Eddie Mullins

Forge welding - number of welding heats for maximum strength

Recommended Posts

Thanks for that link, Eddie Mullins! He is one of the few that have addressed issues that I've been trying to discuss for quite some time. We discussed this a bit the other day on "blacksmithing enthusiasts" on Facebook. I believe it was Nath Oo that first brought it and related it to his experience of forging anchors and passing his tests.

Share this post


Link to post
Share on other sites

Deformation is a factor in welding; the more the weld is worked at high heat the better is usually becomes.

 

If you would like a technical reference for this may I commed "The Solid Phase Welding of Metals", Tylecote, to you.  It covers the reasons for what we know through experience.

Share this post


Link to post
Share on other sites

metal fatigue and cracking from vibration and flexing plays a huge part in the work I do. I have to up-set or draw down a long way to get the uniform strength I need. The average flower stem scroll work weld would just fall to pieces under load. Even simple things like bolt heads need to be bulletproof or a machine could be damaged beyond economic repair if they fail catastrophically.

Share this post


Link to post
Share on other sites

That video is great, it helped me a lot in learning what needed to be done.

Share this post


Link to post
Share on other sites

Thomas - that book is over $700 on Amazon. I may need to get freindly with the local Librarian...

 

His 2nd video I think is also very good one the forge welding process, fire management, etc. 

Share this post


Link to post
Share on other sites

Only US$185 on abebooks.com, with $11.23 shipping...  Wasn't that expensive when I originally bought it; under $50 as I recall.

 

But ILL at the local library should get it for you with no trouble.  Not a book for light pleasure reading...

 

hmm my allowance is building up again; must be time to buy another book...

Share this post


Link to post
Share on other sites

Thank you for sharing that.   I had been taught once is never enough for a forge weld, and to always repeat for a second welding course to make sure it is solid.   Now I see proof it is three, nice to know.

Share this post


Link to post
Share on other sites

Thanx Ed.. The video was great..  Maybe it will clear up for some that additional heats are often required... 

 

Forge on and make beautiful things

Jim

Share this post


Link to post
Share on other sites

When welding billets they automatically get more welding passes if you are folding and welding over and over.  I was always taught to do the last fold's weld twice as it was not getting the repetitive welding.

Share this post


Link to post
Share on other sites

Interesting video. I wonder if the extra homgenization of the weld is due to extra welding heats, or extra hammering (remember that stuff about peening arc welds you learnt at school?), or is it due to the "thermal cycling" implicit in this process? Might it not be the case that thermal cycling, appropriate for the alloy, which did not include bringing it up to as high as welding heat, would yield similar or better results. An electric welding manual would be a good place to start a study of post-weld treatment.

 

Whatever the case, always allow your welds to come as close to normalization as possible. Quenching them will do them very few favours.

Share this post


Link to post
Share on other sites

Interesting video. I wonder if the extra homgenization of the weld is due to extra welding heats, or extra hammering (remember that stuff about peening arc welds you learnt at school?), or is it due to the "thermal cycling" implicit in this process? Might it not be the case that thermal cycling, appropriate for the alloy, which did not include bringing it up to as high as welding heat, would yield similar or better results. An electric welding manual would be a good place to start a study of post-weld treatment.

 

Whatever the case, always allow your welds to come as close to normalization as possible. Quenching them will do them very few favours.

 

 There will be an element of all those things .

Time at heat is also a really important factor in all this to allow the material to be in contact at high temp post welding.

 

stretching the weld boundary surface area as well ,to allow non contaminated fresh material to move across the weld boundry and break up any contaminates (oxide , borax etc)

 

 thermo cycling to allow grain growth across the weld boundary .

 

A lot of this is pretty standard in the blade (damascus) world.

 

 It is worth keeping in mind that just like with regular welding there are times when all this matters ( insurance rated stuff and stress bearing members) and times when this does not matter and getting a quick job done quick is more important.

 In the same way that you would only use a coded welder for some tasks and be happy to weld some yourself.

Share this post


Link to post
Share on other sites

I have heard a blacksmith state that when he was educated about forge welding that a single faggot or lap welded area has approximately 7% of the shear strength of the original strength of the material.

 

it could be completely wrong but it seems possible.

 

Welding of any sort is typically not very strong in Shear strength in comparison to its Tensile strength.

 

Many of the old British anvils have problem's with the faces cracking off after a 100 years of use. (Better call the manufacturer)

 Simply butting two giant faces up and forge welding the face on to a large anvil seems like it would be likely to trap silicon and other unweldable materials underneath the face and it would take a massive amount of force to push it all out in a single blow.

 

In many cases this was done by hand so the quality of the welding was determined by the smiths, but even then if you welded on 50 faces a day by hand they all aren't going to be perfect.

 

Wherever there is a flaw in any weld it becomes the point in which everything fails. 

 

Which would also make great sense of why people used extremely high layer blades to improve blade strength,

 

the reason being to geometrically move all of the welds into more favorable positions and to homogenize the material while removing flaws

Share this post


Link to post
Share on other sites

Thanks for all of the great feedback. I see I have much more learning to do. It seems the more I learn, the less I realize I know LOL.

 

Forge welding is still a hit and miss proposition for me, I know I need more time spent practicing, but I also seem to find additional little hints and improvements as I study and ask more. Perhaps another thread might be in order for gerenal forge welding tips ...

Share this post


Link to post
Share on other sites

Actually in general they didn't  most of the world used fairly low layer counts when they were making swords for use.  Japan is one of the few examples where they often went for fairly large layer counts as they were: A. still starting with bloomery material and B. using the repeated folding and welding to drop the carbon content of the material---often from nearly 2% down to 0.5%

 

Most of the world dropped pattern welding swords as soon as they got better steels and just took it up again fairly recently (for my warped values of "recent") as ornamental weaponry.  The exception to this of course were damascus gun barrels and even that became an ornamental option in the 1930's (The Hunting and Fishing Museum in Munich, Germany, has a number of very nice guns with beautifully patterned barrels done duing the 30's and 40's.)

Share this post


Link to post
Share on other sites

Saw this video awhile back and repeated the experiments with the same results. I can say it dramatically improved my structural welds. I'll still single pass on some decorative welds, but anything that is going to take any stress gets a minimum of 3 passes.

Share this post


Link to post
Share on other sites

I've done a lot of lap welding over the years, and I nearly always take multiple heats. I've taken a half dozen or more welding heats on the same area making sure that none of them were sparking heats. I think my habit is to take the initial welding heat as a non sparking heat, what I call a sweating heat. Many times I will lose my welding heat after just a few licks, especially when welding small material. When this happens, the pieces may be mated properly, but the shuts are showing and the scarf points haven't blended yet. This requires more welding heats. I try to get rid of the shuts. If they are perverse, I use light, rapid blows on them at a welding heat.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.