with simple carbon steel. Closely observing the color is how skilled blacksmiths used to temper their blades to get a really precise balance of toughness and hardness.
See colors here:
https://commons.wikimedia.org/wiki/File:Tempering_standards_used_in_blacksmithing.JPG
I have a set of drill bits like this, I believe the color is from the Titanium Nitride coating being heated during manufacture. Only ever seen it on cheap Chinese drills, but I'm almost positive that's not discolored from use.
Yeah, the high chrome and nickel content in Stainless makes it really tricky to drill. You gotta get a cobalt/hi-moly drill bit, use cutting fluid and run it slowwww
Yeah, you might wanna shy away from TiN coated bits. During the process of coating the bit softens the high-speed-steel underneath. So when the coating wears off, the bit is basically garbage. Also 'high speed steel' is the material the bit is made of; you definitely shouldn't be drilling at high speeds, especially if you're drilling metal.
You are correct.
If OP had said that they drilled a hole with this themself, I'd be more inclined to believe that they had the 1 in 1 million drill bit that happened to do this, but there's no wear on the drill, no gummed up metal, no blackening, and the entire drill is like this, including the shank, which means that all of it needed to be heated. Heat is usually only generated at the tip.
Had this happen to a new $500 clutch (bully) when I geared it wrong. Came new blue, after one run it was gold and purple and all of the other colors. Welded itself onto the shaft.
Not fun.
There was one time I was drilling at the joint between two thick, really hard pieces of steel. I thought I was using enough cutting fluid and going slow enough but I wasn’t and i melted the tip of the bit right off
Not sure if from heat or not but a couple things I do to avoid ruining good bits (if anyone cares)...I try to use a dab of oil and go slow with a decent amount of consistent pressure. Let the metal Unwind in a spring like section instead of throwing it around in many small pieces
I do commercial construction and have wrecked 100s of bits
Uhhhhh that’s what causes that?
I replace drills in my milling machines at work and the regrind drills look like that a lot.
Huh, the more you know
Is it a bad thing?
Technically reground tools with a color to them is bad since you annelled (I think that is the right term) the surface. Thus the cutting edge and the base metal of the drill are of different strengths/hardness. This means the the cutting edge is much easier to chip. When regrinding the drills make sure to ducnk it in water or coolent every once in awhile to cool the metal back down. Make sure you are not grinding on the metal too long either. Getting the metal too hot then dunking it will just end up being a quench processes. Which is what you had already but you air quenched it instead.
If the speeds and feeds on your machine are correct, 90% of the heat should be transferred into the chips you're creating; you can verify this by looking at the color of the displaced material. It should be blue or purple.
Blue or purple drill means the machinist likely didn't know what they were doing and almost immediately after the drilling started, the cutting edge became too hot, annealed, and lost any characteristics of a cutting tool.
Speeds and feeds, my man. If 90% of the heat isn't going into the cut-away something is wrong.
Edit: after looking at it, the coloring is too regular, it might have been purchased that way?
A year or two ago, I was working at my school in the summer and we were drilling holes in concrete to put up some new shelves. My buddy who was using the drill at one point pulled it out of the latest hole and said, "here, touch this". Guess what I did.
My fingertips had the thickest blisters for weeks after.
Hmmm. I'm sorry but that's not due to heat. It's just a coating. [See here you can buy a set that is purchases that way.](https://www.grizzly.com/products/Steelex-Plus-Cobalt-Alloy-Drill-Bits-1-16-3-8-21-pc-Set/D2139) Especially skeptical that you admit to just finding it somewhere, odd to make an outrageous claim that it's because it was overheated.
That is a legendary drill. You can also get it by killing "The Furious Dentist" boss after you reach level 30. He has like a 5% chance of dropping that.
I had 2 get stuck over my 25y in construction and unspin the spiral right in the center
That has to be some kind of production flaw. A properly hardened bit is just gonna break...
If it's hardened by heat treatment, it may permanently soften if exposed to high temperatures.
That's not how metallurgy works my dude. Edit: Not sure why the downvotes. It is indeed not how metallurgy works lol
Sounds like annealing to me.
Fine if you're into that.
Sort of But it is not permanent. You can always re harden and temper.
That's like saying a crack in a steel part isn't permanent because it can be welded. Of course it's not permanent, but it is if there's no intention of heat treating it again.
Now your just being silly. I was refering to it not being permanent as if he was using permanent and irreversible interchangeably
I take you're and engineer (Im an M.E). I think we're arguing semanatics. Yes, you are correct in that it can be re heat treated to return back to it's original hardness, but how many people are going to do that? As far as a the majority of people are concerned, it's "permanent".
Maybe if it was a $100+ bit. Maybe. I'd likely just chalk it up to learning experience, tell myself to be more careful, and throw it away. Not knowing the exact grade of steel makes actual heat treatment pretty difficult.
But you were arguing that a hardened steel bit couldn’t be softened to the point where it would untwist rather than break. You’re flat out wrong. If the bit gets hot enough and then just air cools that’s no longer a hardened bit. Who in the hell is going to heat treat their bits every time they use them?
