VaughnT Posted March 18, 2014 Share Posted March 18, 2014 Is such a thing even possible? I have been working on a blade that got a couple huge mule tracks in it from my carelessness. Well, I've been pondering what to do with this blade ever since. Between further hammering and some quality time at the grinder, she'll be too thin for the length and width. So what to do with her? One of those proverbial lightbulb moments last night, I thought about doing a traditional San Mai construction. Not only would it save the blade, but it would look cool, too. The problem with that idea is that I'm still learning about this propane forge of mine and it just doesn't want to get hot enough to forge-weld in. Looks like I'll need to crank up the gas to at least 25psi to do that, and it's mighty oxidizing as is. Then it hit me..... what about just adding some beads of 7018 with my stick welder? The mule tracks are at the top of the blade near the spine, well away from the edge. If I pound the blade out a bit more, making it too thin for what I want, then lay down two beads of rod along the spine on both sides. Back into the forge to bring it all to heat for a bit of hammering to consolidate the whole shebang, and then to the grinder. What am I missing? Surely there's some problem I'm not seeing?! Would the beads show up with a nice contrast after etching? Would I be able to heat-treat the blade like any other san mai blade? Would the welding do weird things to the grain structure or something? Basically, all I'm really wanting is to experiment with this blade. It's small, and made from free stock (golf cart spring), so I don't have anything really invested in it except for the my time and propane. If this is at least a little bit feasible, I wouldn't mind giving it a go just so I could say I did it. But I can't help but feel there's a catch I'm not seeing. Quote Link to comment Share on other sites More sharing options...
SoCal Dave Posted March 18, 2014 Share Posted March 18, 2014 Give it a try, but I would think the 7018 is of different type of steel/material than the blade and would heat treat at a different temp than the blade steel. There are some very knowledgeable welders on this site that will know exactly what will happen. To get the 7018 to join with the blade, it will have to penetrate the blade enough and it will warp the blade. A good idea but I'm not sure if it would work out as you may hope. Good luck. Quote Link to comment Share on other sites More sharing options...
VaughnT Posted March 18, 2014 Author Share Posted March 18, 2014 San Mai is all about joining different metals. You want that difference in the metals to give you a contrast between the high-carbon cutting edge and the softer, decorative cheeks. If you can join wrought iron to 1084, you should be able to lay a bead on with the right rod. Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 18, 2014 Share Posted March 18, 2014 No problem laying 7018 beads nor heat treating. It isn't going to harden, it's low carbon with a good incident of rebound so may be a good blade material. What the hey, let us know how it works. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
jmccustomknives Posted March 19, 2014 Share Posted March 19, 2014 If you've got the time and inclination, give it a go. In my estimation, when you try tor forge the bead down it will cause an even uglier inclusion. Not to mention stress fractures from welding thin material. Finish it out in all it ugly glory and call it a learning experience. Quote Link to comment Share on other sites More sharing options...
Frank Turley Posted March 19, 2014 Share Posted March 19, 2014 Speaking as a smith, not a metallurgist, when forge welding, there is no molten puddle. The metal remains in a solid state and is eminently forgeable after welding. It remains pretty much like the parent stock you started with. With gas and electric welding, as the puddle freezes, you obtain a dendritic structure in the steel, different than the parent stock. When heated and forged, it does not always hang together like a forge weld. It is liable to crack. It may not separate or crack, but if it doesn't, you "lucked out like Perry Mason." As blacksmiths, one reason we learn to forge weld in the 21st Century is because the weld is forgeable. Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted March 19, 2014 Share Posted March 19, 2014 When you forge the welded up piece after to smooth things out..you will need to get it pretty hot...when you do that if you reach forge welding temps there will be carbon migration that will make the same amount of carbon throughout the piece...Youi can do a rouigh guess of the final carbon content simply by knowing the percentages of each kind of metal and the carbon content of each..the weld will start at less than 2 pts..and a rough guess will be that it will consist of over half the total steel..so if you use, lets guess 1084 at roughly 9 pts. 11 divided by 2 will be 5 1/2 pts....05 C To me that is on the low end of wot it takes for a blade...If youi are using a steel for the blade with less than 9 pts. Then the total will be less... For me when a bad thing happens to a blade I have learned to toss it and start over to assure a outcome I wish. Let us know how it works ouit. Quote Link to comment Share on other sites More sharing options...
VaughnT Posted March 19, 2014 Author Share Posted March 19, 2014 I figured there was something I was missing. If I could have thought of it, there's no reason smiths before me wouldn't have considered it.... and we would be seeing such construction being used today. I'll forge it out to see if I can save the blade. I have some wrought iron that might look halfway decent on the cheeks, but it's going to be awhile before I can get my forge to welding temps. That's why I was trying to not go that route. Quote Link to comment Share on other sites More sharing options...
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