1095 Oil and Water

We also have to consider the geometry of the blade such as a saber grind, where the primary bevel to take approximately half way up the blade, and a full taper to the spine. The shorter bevel on the saber grind causes courser angle where the bevel begins and a much larger difference in the mass of the top of the blade the the beveled area. This presents problems in some areas and advantages in others. One of the problems caused is the stresses applied to the blade due to the difference in the rate of cooling between the two areas. If you have ever seen the YouTube video of a Japanese sword master quench a blade in water you would be surprised that any blade survives that process let alone have only about a 25% failure rate.

So this leaves two choices. Read a rosery, light candles, plunge the steel in water and hope for the best or see if there is another quechant that is almost as good that will produce a little less shock. Or possibly grind the blade with a different geometry to reduce the stresses while cooling. You will find that blade making is just chock full of trade-offs. To gain something at one point you have to give up something else at another point. It is an art of ballance and compromise. Have fun.

Doug
 
Has anyone ever had a flat piece of > 1/8" barstock crack during a quench in anything? Probably not. It stands to reason that a blade that most closley mimics barstock with the largest area of "flat" would be the least likely to crack during the quench.
 
I've seen it on a bar of 1084 1"x1/4". I believe it had .86% carbon, but a fair bit more manganese than the link material. Anyway it was just a thermal cycling demo. Two samples water quenched with visible differences in the appearance of the grain. Anyway, though the crack had to be completed, the bar was clearly cracked coming out of the quench. I truly don't think it means anything, but I would think it's possible to develop a crack during the quench of stock with a rectangular cross section.

Again, just one little snapshot, not gospel, Craig
 
The more extreem the variation in the shape or thickness the more likely it is that you will have problems with cracking during a quench but I would agree with Craig that a regular shape is not guarantee that you woun't have problems. I've had flat grinds crack in oil. One in particular that I remember. I had to take it back up to an austinizing heat to take a warp out of the blade after I had put a course edge on it. I really don't think that it was cracked going into the warm peanut oil but it sure was cracked when it come out. All the effort to salvage the blade and, bingo, it gets added to a drawer full of knife shaped paper weights.

Doug
 
Doug Lester said:
The more extreem the variation in the shape or thickness the more likely it is that you will have problems with cracking during a quench but I would agree with Craig that a regular shape is not guarantee that you woun't have problems. I've had flat grinds crack in oil. One in particular that I remember. I had to take it back up to an austinizing heat to take a warp out of the blade after I had put a course edge on it. I really don't think that it was cracked going into the warm peanut oil but it sure was cracked when it come out. All the effort to salvage the blade and, bingo, it gets added to a drawer full of knife shaped paper weights.

Doug
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There are very few absolutes in heat treating and even fewer guarantees. There are some simple things (discussed above) that can be done to greatly reduce the ping factor. Thus far, I have not had a slab sided 1095 3/16 or 1/8 blade "ping" going into water for a full quench at 1500 followed immediately by tempering at 400 - these blades were saber beveled, very gradual bevel to edge ricasso transition, no sharp angles and finished at 120 grit.

When you quench a flat or hollow ground > 3/16 1095 blade in water you are essentially quenching an 1/8" blade and that is where things get dicey between 1095 and water. 1/8 stock appears to represent the edge of the 1095 water quench envelope.

Also, there is a considerable amount of talk about 1095 and the importance of reducing the temperature of the steel as rapidly as possible. If this talk has merit, and I believe it does; then nothing does the job better than water or salt water.

1095 1/8 after uninterrupted water quench and before temper - 64.6 at the tip and 62.2 at midsection (no cracks, pings, dings, warpage , fractures...)
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1095 3/16 after uninterrupted water quench and before temper - 63.8 at the tip and 61.2 at midsection (no cracks, pings, dings,warpage, fractures...)
IMG_1894.JPG
 
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Six more 3/16 1095 at 1500 degrees quenched in water today - no warping, cracks, pings, dings or distortion. Also quenched two 5/32 blades - no problems whatsoever. All blades were saber beveled to .04 before heat treat.
 
