Why is CuMai Damascus so hard to forge weld?

[@solarstorm50]

Best explanation of forging CuMai I have heard

[@UKBladeshow]

Thank you Bob! I appreciate you taking time to comment! I hope you enjoy the rest of Graham's videos we have on the channel (amongst other makers we feature)!

[@TyrellKnifeworks]

I agree, do not melt the copper. I do this process all the time and after you get some practice, it’s easy to know the temps to keep it under from looking at it in the forge. I also would never advise trying to forge weld multiple pieces of steel as the core. While it may be possible, your chance of failure is extremely high. Just forge weld that first, THEN layer in the copper.

[@clarkeknives4159]

I totally agree. If you don't have the metallurgical understanding and correct control/monitoring equipment then the chances of failure in forge welding steel-to-steel layers together without melting the copper are high.

[@simonanstey]

Thanks. I know nothing about metal forging, but I know a bit more than I did 5 minutes ago. Knives, I love 'em.

[@UKBladeshow]

Hi Simon thanks for taking time to comment! If you enjoyed watching “about” forging, I’d suggest you check out this series we made on British bladesmiths: Makers Gonna Make - Joel Black Knives kzbin.info/aero/PLFssspwgISv8GPuCp4SMpQ2_BInVG-0SJ Let us know what you think!

[@simonanstey]

@@UKBladeshow Thanks so much! I bought one of Joe's knives some years back, a lovely damascus covered tool-steel (as he called it) santuko. Cheers.

[@TalRohan]

Not blade related I am still trying to meld copper and wrought iron, I can make it stick without too much trouble but making it stay together to finish what I am aiming for is a bit of a challenge....I have melted the copper which can look awesome in wrought iron but its no good for structure. I also found that getting wrought iron clean enough to stick didnt matter too much but getting it to stay stuck it has to be clean so I am presuming the copper migrating under scale is a factor...thanks for this, I may have a little more idea what I am trying to acheive now

[@UKBladeshow]

Hey mate you’re welcome! We’re very fortunate to have the likes of Graham helping the knife making community!

[@GemAppleTom]

Sounds like an interesting project. Mind me asking what you’re trying to do? It’ll cost an awful lot more but if you’re trying for a copper/silvery patterned mix then you could replace the iron with Nickel. You’ll avoid the problem of the iron and copper coming apart during working and Nickel can be wrought even more extensively than pure iron without cracking. (Though you’d definitely need to avoid melting - nickel and copper will completely mix together)

[@eddo7823]

Tyrell knifeworks said before that its more like brazing the copper to the steel than actually forge welding. Really interesting that melted copper can infiltrate and mess up the base steel if done improperly.

[@clarkeknives4159]

It's a nightmare and is, I think, the main reason why good quality Cu Mai billets are so expensive

[@ceceliahuynh]

This guy is awesome. More videos from him please 👍

[@UKBladeshow]

Thanks for watching with. Definitely have more videos with Graham in it so don’t forget to subscribe but please feel free to watch our other videos while you wait for Graham’s new stuff.

[@polisheverything1970]

Basically it's an aesthetic choice and not really a practical choice making CuMai, as usual Graham giving us the easy to understand and digest explanation/information.

[@HoutmeyersP]

Allmost all damascus knives made these day's are for aesthetics and allmost all knives are way to nicely finished for what their actual purpose is. Aesthetics is primarily the reason why a lot of knifemakers start. :)

[@vandelftcrafts2958]

Cu mai is so popular these days and understandably because it looks great. But it is not an easy material to work with. Great video!!

[@clarkeknives4159]

Thanks

[@_BLANK_BLANK]

This is good to know. Ive been doing experiments with high alloy steel cored cu mai. And i may change up the core material to something with a slightly lower austenizing temp. I think ill buy some d2 so i can run a test on that first. I dont want to waste a 80 usd piece of cpm 10v before i know what will work for sure.

[@UKBladeshow]

Hello again mate and thanks for watching! And you are correct, best to practice on a sacrificial, cheaper material than a CPM10V!

[@HoutmeyersP]

Copper to steel is fairly easy if you keep watching temperature closely. Try timascus/mokuti to steel.... now that what i call tricky. It works , but all the failures at first are very expensive. :)

[@UKBladeshow]

Hahaha thanks for your comment!

[@andyc750]

interesting, another few myths busted there that have come from established knife and video makers who obviously don't know as much as they think they do, was thinking of having a go at this, now I know I would be wasting my time as I am not anywhere near well enough equipped in the tool and forge department to try doing it so I will now give it a miss for the foreseeable future, cheers for this yet again, more valuable and interesting info for us all

[@UKBladeshow]

Hello Andy! Well, they are doable, but you just need special equipment to get the job done properly I suppose. Glad to see you enjoying Graham’s vids mate! Speak again soon!

[@bernardcaille]

Nice one from Graham once again.

[@clarkeknives4159]

Thanks Bernard 😊😊😊😊

[@UKBladeshow]

Thanks Bernard! Glad to hear you’re enjoying Graham’s series. Watch out for a handful more coming real soon 😉

[@JimIBobIJones]

Wouldn't this be affected by galvanic corrosion and be a terrible idea?

[@UKBladeshow]

Hi Jimi. Good question but I don’t think it can corrode in between the surfaces after it has been forge welded. As Graham explained, grain forms between the two substrates (and not to mention Graham also said there isn’t a “weld line” in between them) but we’ll see if Graham will see your query too. Thanks!

[@JimIBobIJones]

@@UKBladeshow It would still corrode from the surface and eat in further no? Galvanic corrosion is caused by electric contact between different metals. If you weld together two metals, you are forcing that contact. It's not a case of corrision where there is a gap between the metals. I guess you could put a layer of another metal that is less dissimilar than copper/steel to slow the process down but that doesn't remove the risk as there is no one metal is sufficiently similar enough with both metals to remove the risk. So you either keep it in a sterile environment and never use it or have a knife that will corrode if you let it come into contact with anything that could contain electrolytes (which could happen through contact with human skin, cutting anything organic like fruits, veg and meat or even moisture in a humid environment). Unless I am missing something in the forging process that insulates the two metals.

[@HoutmeyersP]

@@JimIBobIJones I have some cumai blades from a few years back.....non of them show galvanic corrosion. Maybe if the blades are used often in a salty moist environnement that could trigger galvanic corrosion since it also needs an electrolyte to start the proces?? What does happen is that the copper gets a darker red/brown color after time. I also did some cumai blades using layers of thin pure nickel foil to sandwish the copper layers in a stack with steel.....but then you could not call those cumai any longer.... Cunimascus , Nicumai perhaps :)

[@JimIBobIJones]

@@HoutmeyersP electrolytes are basically salts which can come from a lot of sources, ranging from minerals in your skin, cutting into meat/veg, dis.h soap etc. Galvanic corrision manifests as reddish rust so that could be it? Copper in its normal oxidisation goes green and forms a layer on top rather than corrodes the base metal. Not 100% sure how helpful nickel would be. It's galvanically similar enough to both most stainless steels and copper to be effective at slowing it down but carbon steels (depending on the composition) are generally in a different galvanic series than stainless steels so it's likely to be much less effective. Anyway, not a smith so have no real world experience of this but chemically it doesn't seem like a good idea (at least if you are selling them commercially).

[@UKBladeshow]

Great question really Jimi. I will speak with my friends in the metal industry (or better yet, I’ll ask Graham) about this. Thanks Jimi!