Doghouse Update for mid October.
This one will be fun. Theres a cool Chef cleaver with a new handling process as well as the exciting news that the rasp steel mystery is finally solved.
There is also a rather complex but satisfying attempt at forging a Calla Lilly Plant. Ha! yes, I said plant.
Before the fun projects I would like to update the metalurgy information just in case someone is actually using my trials to build their own blades.
Here is the most current and the most accurate process and tolerances that Doghouse Forge has learned and applied to date:
The steel mystery finally came to an end and Im happy to report that the rasp steel couldnt be more user friendly for knife making. (aside from being one of the hardest possible alloys)
Its W-2 blend steel. Its similar to W-1 except thie alloy blend uses vanadium and tungsten. Im not positive as to the exact amount since he wouldnt tell me, but it has to be somewhere between .1 and .25% in order to qualify as W-2. Its a very common steel used in file making and is rather difficult to purchase as straight bar w-2 so my seemingly endless rasp pile is a great resource. The properties are very similar to 1095 carbon steel, which is the most common knife making steel.
So real quick, some steel label education. Its sad that Im just now understanding this stuff but I guess mild steel isnt really something you worry about the content for if its simply for creating horseshoes.
What do the letters and numbers stand for???
I have only started to learn this stuff so this is the basic into that i have been given. As I educate myself and learn more I will hopefully be able to use different steels with a proper understanding of their properties.
The
W stands for water hardening steels, the
O stand for oil hardening, and the
A steels are air hardening. the A steels are the deepest hardening becuase they never really stop harding.
The numbers stand for a lot of different things but for this reference Im just going to break down the basics.
1 indicates carbon steel 1XXXX
4 indicates molybdenum steel 4XXXX
5 indicates chromium steel 5XXXX
6 indicates chrome vanadium steel 6XXXX
8 indicates nickel chromium molybdenum, steel 8XXXX
9 indicates silicon manganese steel 6XXXX
The second number indicates any additional elements that affect the steels properties.
the third and fouth give the carbon content of the steel
So as an example: a very common tool steel is 1095 -
this steel is a carbon steel with no additional elements and 95% carbon content.
If by chance the steels number was 1195 it tell you that it has an additive.
This number would mean that its a carbon steel, with sulfur added, and 95% carbon. I unfortunatly dont know what every number for aditional elemenst is but at least when Im ordering or finding steel the what and how will be a little clearer to understand. Several cahrts are available online that discuss this method for lableing steel in great depth.
As for the tempering, anneling, and hardening the process is the simplest and easiest with water hardend steels.
here is a list with the particular properties and tolerances for W-2 carbon steel:
Treatment Temperature Range Cooling/Quenching:
Forging
1700-1900° F
Heat slowly to maximum temperature.
Forging should begin as soon as the section is uniformly heated through.
Annealing
1400-1450° F
Cool slowly in the furnace at a maximum rate of 50° F per hour/s..
Protect against surface decarburization by pack-annealing. Hold at temperature for 1 hour.
Stress Relieving
1200-1250° F
Cool slowly in air.
Stress relieve after rough machining
Preheating
1200-1250° F
Preheat time in furnace is ¾ Hr. per inch of thickness
Hardening
1375-1450° F
Quench In water or in a brine solution immediatly upon removal from critical temp.
Tempering
Recommended temperature is 350-550° F
Temper immediately after hardening and quenching..
recommended soak time is 2 hours per inch of thickness.
The tempering scale to determine the rockwell hardness upon completion of the low heat soak looks like this:
Rockwell hardness by definaition is defined by wikipedia - The Rockwell scale is a hardness scale based on indentation hardness of a material. The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload
tempering in rockwell hardness by temp/saturation is as follows:
Quenched at 1450deg - as quenched 67HRC
Quenched at 1450deg - at 300deg - 64HRC
Quenched at 1450deg - at 400deg - 61HRC
Quenched at 1450deg - at 500deg - 59HRC
Quenched at 1450deg - at 600deg - 55HRC
Now understanding whats listed above and actually being able to calibrate it takes more than the forge, water bucket, and oven. Thats why the knife makers have furnaces/kilns to do the treating process. My mentor has a time controlled programable kiln for his blades and i see now why its such an important part of his process.
Here's a chart with the temperature to color relationship. Its not as accurate as a thermometer but at least it will get you in the ball park.
So the process for the cleaver that will be posted next used this information and was adhered to as closely as I was able to achieve. Since I do a "mixed forge/stock removal" blade build, instead of a "stock removal" blade I take a temper after the initial forging and hardening before i cut out the finished shape on the band saw. This extra tempering really made the metal easier for the band saw to handle and the cut time was noticably shortend. It also made the initial grinding and shaping much faster. Once the blade has reached the thickness and shape I looking for the blank is tempered again before the final edge is ground.
So thats where the science is at in the Doghouse as of October 2013. Hopefully ill read this post in 6 months and say "man you left out a ton of steps to make it easier and better" but at least for now Im producing a quality blade that has it roots in a solid build system.
The next thing to learn is how to establish a good differential tempering so I can harden the cutting edge and soften the spine at the same time. This is gonna prove needed when i make the longer, super thin fillet knives I have in mind. Flexible and rock hard will prove to be a tricky combo in sure.
Ok, no more boring technical stuff and on to the fun photo filled build post.
Thanks
JP