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Six more 3/16 1095 at 1500 degrees quenched in water today - no warping, cracks, pings, dings or distortion. - no problems whatsoever. All blades were saber beveled to .04 before heat treat.
 
Six more 3/16 1095 at 1500 degrees quenched in water today - no warping, cracks, pings, dings or distortion. - no problems whatsoever. All blades were saber beveled to .04 before heat treat.

I suspect I would have the same results with a "balanced" convex bevel. Stay tuned...
 
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I buddy of mine had some 3/16ths 1095 blades Rockwell tested at 62-64 spine to edge, quenched in canola... without agitation. He did get slightly higher readings along the edge, but nothing drastic. A point or 2 at the most.

I suspect maybe some variance in carbon content from batch to batch, etc.
 
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Tai,

Thanks for commenting. You bring up a good point. There are many variables, only some of which we have any control over.

Jeff

ps ALL QUENCHANTS ARE GREAT
 
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I just heat treated 1095 with a brine quench today. 14 blades ranging from 1/8" thick to 3/8" thick. No pinging and the only one to warp slightly was the only double bevel in the group. All the single bevels came out straight, perfect and harder than a hookers heart.
 
Thanks for your report of an anomaly. Bravo...you might be onto something! What kind of Rockwell numbers are you coming up with? Sounds like you defied several laws of thermodynamics, heat transfer, physics and intuitive thought. See you in Stockholm!

I had six more 3/16 1095 at 1500 degrees quenched in water today - no warping, cracks, pings, dings or distortion. - no problems whatsoever. All blades were saber beveled to .04 before heat treat. They are not "perfect" and I don't know if they are harder than a hooker's heart or not...I had trouble digging up Rockwell hardness data of the internal organs of prostitutes.

Jeff


Jericoh said:
I just heat treated 1095 with a brine quench today. 14 blades ranging from 1/8" thick to 3/8" thick. No pinging and the only one to warp slightly was the only double bevel in the group. All the single bevels came out straight, perfect and harder than a hookers heart.
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correct me if I am wrong.... but I thought the forge scale was super hard and would give a false reading unless it was ground off prior to testing.

ernie
 
Valid point, you are not wrong. However, in this case, the blades were soaked in vinegar for a day prior to Rc test - no scale present. I have not seen a hardness tester mark yet that is so shallow that it would not fully and completely penetrate most, if not all "blade scale". You can clearly see in the photographs that the test mark has reached unscaled, sound steel.

clancy said:
correct me if I am wrong.... but I thought the forge scale was super hard and would give a false reading unless it was ground off prior to testing.

ernie
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I use parks 50 quench oil. When I first set up my shop I was having problems getting 1084 and 15N20 damascus to harden as much as I wanted. In the course of solving the problem I realized that my hardness tester always reads low. I bought new test blocks and tried every thing I can think of but it always reads 5 points low.

The bigger problem I had was the location of my quench oil. It was 3 steps from the forge and that was making a difference. Once I moved the quench next to the forge I was able to see a big difference in hardness.

ernie
 
Bush Monkey said:
Has anyone ever had a flat piece of > 1/8" barstock crack during a quench in anything? Probably not. It stands to reason that a blade that most closley mimics barstock with the largest area of "flat" would be the least likely to crack during the quench.
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For what it's worth, I've cracked 3/8" round rods quenching them in water, nearly in two, lengthwise, on medium carbon (0.4%) steel. Sometimes it just happens.
 
If you quench 1000 round rods in water and 1000 angular pieces of steel with multiple stress risers and differential thickness... in water you will always have less failures with roundstock or "balanced" stock. Anomalies happen and the exception to the rule that you experienced, although rare, happens nonetheless.

me2 said:
For what it's worth, I've cracked 3/8" round rods quenching them in water, nearly in two, lengthwise, on medium carbon (0.4%) steel. Sometimes it just happens.
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I had six more 3/16 1095 at 1500 degrees quenched in water last week - no cracks, pings or dings. I had one blade with a slight warp - ~1/8. Some square tube, C-clamps and a nickel brought it back to "true" during the temper cycle.

A water quenched 1095 blade with a warp is much more stubborn to straighten than a 1095 or 01 blade quenched in oil.

IMG_1937.JPG
 
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