Knife Making Log, Advanced Class 202: Steels

[Steve Sells]

steve sells
tonight we continue with the advanced class of series 200 by covering steel choices for pattern welded blades. Not all steels work together easily, some pull apart easily when cooling due to differing expansion and contractions rates. If you are just starting out please review the 100 series for getting started, this is for people that already know blade smithing, and want more we advise learning to forge weld before trying the pattern welding as many patterns place a lot of sress on the weld and if not 100% solid WILL pull apart
 
Steel choices
Using as simple as possible and still geting a usable blade means paying attention to alloy cpmtemt as well as carbon. if carbon is too low it will not harden. So a 1095 and 1005 mix will not result in a very good blade. due to carbon migration, in the forum I posted links to testing that shows it doen not take very long for carbon to migrate completely, so equal parts or 1095 and 1005 will result in about 1045, WHy ?> 50% is the simple math but you will lose some to atmosphere as well. Maybe more depending on how hoit you weld.  I perfer to use only steel that make good bldes by them selves, to limit theis problem of migration I suggest to start, 1084 or 1095 and 15N20.    15N20 is bascially like a 1075 with 2% nickel added and they heat and expand at the same rates, also welding temps are very close. as the nickel diesnot effect it much if at all work with simpler steels, same as when first learning blade work itself, to limi the possable problems you will enounter, adding in more challanges as you learn to use this.  Jumping all over with various mixes all the time is confusing for PW just as with basic forging, we need to allow a little time and wexperiance to gain the skills with one, then moving on is fairly easy,  One example of confusion is a recient post in the forum where a member just started and he choose a higher alloy for his first attempt at a good blade, he tried a differential quenching and had all sorts of problems, incluing cracking. I can guess, but He cant understand what when wrong, I feel that is because he addded too man new (to him ) things at the same time, so thererfore he does not know which new addition cause the problems.
 
If we slow down and only add ONE new item to our training schedule we can focus on that one new addition, becdause we were already cofortabel in that we were dpoing before, DOes this make sence ?? to limit new addiots to ONE ara time whe ever we can ? ok its not that I want to stop anyone from enjoying themselves, but as I said before I has seen people give up in frustration becaue of ocver load, I am mearly attempting to limit that, and help people grow, even if not doing blades, pattern welding can add many testures and colors to our work I didnt have the link handy because I just thoguht of it, but in our forum there is a wonderful Clock http://www.iforgeiron.com/topic/23797-pattern-welded-clock/?hl=clock a member made from pattern welded steels also bowls, and jewelry I have used scrap's form blades to make fishing luer's if they are too small for a bolster.

One thing we need to be aware of if a NON hardened steel will not look the same as when after the HT is done, the colors wash out until after hardening. I an not sure exaculy what happens to cause this, maybe Rich Hale knows, but I have seen it.  we can cover other HIGH alloy steel but I thiknk you get the point start sinple then as we progress in skill, add more things, CUrrrently one of my tacxher has ne working on his MAD 6 mix which is M2 A2 D2 in a coal forge.  I have not got it yet, be he says he does it and I can learn to, I now turn to floor over to Mr Hale.

