Damascus welding in induction forge

[ThomasPowers]

Boy I *love* the easy ones!   I do IT support and I love it when it's just a typo the customer made entering something.  I tell them "Don't be embarrassed. anything we can fix without needed a multi day trudge through error logs and googling help pages and spending 4 HOURS on the phone to YYYYYYYY Support, (Dropped 3 times, transferred 4 times, talking to people who don't understand what you are saying; before finally getting someone who can send you a $6 part that wasn't sent with the original order and is mandatory to mount a SSD...) is a *good* problem!

[BIGGUNDOCTOR]

I have seen small amounts melted while suspended in the coil's magnetic field. It is just this liquid ball spinning in air....until the power is killed , then it drops like a rock.

[Frazer]

Levitating molten steel? Wouldn't molten steel no longer be magnetic...? 

[Purple Bullet]

Thomas - I know what you mean. There was a point in one of my many varied careers I did Intranet web development and support. I think my mistake would fall under what we used to classify as ID ten Tee.

Doc - I haven't seen that yet. I'm not sure my little 15 kw unit can do that.

I got some more of the canister off. There is a spot in the middle that I can't decide if it was a void in the powder, was under cooked or overcooked. I suspect overcooked since the middle would have gotten the hottest as I moved it through the coils. I also think that is why the canister is so hard to remove. The places that are easy were some of the places with the least heat. Once I'm done cleaning the outside I'm going to cut it in half through that bad spot and weld the two pieces together. If I was a real artist I would cut it all up in cross section and restack and weld with the ends of the cable visible in the sides. I still don't know if the interior is solid yet, though. Besides, I didn't make a large enough billet to lose that much.  The idea is intriguing. After the fish hook knife I may have to try that. 

[Purple Bullet]

OK, my billet is a bust. It fulfilled its primary function in that I am now confident I can solidify metal in a cannister using my induction forge. Once again material selection has latched its teeth to my posterior. The cable was rusty, but not all THAT rusty, just enough to hide the fact that it was galvanized. It had been probably been laying around for twenty or thirty years. The thing that should have clued me was the lack of grease. I figured the grease had all worn off, but if that were the case it should have been more rusty. I soaked the cable in diesel and then burned it off with a torch. That usually gets rid of most of the grease but it doesn't get it hot enough to burn off the zinc that remained on the inside. When I heated the cannister I did notice a strange blue flame coming out of my vent holes, but since this was my first canister billet I didn't know if that was normal. Fortunately, my ventilation system worked well and I suffered no ill effects. 

What I produced is solid, but I don't trust whatever resultant alloy it now is. It seems prone to crack. I can work it and can heat it to welding heat after removing the canister so in my mind, the question is answered. Next step - the fish hook knife. 

[Goods]

You already have the fish hooks? Sounds like there is a shortage here and are selling at a premium…

[Purple Bullet]

Goods - I ordered a variety pack a month ago. When it came in I was amazed how tiny some of those hooks were. They must be for catching minnows for bait. I'm not sure they would provide the volume I wanted so I added a couple of packs from a local store of different variety including some hoop style.

I tell you what, though. The last time I walked through the local Wally World Super Store there were so many bare shelves it reminded me of Russia in the '90s. Scary.

[Frosty]

I don't know much about induction forges other than really enjoyed using one some time ago. I don't know why the center of the billet would get hottest. 

I understand why yours didn't set in the center but I do not get the center should have gotten hotter than the outside.

Frosty The Lucky.

[Purple Bullet]

Frosty - I shouldn't have said "center," I should have said "middle". As the canister heats I move it back and forth through the coil, heating the middle more than the ends.

However, I'm learning. I made my fish hook billet today. As I've said, I'm brand new to canister pattern welding. I'm not sure all these steps were necessary, but this is what I did:

1.welded one end of canister and put a handle on it. 2. Load it up with WhiteOut and let dry over an hour. 3 Soak fish hooks in paint remover to remove any enamel or coating. 4. Burned off residue from hooks. 5. Put a little 1085 powder in the bottom of the canister, then started loading fish hooks. 6. Poured powder and hooks back out when I noticed big flakes of whiteout loose in the canister. (I don't think I'll use white out any more. If I hadn't noticed I would have had big cold shuts.)7. Brushed out as much white out as i could with a small wire brush. 8. Reload powder and fish hooks and weld up top. 9. Heat in induction forge (I heated more evenly to an orange heat by moving faster through the middle and pausing at the ends. I did this twice to get the CENTER of the canister as hot as the outside.) Then I got the end of the canister closest to the handle up to welding heat and lovingly caressed it with my 4.5 lb cross peen. I repeated for the middle section and the end. 10. Let cool slowly and started removing canister, It wouldn't all chisel off so I used an angle grinder to thin the remaining mild steel. I dipped it in acid to see how much mild steel was left. There is still a thin layer of mild steel on it but I expect that will go away in scale as I forge the blade or for sure when I put a grind on it.

