Last words of advice before I start ruining some 15n20/1080 trying to make San Mai?

I'm just putting this out there into the ether, you can dry weld (no flux or kerosene) this without having to weld 360° around every layer. It's all on your forges atmosphere, run rich and your not making scale between the layers. Pull the bar out and quickly set your weld. Never done it by hand this way as I have a press but as the steel cools in the air it will create scale on the layers. So this being said I have never tried the kerosene method but can see a simaler problem in that the word on the street is the carbon layer is fragile. To me this means once you set a weld you better weld it all because your hammer blows just busted up the carbon jacket. This is assuming the carbon jacket is just shealding the steel from the oxygen and not doing anything else, I have my thoughts on this which I have expressed befor.

But onto something useful that you can use. I would say that if this is your first welding experience then use borax, it's how most of us all learned. It really does build in a good amount of forgiveness into the process. No need to go crazy with the borax just a lite coating so you can see it bubbling between the layers. Start at one end in the middle and gently tap, no need to go crazy on setting welds. In fact doing that will actually prevent the steel from welding. About all that is needed is the weight of gravity pulling the hammer to the steel. Give it a little more then that but not much. About as hard as you would start a nail in a board while holding the nail. Takes practis but that's half the fun. So start at one end and work to the sides and then down the length. Your trying to squish out all the flux and not trap any between the layers. Another thing you might consider is a vise. A vise can set welds as well as long as you can close it rather quick befor the steel cools off to much. I have used my post vise to set welds but I think any bench vise that closes square with smooth jaws would work. You can work the bar through the vise at an angle so the bar will clear the main screw. If this line represents your vise jaws ____ then the bar would look like this //. So looking at the front of your vise it would look like this __ //__. Start at the corner and work your way down the bar towards the rebar end.

Make sure your steel is hot enough but not to hot. You can tell that it's to hot when the flux is no longer liquid and just drys up and is hard and crunchy. The bar should be fuming when removed from the forge, aka smoke like stuff rising off the bars. The flux needs to be smooth and runny and bubbling vigorously between the layers. Lots of people say it looks like melted honey or butter. Also when the weld is set the liquid flux should come shooting out if using a hammer or you will see it run out of the layers if pressing it. A neat trick to testing the weld temp is using a coat hanger. Straighten out a coat hanger and bend the end over at 90°. When you think your billet is ready to weld stick your coat hanger in the forge, bent side in the forge. Pull it out and flux it and back in the forge. Let it heat to the color of the billet and touch the billet. If it try's to stick then it's ready to weld. Be cautious though as I had a coat hanger straight up weld to the billet when I touched the bar and it would not come off. This only happened once but it was entertaining to try and wrestle this limp coat hanger off the billet.

I think that's all the advise I got for now, just remember to have fun.
 
I welded up the billet(or at least I think I did) about 4hrs before your post JT lol. Thanks for your post anyway though, I appreciate it! BTW the 15n20 came in and looks good.

Like I said, I worked on the billet last night and think I did an okay job. That being said, I could have screwed it up in any number of ways and not even be aware of it lol. I did take some pictures though. I soaked it in kerosene for a few while the forge was coming up to temp and then stuck it in. I didn't move it at all until I brought it out to set the weld. I brought it out and hammered quickly with medium-light blows until it dropped below working temp. I stuck it back in and brought it back up to working temp and did this again. Probably 4-5 heats. Now this is where I might have screwed up because in my head I was thinking of the things I read "set the weld all in one go after fluxing with kerosene," and "flux with kerosene and set as much as possible in the first heat, then flux with borax on following heats." I didn't flux with borax though. So who the hell know, it could be scrapped, maybe not. Either way it was a learning experience. Next time I will do a dry weld/have it welded all the way around.

I cleaned it up but some of the weld is still on the sides, which will show in the pics. The parts where the lines between the pieces don't show is where there's still some tig weld left on it. I think I'll cut out a small kiridashi later tonight and see how things turned out.

