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The Newbies Arena Are you new to knife making? Here is all the help you will need.

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  #31  
Old 09-01-2016, 09:42 AM
dtec1 dtec1 is offline
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thanks jim I just took a look and it seems prity good as far as the description goes I still don't know everything about the ingredients I do know stainless needs to have 10.5% chromium right? the 3-v has 7.5 but that's still enough to give it resistance to rust right. jim do you know anything about positive pressure quench (or any where I can get some info on it) ray had described it a lil but I cant remember the details (I tried to find the thread he explained it and couldn't find it) but I also don't think we talked about it in detail so I definitely need to get some more info on that as I was looking at a few different steels and a lot of them have this as a quench option and I would like to do testing on a couple different ways if I start using a new steel. I did some searching on positive pressure quenching and really could find much and nothing on how its actually accomplished.
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  #32  
Old 09-01-2016, 12:21 PM
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Ray Rogers Ray Rogers is offline
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I think I recorded a positive pressure quench for the hollow grind video but it isn't available yet.

Most pp quenches specify 2atm which means roughly 30 psi of moving air. more than that is OK and I generally used 60 to 80 psi. I have a 12" long piece of tin nailed to the side of the work bench next to the quench tank. The tin curls into a cylinder shape about 5" in diameter. The nails are in the middle of the tin and the edges curl forward forming a cylinder, the edges are not connected - they are left with about a half inch gap.

Interrupt the oil quench when the steel hits about 1000 F. This doesn't take long, only a few seconds after the oil stops boiling around the blade. Put the blade inside the tin cylinder (I hang it on a nail in there) and start spraying the high pressure air on the blade using the gap in the tin to work up and down the blade. Have the edge of the blade facing the gap because that is the most important part to be cooled. Continue with the air until the steel is just warm to the touch of your bare fingers, then let it cool to room temp, then cryo immediately.....


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  #33  
Old 09-01-2016, 02:11 PM
dtec1 dtec1 is offline
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thanks my air compressor should be fine for that then...when I attach the spray gun for the cera coat it has a gauge and I always have to turn it way down to get the air to 30psi so without that gauge on it deffinitly way above 30 psi. have you found the interrupted oil AND the positive pressure better tthan just one on some steel? I thought it was one or the other as most spec sheets I read said say P.P. quench to 125 or interrupted oil to 1000 then air cool but I guess if you do the interrupted oil then P.P, would cool faster than still air, this tin you have that curls in is it horizontal (kinda like how a forge would be) or is it vertical? then ends are left open? make sure you let me know when that hollow grinding video gets done! hollow grinding is probilly the thing I am worst at although I am getting a lil better VERY SLOWLY tho
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  #34  
Old 09-01-2016, 02:57 PM
jimmontg jimmontg is offline
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Dtech. To be considered a stainless steel it depends on how it is defined. The normal condition for cutlery steel is 13% chromium, so you can see why 440C at 17% is one of the highest in chromium content. D2 at 11% is practically stainless and even A2 at 5% has noticeable corrosion resistance. There is the free chromium content considered by metallurgists that the chrome content that is tied up as carbide doesn't help with corrosion resistance and in a high carbon steel 11.5% of free chromium is needed to to resist corrosion.
Now your 440C has Molybdenum which also is a carbide maker and also helps with corrosion resistance too. Doesn't matter to you or I really. Like I said we wouldn't ordinarily see much difference in corrosion resistance between 440C and 154CM, but the 154 is a superior steel to my way of thinking because it is. 440C is cheaper and you use cryo so go with the cheaper as the cryo can make up the difference for the final product. I have no problems with cryo'd 440C, it's great stuff. The cheap processed 440C is what gave it the bad name.

Last edited by jimmontg; 09-01-2016 at 03:02 PM.
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  #35  
Old 09-01-2016, 03:19 PM
jimmontg jimmontg is offline
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Yeah Ray has the Positive pressure down right. Just put it in an enclosed area and blow air on it. Problem come when it says hot air blast. LOL
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  #36  
Old 09-01-2016, 03:40 PM
jimmontg jimmontg is offline
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Oh, just as an aside. If you are air quenching a steel from high temp and you have a brass brush, try brushing the part while it is hot. The brass will come off all the way down to about 300 degrees and brass plate it. I used to brass plate my welds that way. Boss asked me why I made the parts out of brass once. I used to do it to O1 knives, but I had a big brush.
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  #37  
Old 09-01-2016, 04:13 PM
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The tin is vertical and the ends are open. Yes, the interrupted quench followed by pp gives noticeably better results on some steels like S30V. However, I wouldn't use that process unless the spec sheet suggests it.

I think you said you had some S35VN. You'll want that process for this steel if you want the best possible performance from it ...