Rich Hale
As this is another of our advanced sessions, I will offer another mix tha may interest some of you. Steve spoke of high carbons and low carbon stgeels, So let me talk about high carbon and no carbon he mentioned 15N20 as having a low percent of nickel and with that it provides great contrast to HC like 1095 It offers nothing but looks to a blade That said, I am putting a billet together with 1095 and pure nickel.I have done a lot of these. There is no carbon migration, The two do not weld but bond well.  A one inch strip of 1094 sttel .030 thickness it had some patina on it,,and i am nto going to use any flux at all in this weld. The surface has to be realy clean or it comes aapart The side I have started cleaning is nto clean enouigh in this pic.  I could have cleaned it with a soak in vinegar but was out, If I grind it on both sides there would nto be much left I used a sctchbrite belt to clean The nickel I am ujsing is .003 thick and is clean up front Here is the pile of clean parts Right at 50 pieces Now for youi withouit a hnand hammer think about that: At the completioon of a first weld with this mix I have a 50 layer billet I could just flatten it out and forge or grind a blade from it.  Or if I draw it three times its 8 inch length and stack and forge weld I will have about 150 layers, The way each of these metals expands and the thinness of them makes it not possible for me to tack on end together ,,wire in several places and forge weld to one solid block.  So we do first weld in a can  Nickeil will nto bond to itself The outer layers muxt be HC i cut some eighth inch mild steel bar stock for the can   I need to knwo how deep the can needs to be so I gather the pieces and get a rough measure of how tall the sides meed to be i cut a bottom out,  Two sides that will be right for the thickness,  And a top,,that will slide down in between the two sides Then time to weld  And if we do not remember histgory we are doomed to repeat it. The two sides on this are over an inch tall and welded to the botttom That will not work like it did not in my past. The sides have to be taller so I can put the lid on this loose stack and clamp it down Teh I can tack lid to sides and cut off the sides so I can weld along them to lid.   When I have have bottom welded to sides and before I stack layers in I can put some paper card stock in as first layer., I mentioned no Flux,, As the card stcok smolders in the forge it will usde up all oxygen in the can..There mus be no air leaks anywhere for this to work.  i clamp top on,,tgack trim sides, weld sides and lend caps on. We must know which way the layers are insdie the can...I weld ahandle on,,and the flat part is same as layers,,, We wlant to forge this down so the flat s get thinner Takes a while to get to welding heat,,,it has to be hot all the way through,,and in fack it will weld at less heat in a can than outgside a can weld with light taps,heat weld other side etc, When youreduce thick neww by about a third it should be one block inside It will all look same color when solid. The mild steel I used for can I did not clean millscale...it may still bond with the HC  It will all be ground off  Ok when we have this billet welded up: lets think about the carbon contgent with this mix of HC and No c metals WE have about 50 layers,,one more than half is Hc,,,1095 and the other nickel,,, HC is .030" thick Nickel is .oo3 My shop math says that we have about 90% HC that remains at 1095,,or a little less than one percent HC

 steve sells
I dont think rich mentions, but we use very thin sheets fo pure nuckel because it will tend to alloy witht eh surrounding steels and appear thinker. also careful about folding too much because of this issue.

Rich Hale
WE do not want to drolp over all content b elow about .60 Carbon,,we have not,,,If we layer in thicker nickel we could, if we draw this billet out to three times its length and cut intwo places and restack and weld the nickel will be about .001" thick,,,and amaizingly bright in the etch. This will make a bright solid blade that has all tha we wish in a blade.... Weh we do cut and restack and weld we will have three pieces, each of which has HC on the outside. WE do not need to make a can for this weld Tack one end, wire a couple of places and weld,,I use flux then Twenty mule team. You can pattern this billet however you wish,,,and ite marvelous, will b  If you are not up to thise high skill work put it offet up to speed and g  For heat treat just treat itg like 1095.

stuarthesmith
I did not understand the can part

Rich Hale
We are going to enclose all side of this stack of metals  We mentioned welding in a can in last weeks session..this is in addition We will take pics of this as it goes together for next week

steve sells
THis is an advanced class. if you got lost please read the 100 series to understand, be aware when using multiple billets of twisted bars, to shim between the billets with carbon steel because the nickel can not touch itself or there will be a void ruining your work,  One cool thing about using pure nickel sheets is we can chemically hot blue this for wild effect, because pure nickel wont take the bluing

 

additional reading see: http://www.iforgeiron.com/topic/9025-choosing-steel/
 

[metalmangeler]

I have been thinking about these last couple posts, and I am wondering a couple things. How fast is the carbon migrating to the lower carbon steel, or more to the point what is really being removed when we grind off the can? Would it be better to use high carbon to make the can and not remove? The other thing I am wondering is about using the pure nickel in the blade does this not leave some soft spots or are they so small that it is not noticed? Thank you Steve and Rich for taking your time to put this together for us. Mark

[Rich Hale]

You sure can use a HC steel for making a can,,i dont. And for sure the nickel is soft. i started out with .003" thick and about 50 layers total of both metals. I have forge welded the can to one third thinner than it started out. so roiughly after first weld  the nickel is about .002" thick. I will draw this out and cut restack and reweld,,how many times I do that will determine the thickness of the nickel in the blade....it is gonna be thin!

your concern is why I wrote that you must consider how much non carbon metals you include in the billet.

You can include more nickel or non HC steel and then weld on a HC edge also.

About that can: I did not grind the mill scale from the inside of the mild I used. I will find out soon but I do not think it will weld to the stack

I have heard a couple of theories abouthow much and when the carbon migrates in a billet. Keep in mind that it will not migrate through the nickel in this one. so everything  not touching the inside of the can will remain at the same as it was,,1095 and wherever in the range thatg use for the carbon content of this bar. if it did weld to the can it at that point will move some of the HC into the  mild, There is a thought that it moves fully after one to three welding sessions. In any case this will be a HC blade.