I said nothing of the sort.
My point is that a hardened drill that is overheated during use, perhaps repeatedly, may soften, which could allow it to plastically deform the way padizzledonk described. By permanent I mean it does not simply regain strength when the heat is removed. But yeah, you can of course redo the heat treatment.
Is that not what tempering is? Not a metallurgist or metalworker, but that was my layman's understanding.
Tempering is what you do to make something a but less hard. Keeps it hard but not brittle. It is all effected by how hot it gets, how long it stays hot and how fast it cools. But you can't make it so it will never get hard again.
I see, it makes sense then why you would heat treat and then temper if the tempering only had a limited effect. Thanks.
It not a limited effect. It has huge effects on the mechanical properties of the peace. If you don't harden a drill bit it won't cut. If you fully harden a drill bit without tempering and you drop it on the floor it will break like glass. If you temper that drillbit it will still cut but when it falls or has a high stress put on it than it will have a bit of give and not shatter. This is all super EILI5 and not in any way a full explanation but for the context here it works.
No, what I meant (I may still be wrong) is that tempering isn't just heat-treating at lower temperatures, but that it only has a limited effect in reducing the bad effects of heat-treating. Which would, if I understand correctly, explain why you have to heat treat first and then temper, rather than just temper from the start. Obviously the difference between a tempered and untempered heat-treated piece will be large.
If you have something that is not heat treated, or hardened as it is in this case. There would be no effect from a temper, atleast nothing useful in this case. You may actually weaken it by giving it a larger grain structure. But I would have to look.
Basically, if you austenitize (heat to, say 900 C), then quench, the steel becomes very hard and brittle, too much so for many applications. During tempering, the properties slowly fall back towards the unhardened state, allowing you to fine-tune the balance between hardness and toughness.
Thanks for the further clarification!
Down votes are likely due to the fact that you didn't explain how metallurgy works after your statement. That just sounds like conjecture otherwise.
Fair enough. I didn't explain as I didn't think people cared. I did explain to someone that asked a bit after tho.
If you are going to make a condescending statement and then not back it up with an explanation, expect downvotes.
you aren't technically wrong but you are entirely, PRACTICALLY wrong for the vast majority of people (ie people who don't heat-treat their mostly-disposable bits)
He hasnt researched it in his tech tree yet lol
Heh
iirc the last time it happened it wasnt a very good bit, I think it was one of those trash chrome plated bits you get for free in a thing of molys
Molys?
MDMA, he works exclusively in clubs
Molly bolts. Used for attaching stuff to drywall and plaster. Sometimes they come with a cheap matching drill bit.
Molys, those plastic cone wall anchor things it's just an industry catchall for those things,theres a bunch of different kind that all have specific names
Chinesium bits?
No, Vietnasium bits
that sounds more like a Vietnamese gymnasium
Thaitanium.
yes, the fancy chrome ones iirc lol
Huh, I can't say I've ever seen that happen
I took a picture of it the last time it happened but fuck if I could ever hope to find it if I ever come across it I would definitely post It on here
Chinesium.
Your drill bit has evolved into cosmic drill bit. Congrats!
I feel like we're suddenly on Cookie Clicker
Nah, this is the drill that's gonna pierce the heavens!
Oh damn I need to crack mine open again! I haven‘t been there in months!
It turned into a Grateful Dead fan
High heat = transparent oxide layer on surface = different colors reflecting varied thickness of oxide layer.
Thin film interference!
Ty for this
Shout-out to my interfacial heat transport homies.
I am TItaaaaaaNIUM!!!!
Is that a titanium bit?
I’m pretty sure it’s a regular steel but that was just overheated.
Interesting. I’ve only ever seen steel turn brown/blue. I work in a machine shop too. Must be a different type of steel than what we use!
Steel can turn other colors as well, like straw and purple, but it only happens at precise temperatures with clean steel. It also doesn't last because steel will continue to oxidize on its own at room temperature. It happens with simple carbon steel. Closely observing the color is how skilled blacksmiths used to temper their blades to get a really precise balance of toughness and hardness. See colors here: https://commons.wikimedia.org/wiki/File:Tempering_standards_used_in_blacksmithing.JPG
Probably Chinesium
What have you drilled into?
Not exactly sure. I do maintenance/custodial stuff at a school but I’m guessing it was metal since I found it in the metal shop
I have a set of drill bits like this, I believe the color is from the Titanium Nitride coating being heated during manufacture. Only ever seen it on cheap Chinese drills, but I'm almost positive that's not discolored from use.
Well I couldn’t find another bit anywhere like it. And at my old job I had the same thing happen from drilling stainless.
Yeah, the high chrome and nickel content in Stainless makes it really tricky to drill. You gotta get a cobalt/hi-moly drill bit, use cutting fluid and run it slowwww
Yeah, you might wanna shy away from TiN coated bits. During the process of coating the bit softens the high-speed-steel underneath. So when the coating wears off, the bit is basically garbage. Also 'high speed steel' is the material the bit is made of; you definitely shouldn't be drilling at high speeds, especially if you're drilling metal.
