Part 3: Improvised heat treating techniques for knives & tools.

Lets talk steel. in reality there are very few steels that cannot be heat treated using old fashioned methods some will simply take a little more creativity than others. However there are steels that lend themselves nicely to these techniques such as

 5160 spring steel and 0-1 tool steel which we will cover here. The best part is that both of these excellent steels are readily available to anyone.


We will start with 5160 high carbon spring steel


5160 spring steel is a very common carbon steel used in old American vehicle leaf springs these are easily found at most salvage yards and have a typical thickness of about 1/4 inch. However the down side to this steel is that it must be annealed before use which is a process we will cover here.


Step one: Annealing. This is actually very easy to do with this grade steel. Simply start by preparing the fire pit and fuel as described in part 2 and allow the wood to burn down until a nice red hot bed of coal is all that's left. Then carefully place the steel on top of the coals and rake a thin layer over it. Once the coal cools (turns black) allow the steel to stay put and warm up for a few minutes then move it to a new location in the pit and rake a new layer of coals over it. When the steel turns the same color as the red hot coal let it soak for 5-10 minutes then remove and allow it to air cool; this should bring it down to a more workable hardness level.


Tip: Place the steel in the coals just before the fire burns out to get the most out of the bed of coal.


Tip: when the steel is removed for air cooling; and still red hot it can be pressed flat (straightened).






Step two: Grind the steel to the desired shape/design. If making a knife grind/file the edge bevels and drill all handle pin holes before proceeding.




Step three: Prepare the fire pit and fuel as described in part 2 and allow the wood to burn down until a nice red hot bed of coal is all that's left.


Note: Ideally the bed of hot coal should be at least 4-6 inches deep (the deeper the better)

Step four: Carefully place the steel on top of the coals and rake a layer over it. This will cool the coals down a little as mentioned above. Allow the steel to stay put for a while and warm up then move it to a new location in the pit and rake a new layer of coal over it. Once the steel becomes the same reddish color as the coals it should be in the 1500 degree range and ready to quench.

Note: the cooler coals in the center where the steel is located

Tip: Place the steel in the coals just before the fire burns out to get the most out of the bed of coal

Tip: If the coals and the steel look a little too cool fan the top of the coals to bring the temperature and color into the desired range (see temp color chart).

Step five: Remove the steel from the coal and quench immediately by submerging completely in oil. Once the steel enters the oil it will begin to boil (and in most cases burst into flames and smoke profusely). Submerge the steel in the oil until the oil stops boiling then lift the steel out of the oil and submerge again repeating 3 to 4 times (submerging for 20-30 seconds each time) then place the steel on the metal rack described in part 2 for cooling. Once at room temperature it should be in the 60-62 Rockwell hardness range.

Quenching oil

Note: see part 2 for recommended oil to steel ratio.

Additional tempering of 5160 steel is optional

If applying additional tempering quench the steel down to approx 125F then begin the tempering cycle immediately by heating the steel to 300F and soaking for 1 or 2 hours.






Keep in mind that these techniques
are for applying an improvised heat treat.
Rockwell hardness is approximate