I'm happy with it so far. It looks solid, but I'm not going to draw it out until I've shown it to the guy it is going to belong to. I find that folks appreciate it more when they see what it comes from. 

[Frosty]

Got it, middle of the billet makes perfect sense, that eases my muddle.

Did you forget to clean the oil off the inside of the tubing before you applied the white out? 

Frosty The Lucky.

[Purple Bullet]

Duh... yes. ID ten Tee all over again.

[Frosty]

It's easy to forget mill coatings and lubes. Been there done that. Most folks aren't aware they're even there.

Happily if it's oil it won't interfere with a forge weld. 

Frosty The Lucky.

[Purple Bullet]

Well, I THOUGHT I had a well-formed billet. Yesterday I started to heat it up and was treated to multiple geysers of smoke and flame coming out of my billet. I started heating back up to welding heat and was treated to the same kind of pyrotechnics you see doing a normal weld; a nice shower of sparks in response to my hammer's caress. Is this normal for a canister produced billet?

My billet is becoming much smaller than I thought so I changed coils to a smaller coil. I got the ends pretty well consolidated, but I found several severe cracks and broke the billet near the middle after a heat to try to consolidate. 

Here is what I think happened: First, obviously only the outside of the billet was welded. The inside was not. I don't think this is much of a problem because you can just reheat the billet and finish welding. However, when the geysers started, the smoke smelled very much like the smell from the fish hooks after I soaked them in paint remover, then burned off the excess. Perhaps not all the lacquer or varnish was removed. Secondly, I did not pack the hooks evenly. I started with adding powder and hooks, but when I saw that I would have hooks left over I tried to really pack them in. I may have created areas that the powder couldn't get into and left voids. Areas that had my initial pack solidified very well, while areas that had bunches of hooks cracked.

What's next? I'm thinking of breaking it up everywhere I see a crack, solidify each piece individually, put a long scarf on them and try to reweld them in the induction forge. I may also weld a piece of 1060 for the tang as my original billet is getting much smaller.

[ThomasPowers]

ISTR that high frequencies tend to travel along the outside of a conductor and  billets are known for being a but fussy transferring heat as they have gaps between pieces. (One way to find delams is the heat a billet and look for place tha heat isn't even.)

Could this be part of the issue?

[Purple Bullet]

Thomas - That's the way I initially found the delams. I called them cracks but I know that isn't technically correct.  If what you suggest is correct I would expect an almost uniform inner failure to aggregate. I'm sure you are correct about the way it heats. My understanding is that ALL electrical flow is on the outside of the conductor, so that would be the same for induced eddy currents as well. 

However, some areas were well consolidated and others weren't. It seems to me to correlate to the uneven packing job I did with the hooks. As we discussed earlier, ALL billets heat from the outside in.  The same heat transfer properties are at work. The difference is that induction heats SO FAST that, as you suggested, you have to make several heats to let the interior catch up with the exterior.

It took me a long time to learn how to weld in my coal forge. The mistake I kept making was cranking on my blower so hard I burned the outer steel before the inner was ready to weld. Since all you can see is the surface, that is what you judge by, but as we know, the whole welding area has to be at that temperature or close to it. On the induction forge the way i handle it is to come up to orange two or three times before going to white a couple of times.  I've convinced myself that the same would have happened no matter what kind of forge heated it.

Induction forges are kind of like computers in that they allow you to make mistakes MUCH faster.

[Frosty]

You may have to do a more thorough job of stripping the chrome from the hooks. Chrome isn't fond of forge welding to itself unless you get it REALLY hot. 

I'll have to do some reading about induction heating, I must not have the right handle on it. I understood it to be electric current generated IN the metal being heated by a high frequency alternating MAGNETIC field, NOT current being conducted through the metal. I understood the latter to be "resistance heating" as in an electric heating element.

Frosty The Lucky.