How do you guys test/examine the welds on your billets? Some of the billets I've bought look like they either soaked them in etchant or ran some across the sides to illustrate the layers. Would it be okay to rub some ferric chloride alone the sides to see how it looks?

Are the lines between the pieces supposed to be visible, or is that delamination?

The billet was .305 before forging/welding and it's .250 after forging/welding and surface grinding.







 
That looks like delam to me. You can try rewelding with a borax flux, but those dark lines are almost assuredly oxide which will prevent you from rewelding it without flux. You can also just try to grind deeper into the billet. It is possible you just missed a bit of the edges. My guess though is that it will take a reweld with some borax flux. No biggie.
 
joedhiggins said:
That looks like delam to me. You can try rewelding with a borax flux, but those dark lines are almost assuredly oxide which will prevent you from rewelding it without flux. You can also just try to grind deeper into the billet. It is possible you just missed a bit of the edges. My guess though is that it will take a reweld with some borax flux. No biggie.
Click to expand...

I think you're right. I cut a small kiridashi out of the billet and on the inside of the billet it looks like one solid piece of steel.
 
You should not see any "line" so to speak when grinding the edges. You will see the layers when grinding but it's more of a steel color difference not a line where the weld is. Looking at your pictures above that's not welded, perhaps it's welded further in but until you cut into it you won't know. Another way to test is grind like you did and then soak in feric chloride. Then remove the steel and just wipe the surface gently. And non welded area will still be holding the acid and when left to sit will make a rust line. Let's see the inside of that billet.
 
Keep grinding, it's not unusual to have some bad area on the sides of welds that aren't done in a "can" type dry weld setup.

If you look at your own pictures, you can clearly see where the line disappears in some sections, that's what it looks like when you're into the welded area. You did fine.
 
In his pictures where the line disappears is where the billet was tack welded together. Waiting for a pic of the knife he profiled out of this billet.
 
JTknives said:
In his pictures where the line disappears is where the billet was tack welded together. Waiting for a pic of the knife he profiled out of this billet.
Click to expand...

Oh yeah, you're right I forgot about those long tacks. Either way, he very well may have solid welds in the center.

With san mai it's usually brutally apparent when you've got bad welds, even rough grinding the bevels, as it'll show a black line at the transition.
 
Yeah I hope he has a good weld, noting like a success at your first weld to get you good and hooked lol
 
Here some pics of the inside of the billet. It's exactly how a couple of you said. A little delamination about 1/4in from the edges and the inside looks like one solid piece.
















Could I just flux with borax and set the weld again on the outside? Would I just heat up to welding temp and then sprinkle on borax and let it sit, then brush it off? Then bring back up to welding temp(2300 ish) and tap the weld closed on the outside?

I've searched all over for "how to flux with borax" and found no specific instructions as far as temp and process.
 
Heat it to the bright red/orange range, sprinkle flux along the seams, reheat to forge welding temp. Light taps to start off, then heavier blows on subsequent heats. It may work. Borax will help remove the oxidation layer between the pieces, but there are no guarantees.

For future welds, if you have a flux resistant/immune forge (Bubble alumina lined in a gas forge, or coal), I find that borax on initial welds is the most consistent way, and saves you a lot of time welding the entire billet up, and has the added advantage of requiring little grinder work to clean the edges afterword.
 
I would have to object on fluxing the welds being easyer. Don't get me wrong I was a flux man but after being show the light I only use it for setting the very edges after the billet is all welded dry. I don't weld along the entire billet with a welder. I just tack the layers together. Heat in a fuel rich forge and once hot I press and done. Never failed me yet and the great thing is no chance of trapping flux in the weld.

If your billet is good on the inside then your golden. Only thing I would do different next time is after you dry weld go back and reheat and sprinkle some flux on around the edges and then put back in the forge and let it bubble and clean out the scale. Then remove from the forge and gently tap around the edge. This should give you a solid weld right to the edge.
 
You'll lose less on the edges with practice, but I doubt you'll be able to fix the edges on the current billet.
 
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