Critique my grain

[jmhallrn]

Hi all, I am very new to actually smithing but have been lurking here for the past few years. I finally got a forge and some 1095 (I have since sourced some 1084 that may be more forgiving) and took the plunge. I have forged a piece of 1/8" 1095 into more or less a blade shape and did a rudimentary quench in water (I do know oil is preferred, but I was really just experimenting). I promptly broke my blade about 10-15 seconds out of the quench trying to fix a slight warp. I had planned to test to destruction anyhow, so I'm not heart broken. I would however like to take the opportunity to learn about my grain. This was not normalized, the quench was done at only slightly above non-magnetic (much cooler a color than I expected), and it never made it to a tempering process. I have read quite a bit about grain but most of the photos on this and other sites that explained grain have been lost to time. To that end, please critique my grain...

 

The tip section

https://photos.app.goo.gl/6Wf4R62N7GvAYAGZ6

 

 

The rest of the blade

https://photos.app.goo.gl/eWPXzhV4PYNV1aV49

 

 

The "whole" (I guess not anymore) blade

https://photos.app.goo.gl/ZQrp88865vVf52eV6

 

 

Thanks,

Jared

[Frosty]

11 minutes ago, jmhallrn said:

(I do know oil is preferred, but I was really just experimenting)

The experiment was a success Jared, now you know why an oil quench is preferred.

You've got some grain growth, more than will survive a water quench for sure. Part 2 of the experiment explains why normalizing shouldn't be skipped. No?

I'm playing with you a little here but you put quite a bit of time into a blade then goofed off on the most critical part of the process. You deserve a verbal raspberry.

In all honesty Jared, why should a knowledgeable bladesmith (which I'm not) evaluate the grain in a blade you knowingly heat treated incorrectly? You didn't expect a smooth refined grain did you?

Frosty The Lucky.

[swedefiddle]

Good Mourning,

The School of Hard Knocks just taught you to not miss the Tempering stage. To try to take a bend out of a Hardened and unTempered trinket is foolhardy. I hope you have learned why the Best Time to Temper something, is IMMEDIATELY after the Hardening Process, no delay or lunch break.

A friend of mine was reworking a Ball Pein Hammer head. He Forged it to the shape he wanted and Hardened it. For some reason, he put it in a drawer in his workshop and forgot about it. He opened the drawer about a year later and found the Hammer Head he hadn't finished. The complete Hammer Head looked like a road map of any town, cracked itself to relieve the strain of the Hardening. He gave it to me and I use it when I am teaching a Blacksmith Class, as an example of the tension in a piece of Steel. 

Neil

[jmhallrn]

Frosty- You are correct in that I did not expect a smooth refined grain. My experiment here was to see what I am trying to avoid later. To my extremely untrained eye the grain was much smaller than I was expecting from something that was not normalized at all (although I suppose it did cool from forging to room temperature once as it was the second day). I am trying to learn exactly what you guys are seeing when you look at the grain. This particular blade had some deep hammer marks in areas that I found unacceptable and I felt it was a good piece to "test the limits" of how much pressure I can apply, what a water quench will do to the grain, etc. I intend to snap off an old worn out file tomorrow to compare them which I expect will give me some better understanding of what good grain looks like.  

 

I did see a helpful photo in in this thread which helps, but the lack of scale is making it hard for me to figure out where my photo would fit in. It looks to me like my grain appears in between the 1x and 2x normalizations in that photo. The factory heat treat appears to be almost as fine as drywall powder?

 

 

On a side note Frosty, I have read a lot of your posts over the past few years and I appreciate all the advice and knowledge you have unknowingly provided me.

 

 

Swedefiddle- That is an interesting anecdote. I never would have thought about a piece of steel that large cracking itself open.

[Frazer]

I'll make the same comment here as I did there, take a (through hardened) file, break it and take a look at the grain. That will at least give you a reference.

It's not my picture, but I think your 1-2x assessment is about right. The only trouble with assuming the grain you have now without normalizing and what you will have 5 knives from now will be the same is you may do more forging on the next one, you may get one hotter than than the previous one etc, etc. Unless you're making the same knife every time and your heat control is impeccable there is going to be variability in the forging process. When refining the grain you are trying to correct that variability with a definite, reasonably repeatable, process.

Just my, non-bladesmith 2c.

PS you can share your images by clicking the "choose files" hyperlink at the bottom of the editor. There's nothing wrong with sharing via Google images like you did. However, being selfish, it's easier to look at all three images in the same place rather than 3 separate links in different tabs and such. Not a big deal.

[Frosty]

If you wish to learn about grain growth then make test coupons and test for that specifically. Bring to forging temp and hold it for a couple minutes, quench an snap it. Keep notes and the marked coupon. Alter temp or time a given increment and repeat the test. 

Do the same test tweaked for hardening and once you know what temp you like to harden do it for tempering from coupons hardened at that temperature. 

Yes, a good heat treat should break with a soft gray surface without any sparkle. 

I can't see your breaks well enough to "judge" crystal growth."

Do you know why the larger the "grain" the more brittle?

I believe in the free exchange of information so I put what I know (think I know but that's a different discussion) out there. If it helps folks good, if someone shows me where I'm wrong that's more gooder! I sponge information from everybody I read.

