Prevent Explosive or Magnetic Pulse Welding/Bonding

[vigildesign]

A new issue has come up and I am looking for some information. For anyone using explosive welding or magnetic pulse welding: We are trying to prevent the welding from occuring. The welding/bonding is not what we are trying to do, it is a side effect. What are the things to avoid in using these methods when you are attempting them? We would like to implement any design or features that negatively affect Explosive Welding and/or Magnetic Pulse Welding. Energy release is about 3-4 megajoules. Material is 304L on 304L.

 

[CoryPad]

How about inserting a ceramic between the metal surfaces?

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[btrueblood]

Same thought as CoryPad, but use a ceramic-containing spray, such as Boron Nitride, a flexible ceramic/glass blanket (woven fiber) or an anti-galling compound (Moly Disulfide containing) in a grease or similar binder.

You don't say if the parts are going to be deforming as a result of the blast (i.e. are you explosively forming parts?) or not. A rigid ceramic or fused/deposited ceramic/cermet might not survive well enough to maintain seperation, powders, fibers or a powder/binder mix might.

 

[metengr]

vigildesign;
Just curious, what exactly are you trying to do? The reason I am asking is that the the methods you mentioned above that you are trying to avoid are for joining purposes, which is not a side effect.

 

[unclesyd]

As stated above what is the end result needed?
Nearly everyone else is concerned with getting better bonding.

The contact forces between the two processes have two entirely different physical parameters. The main one being that the explosion bonding is wave applied force while the magnetic pulse is a wide area applied force. Another is the standoff distance which I understand in bonding some materials is very critical.

I have seen many inclusions trapped at the interface of explosion bonded plate, which tells me that a stop off or mask will have to be fairly substantial to prevent all bonding by this process. In a video (movie) of the explosion bonding process I saw no particular preparation of the plate interfaces other than general cleaning.

The only MP interface I've seen was an Al/Cu and it appeared that both metals were initially very clean prior to bonding.

For explosive welding/bonding there is a lot literature available. You may have to go data mining to find a
solution to your problem.

Here is one lead for information on explosive welding.

http://www.dynamicmaterials.com/Div...s and References/Explosion Welding Technology

 

[vigildesign]

We are seeing many new issues on this new $90M Pulsed Power Machine. We may have solved the welding/bonding issue by making multiple cuts to weaken the parts so they do not deform, but rather shear apart. I have looked at many publications and websites regarding how to do the welding/bonding process, but I would like to get more information on how NOT to do the process. Maybe something from people who may be using the processes and what to avoid. I have seen many places where the actual welding/bonding process is proprietary, but I am seeking the information from the failures, or failed attempts.

 

[unclesyd]

Looking at some old notes on using the Boron Nitride as mentioned above to solve some friction welding problems I concur with the suggestion of using same for your problem.

I would give the folks at ZYP Coatings a call. Over the years I've found them to be quite helpful.

http://www.zypcoatings.com/index.htm