Hello,
I'm looking for input on something. Recently I forged a couple stainless clad laminate billets. I haven't done many of these, maybe a dozen +, but have had good results after a couple initial failures to weld.
These particular billets are 416 stainless cladding, pure nickel, and 52100 core. This is the first time I've incorporated nickel into a stainless clad billet.
Both billets went fine, but upon finishing the blades and going to the ferric etch, I began seeing an interesting phenomenon on one of the blades. It appears as some light, "wiskery" deposits of nickel on the core steel. This only showed up when put in the etch, and dissapeared from sight when re-sanded with the 1500 grit paper. Back in the etch, and it appeared again. At first I thought maybe I wasn't cleaning frequently enough, but I don't think that was it. I was etching both blades at a time, suspended on the same rod, and thought maybe some sort of electrolysis was taking place. I re-finish-ground the blade, which did not fix it.
I decided the most likely reason was I had overheated the billet somewhat and the core steel began opening up (maybe stating to melt at the grain boundaries..?!?) to accept or bond with the nickel beyond a regular forge weld. Additionally, the nickel layer boundary is not crisp, which also seems to indicate overheating.
Whatever the case, I decided to discard the blade and do some heavy testing to destruction to see how the steel held up. I was pleasantly suprised, and did not notice any issues with the steel at all. I finished up by snapping the blade twice, and even though it had been tempered of course, I got a pretty good idea of the grain size and it looked good. (on the 52100; the 416 looked a lot worse actually).
I've included photos of the snapped blade, the nickel deposits, and the knife that turned out properly.
I'm wondering if anyone else has experienced or seen something like this?
Thanks,
Elijah
Photo of "nickel deposit"
Curious. I've made a ton of stainless clad San-Mai since about '08.I've never seen the stainless look like that.
Which part do you mean specifically? The outer stainless cladding, or the nickel layer between that and the core?
What grit is the steel in that last pic sanded to? It looks really coarse. Do you have a pic of what it looks like at say, 400 grit?
“So I'm lightin' out for the territory, ahead of the scared and the weak and the mean spirited, because Aunt Sally is fixin’ to adopt me and civilize me, and I can't stand it. I've been there before.”
Also, what temp are you welding at?
“So I'm lightin' out for the territory, ahead of the scared and the weak and the mean spirited, because Aunt Sally is fixin’ to adopt me and civilize me, and I can't stand it. I've been there before.”
Hello Elijah,
I might be wrong, but: There is a process of non-electric galvanization (I don't know how to call it). In this process, the phenomenon of displacement of "more noble" (less electronegative) metals from the solution by "less noble" (more electronegative) metals is used. In the case of copper plating of iron or steel objects, immersed in a solution of copper salts, e.g. copper sulfate, a copper coating (less electronegative, more noble metal) is deposited on the surface of iron or steel (less noble, more electronegative metal).
Because nickel is less reactive than the iron I, assume that the reaction that happens in your case, was exactly the same as described above. Stainless steel on the other hand is much less reactive than the nickel so it explain why the layer of nickel was plated only on the core.
The last pic is of the blade after I went back and finish ground it again. I don't have a photo when it's sanded up to a high grit, but the nickel deposit or whatever looked the same.
Galvanic effects and such things are quite interesting, I don't know much on those subjects.
Joshua I don't know for sure what temp I'm welding at. I suppose I could install a PID and take some of the guesswork out. I've just gone by color of the steel and experience so far.
I was referring to the stainless jacket really grainy appearance.
Mine looks like: [img] 
[/img]
I see, yeah the other 416 stainless cladding I did was similar with the appearance, I figured it was due to the sulfur content. 304 stainless cladding I've done is clear like your blade.
My blade in the photo is 416.
Hmm, interesting. Do you use any kind of outer layer to protect the 416 from atmosphere?