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  #38  
Old 09-01-2016, 07:38 PM
dtec1 dtec1 is offline
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ray I lost you for s35vn you mean the best would be what your describing oil and P.P. or as the spec sheet says and one or the other?

jim I usually coat my blades to prevent decarb but if I wanted to put brass on it like you described obviously I wouldn't coat it but I have never not coated unles sometimes with a plate quench I use foil but if neither are used isn't some decarb formed and wouldn't you remove all the brass when grinding of the decarb??
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  #39  
Old 09-01-2016, 08:12 PM
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The best results I was able to get came from combining both as I described....


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  #40  
Old 09-01-2016, 08:31 PM
jimmontg jimmontg is offline
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We used argon gas in our oven so no decarb Dave. I was a TIG welder, Tungsten Inert Gas. I just hooked the oven up and filled it with -1 CFM of Argon. Only time we used foil was when somebody else did the HT, but I meant brush after temper during cool down. I sometimes welded with Helium for a much hotter weld like for thick aluminum as the plasma field around the electric arc would be much hotter than around Argon. It also changed the appearance of the weld. We used an old cook oven for tempering below 500 degrees that had a special thermometer in it for accuracy.
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  #41  
Old 09-02-2016, 04:41 AM
jimmontg jimmontg is offline
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Wink Just putting some trivia out there

I haven't done this,but it may be worth experimenting with. It will only work with alloys that heat treat under 1700 degrees F as that is the melting point of brass (copper,tin, zinc). Take, let's say a knife made from O1 and brass plate before HT. The brushing method is about a thousandth, 0.001 of an inch thick btw.
If you have the ability to electroplate the knife to 0.004 it may be interesting to see the resulting product. A controlled atmosphere kiln would be a prerequisite for the endeavor. I'm sure somebody has tried it, so I am sure it isn't a feasible financial deal. I was just pointing out that if you wanted your knife to appear golden you could wire brush it while it's hot after temper. You could of course just simply electroplate it after it was finished, but it cost money to have somebody do that.

BTW, FYI CO2 is not used for a controlled atmosphere oven as it has carbon in it. Don't be tempted because it's cheaper than Argon which isn't all that much higher and Helium is much more expensive. Helium is actually a byproduct of natural gas production. Once it is released into the atmosphere helium escapes into space never to be recovered again. All of our helium comes from the ground, there is precious little of it in our atmosphere and it is gone tomorrow.

I'm way overeducated for my station of life. I know enough about most things, but usually just enough to be dangerous. LOL

Last edited by jimmontg; 09-02-2016 at 05:03 AM. Reason: To make a humorous point
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  #42  
Old 09-02-2016, 09:56 AM
dtec1 dtec1 is offline
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thanks ray jim yes argon would do it. I did a lil research into it after ray told me he used it, deffinitly something I will look into more in the future but for now coatings and foil will have to do you have peaked my curiosity with the brass brush deffinitly going to try that
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  #43  
Old 09-02-2016, 04:57 PM
dtec1 dtec1 is offline
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ok so before this thread dies and since we are on the topic of steels and HT. is 1095 NOTICABLY better than 1084? I have a friend that saw the show forged in fire and now wants a blade with a hammon. so I have only done one hammon on1084 it ended up being higher up the blade than I liked but I figured ill give it another shot I have heard people progress from 1084 to 1095 but don't really know much about it I am going to write a email to njsteel and find out what manufacturer they use for there 1095 so then I can look up a spec sheet but I was wondering if it is even worth it...I mean if it is no better than 1084 then ill just use 1084 but if it is better then I deffinitly want to learn how to HT and use 1095
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  #44  
Old 09-02-2016, 05:42 PM
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Ray Rogers Ray Rogers is offline
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They are very similar steels but the additional alloying elements in 1095 means it needs a fast oil that most noobs don't have which is why we suggest they don't use 1095. You have the oil so go for it if you want. 1095 is very good steel, it takes a brighter finish that 1084 and will only etch to gray in FeCl unlike 1084 which can go to black. 1095 can show a very nice hamon BUT putting a hamon on 1095 runs a slightly higher risk of cracking the steel than with 1084. In any real world sense the actual functionality of a blade made with either steel will be very similar with 1095 having a slight advantage in hardness. In short, 1084 is less trouble but 1095 gets a little more shiny if you polish it ...


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  #45  
Old 09-02-2016, 05:44 PM
jimmontg jimmontg is offline
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Not enough to worry about in my opinion.

Making a Hamon is a kind of precise thing to do and yours being higher up wasn't because of it being 1084. I would think 1084 would be a little easier than 1095 as it won't be quite as touchy. The difference between the two steels is one of small degrees and end process hardness. 1095 can be harder and has a little different manganese content which helps with grain growth, but if you made an optimum knife out of either nobody could tell the difference.
What kind of clay did you use or did you just torch it Dave? Also you don't have to use ferric acid. Cider vinegar will do it too, just slower.

Last edited by jimmontg; 09-02-2016 at 06:09 PM.
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