Frosty The Lucky.

[jmhallrn]

Frazer- Thank you for the explanation and the photo from the other thread. Your comments on repeatability really struck home.

 

I seem to remember some older threads about limiting use of embedded photos due to limited bandwidth in some members' locations. And apparently photobucket stopped their free service since last I was active on any forums. I will try to remember for next time.

 

Frosty- I intend to do just what you have recommended, but I must admit that in my haste to begin learning (playing) with my new forge and steels (toys) I jumped almost straight into this blade with the understanding that it would likely turn out junk, anyhow. Once I proved myself right I just wanted to learn what I was looking at. As to your question, if I remember correctly the crystal growth has something to do with carbon and iron rearranging into various configurations that have varying strengths. I have read over the heat treating info from Mr. Sells but it has been a while.

 

Not to spend too much time on that different discussion, but I was just talking to my nephew Saturday about being able to honestly examine opposing viewpoints and reevaluate what you think you know. I personally feel that is a defining characteristic of an "adult", which means not many legal adults fit my criteria.

[Frazer]

Glad I could be of some help, though there are others here much more qualified to give advice on knives than I am. Regarding the photos, I'm likely just being lazy/picky. There's nothing wrong with a link. If you do choose to embed them in a post just double click the image and reduce the size to reduce bandwidth. Oh, the fun of computers .

11 hours ago, jmhallrn said:

in my haste to begin learning (playing) with my new forge and steels (toys)

I can relate

I think Frosty is referring to grain boundaries and slip planes. My basic understanding is that there are more grain boundaries in a structure with smaller, more uniformly sized crystals. As you bend the material you are temporarily (elastically) or permanently (plastically) deforming each crystal. I'm not going to go into what dislocations are* but basically once a dislocation reaches a grain boundary it has no where else to go. By increasing the amount of grain boundary you are limiting the ability for these dislocations travel which increases the strength of the material.

Each grain also has a particular plane where these dislocations like to move somewhat freely. This means it can be strong when force is applied in one direction, but weaker in another. If you imagine you have a vein of larger crystals that, on average, are oriented where these slip planes run part or all the way through your knife you now have a weakness where a crack can more easily form when force is applied in a certain direction. Smaller grains tend to be oriented more randomly which makes the material stronger in all directions.

This is certainly a simplified version of what's going on.

*If you're interested in looking at a 2D representation of dislocations and how they travel there is a cool video on youtube called "Experiments with the Bubble Model of Metal Structure 1952".

[Frosty]

13 hours ago, jmhallrn said:

I jumped almost straight into this blade

OH LORDY  NO!  Heh, heh, heh, that is so common it's almost a rite of passage. The only reason I didn't go that route is I got my first taste watching farriers and an old "Have Gun Will Travel" episode when I was maybe 9. 

Iron and carbon changing position in steel molecules is how steel hardens to put it silly simple. About my speed where the chemistry is concerned. The size and arrangement of crystals (grains) determines brittleness, hardness and brittleness are two different types of inflexibility. 

If you visualize a steel molecule as a group of iron atoms cemented together with a carbon atom, you're close to my limit of jargonless description. In it's mildest form steel molecules bond to each other without or maybe one carbon atom in the joint. at one point. Pure iron molecules aren't bonded rigidly, carbon holds a much harder rigid bond.

When cooled slowly enough the carbon and iron atoms have time to arrange their bonds in the least energetic configuration and with fewer bond sites the whole is its softest, most flexible and least elastic. It moves more easily and has the least spring back. 

Hardened steel molecules are crystalline and where they bond to the next crystal is a stress riser. A steel crystal is internally very strong and inflexible so any flex must be at the boundaries with touching molecules. Each joint has a LITTLE room to move and maintain bond strength.

So, the larger the crystals the larger the inflexible objects in the mass but maintain the same range of movement between crystals on fewer bond points. Hence the steel is becomes more brittle it's only "harder" in being harder to flex, compress, stretch, deform. 

So another simplified description goes like this. Visualize steel with 20 crystals per inch and each crystal joint has 1/1000 inch of flex before it breaks. Compare steel with 1,000 crystals per inch with 1/1000 inch of flex before failing. In the first case a 1" piece can move 1/500 before failing where the second case can move 1". 

This is a gross over simplification but the mental image can help deal with the reality at the anvil. Just like you don't have to understand fluidic physics to fly a plane but a handle on it helps.

Frosty The Lucky.

[jmhallrn]

5 hours ago, Frosty said:

Have Gun Will Travel

I see you are a man of good taste. Paladin would approve! In all seriousness, you and Frazer have just provided a wonderful explanation as to what the grain actually represents. Thank you! 

 

10 hours ago, Frazer said:

If you're interested in looking at a 2D representation of dislocations and how they travel there is a cool video on youtube called "Experiments with the Bubble Model of Metal Structure 1952".

Thank you! That was a great video. I did get some Young Frankenstein vibes at first, but the bubble model was a great way to visualize what you and Frosty were telling me. 

 

I did get a chance to break a file today to compare. The grain appeared almost velvety. I now have a couple of benchmarks and a much better understanding of what the grain actually represents. Thank you, both! When I finally get a knife worth showing I'll be sure to post it.