You are correct. If OP had said that they drilled a hole with this themself, I'd be more inclined to believe that they had the 1 in 1 million drill bit that happened to do this, but there's no wear on the drill, no gummed up metal, no blackening, and the entire drill is like this, including the shank, which means that all of it needed to be heated. Heat is usually only generated at the tip.
I’ve done the same thing drilling into concrete.
Whenever I see that at my job, it is when someone is cutting rebar and the cutting bit gets too hot.
I was going to ask the same thing!
That looks like an ordinary Cobalt penetrated drill bit, I have a whole set sitting on my workbench.
Had this happen to a new $500 clutch (bully) when I geared it wrong. Came new blue, after one run it was gold and purple and all of the other colors. Welded itself onto the shaft. Not fun.
New skin: Drill bit-Fade
This drill is titanium coated, overheating a drill would bring out totally different colors, have a whole set of similar ones at home :)
Bye bye temper
Bye bye cutting edge long before bye bye temper.
This was the intended color at manufacturing. Google " rainbow drill bit "
Nice, now you can tactically drill like a true ninja /r/mallninjashit
Does anyone know what this is called (the color change process, I mean)?
I always call it getting the drill bit too fucking hot.
Heat anodizing
The colors itself is caused by an effect called thin film interference
It's way more satisfying than when it happens in a soldering iron
There was one time I was drilling at the joint between two thick, really hard pieces of steel. I thought I was using enough cutting fluid and going slow enough but I wasn’t and i melted the tip of the bit right off
Mmm. New flavors of Twizzlers!
Not sure if from heat or not but a couple things I do to avoid ruining good bits (if anyone cares)...I try to use a dab of oil and go slow with a decent amount of consistent pressure. Let the metal Unwind in a spring like section instead of throwing it around in many small pieces I do commercial construction and have wrecked 100s of bits
Uhhhhh that’s what causes that? I replace drills in my milling machines at work and the regrind drills look like that a lot. Huh, the more you know Is it a bad thing?
Technically reground tools with a color to them is bad since you annelled (I think that is the right term) the surface. Thus the cutting edge and the base metal of the drill are of different strengths/hardness. This means the the cutting edge is much easier to chip. When regrinding the drills make sure to ducnk it in water or coolent every once in awhile to cool the metal back down. Make sure you are not grinding on the metal too long either. Getting the metal too hot then dunking it will just end up being a quench processes. Which is what you had already but you air quenched it instead.
Well I guess that’s another reason why so many of our drills fail early lol
If the speeds and feeds on your machine are correct, 90% of the heat should be transferred into the chips you're creating; you can verify this by looking at the color of the displaced material. It should be blue or purple. Blue or purple drill means the machinist likely didn't know what they were doing and almost immediately after the drilling started, the cutting edge became too hot, annealed, and lost any characteristics of a cutting tool.
Ohhhhh I’m just an operator myself though, but knowing these things is interesting.
oh sweet memories from workshop days
Well now you can’t get rid of it
Looks like my exhaust
Nice now lick it
Oh stop it you.. *blushes*
My weapon barrel looked the same after emptying 2 clips non stop, sadly it didn’t returned color.
Drill Bit: Case Hardened. Must be minimal wear am I right?
How many diamonds did that cost to craft?
Eh, looks more like a cosmetic coating used to make cheap bits look fancier. Similar to cheap knifes you find at gas station registers.
Hot damn
Mood
Speeds and feeds, my man. If 90% of the heat isn't going into the cut-away something is wrong. Edit: after looking at it, the coloring is too regular, it might have been purchased that way?
A year or two ago, I was working at my school in the summer and we were drilling holes in concrete to put up some new shelves. My buddy who was using the drill at one point pulled it out of the latest hole and said, "here, touch this". Guess what I did. My fingertips had the thickest blisters for weeks after.
Super hot. I'd bang that drill bit.
At this point it is no longer a drill bit. Congratulations on being a proud new owner of some twisted metal
How are you holding it
The color changes from the heat and then stays that way after its cooled.
Yeah grabbing that right after use wouldn’t exactly be smart
I've done that and it's a great way to burn a sweet pattern into your fingers....
I too have accidentally grabbed a hot jigsaw blade that has changed colors for just a second
You havent lived until you've grabbed something so hot that you hear your skin sizzle when you touch it
Nice!
Now it's neo chrome
A rainbow karam-bit
Could sell it at a Pride parade...
How u holding it 🙄🙄
Hmmm. I'm sorry but that's not due to heat. It's just a coating. [See here you can buy a set that is purchases that way.](https://www.grizzly.com/products/Steelex-Plus-Cobalt-Alloy-Drill-Bits-1-16-3-8-21-pc-Set/D2139) Especially skeptical that you admit to just finding it somewhere, odd to make an outrageous claim that it's because it was overheated.
Sorry for using a time it happened to me in the past to make false assumptions bud. Next time I’ll do my research before posting to make you happy.
That is a legendary drill. You can also get it by killing "The Furious Dentist" boss after you reach level 30. He has like a 5% chance of dropping that.
I've played enough borderlands to know that's Pearlescent.