[Purple Bullet]

Thanks, Frosty - All of these hooks were either black or blue. I thought they were just HC steel; made to degrade fairly quickly in water if they are lost, but coated with some lacquer or varnish or something. I used 2 doses of paint stripper, that is, I covered the hooks with the clear solvent and stirred with a rod until the solvent was all milky, dumped and repeated. After the second washing and dumping of the solvent I lit it off with a torch to burn off any solvent that remained. I may not have done that well enough as I smelled that again when I started to heat the billet to draw it out.

As for the way induction works. I think it was in one of my NACE courses that the instructor told us that all electrical flow was along the surface of a conductor and that the advantage of larger conductors was increased surface area. While he seemed to know what he was talking about, it made me wonder "Why are large conductors not hollow?" You could save a lot of material costs with the same capacity.

I'm not an expert on induction at all, but I believe you are right in that it is high frequency reversal of polarity that causes a brief electrical flow one way, then the other. Its hard to think of electrons having momentum and maybe its just that the eddies are created as one wave passes as another is going the other way, but the electrons bump into each other, just like they do when too many are forced through too small an area (resistance heating). Like I said I'm no electrical engineer, but that's what it seems like is happening.

Frosty - I know you have (or had) a Little Giant so you must have 220 single phase. Get you one of these Chinese units. It's like going from using a typewriter to a computer. Heck, if this one ever goes down I may look into an Ameritherm unit. When you are as old as I am (70) you HAVE to make your mistakes quicker!

[Frosty]

Some of the larger transmission lines are hollow aluminum, or so I read back when. I'm talking Popular Mechanics or Science when I was living at home.

Frosty The Lucky.

 

 

[ThomasPowers]

Frosty; what do you get when you have a varrying magnetic field going through  conductor?  Oersted"s law in reverse!

[Purple Bullet]

Parents! If you want to indoctrinate your children with questionable values, send them to college. If you want them to get a EDUCATION have them read IFI.

[Frosty]

17 hours ago, ThomasPowers said:

Frosty; what do you get when you have a varrying magnetic field going through  conductor?  Oersted"s law in reverse!

Yes.

Frosty The Lucky.

[Purple Bullet]

And its Oesteads rather than Faraday's because Faraday's Induction law involves a common core, like a transformer. Although Oesteads only applies to DC, what is AC but DC that changes flow direction.

Interesting that according to Wikipedia, Faraday's findings were not accepted until Maxwell quantified them mathematically. I believe that's the same Maxwell that postulated Maxwell's Daemon., a thought experiment involving a gate operated by a daemon who would only open the gate for more active molecules. (That does seem like a hellish job) That is where the Daemon in a server gets its name. It is a small program that monitors network traffic until if finds something flagged for its server and lets it in.

[Purple Bullet]

An update on the induction forge canister Damascus: First the good news - on my third try I first heated the empty canister to a nice even dull red to make sure no coatings or oil was left on or in the canister. I used a small wire brush to clean out any residue. I then painted the inside with a white indoor/outdoor self-priming paint and let it dry overnight. The canister came off REAL EASY this time.

However, as I started to tap this into the rough shape I wanted, I started to get cracks. Most were up on the back edge of the knife and I typically add a copper or brass strip to the back edge before I heat treat so I kept going.  I brought it over to my 2X72 and tore into it with a #32 grit belt. It was barely removing any metal! At this point I began to get suspicious. I treated this as I did all my other knives. That is I heated to an even red and stuck it in the coke and dust in my coal forge to cool slow. When forging, I never let it get absolutely dark. One of the nice things about that induction unit is that as soon as the color starts to fade, you can pop it back in the coil for a few seconds and you are good to pound again. So my metal seems to be "red short" (Clue number two). Since the belt wasn't making much of an impression, I brought out the medium artillery, my 7" angle grinder. It would grind but the sparks look strange to me. Typically, I'm used to seeing a yellow spark with lots of "starburst" at the ends. This spark was fairly straight, and started off more orangy-red. This kind of reminded me of what the sparks look like coming off the cutting tool for my lathe when I grind it. High Speed Steel.

Usually, I make knives out of junk. I have a pretty good idea what the junk is made of, but there is always that uncertainty. For this job I ordered a five pound can of 1084 steel powder so I would KNOW I had good stuff.  Is it possible the can was mislabeled? I'm thinking of bringing a sample down to a gold dealer I've done business with and see if he will shoot it with his XRF analyzer.

[Purple Bullet]

OK, So I'm a noob. Spark test

[Frazer]

The type of grinding wheel and camera can make a big difference in how sparks appear. That being said, those certainly don't look like the sparks I would expect from 1084..

It seems unlikely the can would be mislabeled, but who knows.