I remember doing an experiment in college, but I don't remember the kind of heat treated steel that was used (high carbon [1095] or low carbon), but it was 1/4 inch solid square rod. We heated treated the steel with a torch in three places in three different ways.
1. The first spot we heated to some color (I want to say red) and let air cool.
2. The second spot we heated to the same color and immediately quenched in water.
3. The third spot we heated to the same color, immediately quenched in water, then re-heated to blue and let it air cool.
We then tried to determine the characteristics of the three spots. Spot 1 was soft, and bent easily, but was very tough. Spot two was HARD, and brittle, snapping quite easily. The third spot that was "double tempered" was still quite hard, and was very tough, and was MUCH stiffer than the surrounding metal (we bent the rod on both sides of the "double tempering").
I told you all of this so I could say that the quarter inch stock we used was heat treated to the center, which should mean that the quarter inch stock you are using should be heat treated to the center. Just make sure when quenching, you allow enough time to drop the internal temperature of the steel to where it needs to be. Naturally, this assumes the same type of steel...
1. The first spot we heated to some color (I want to say red) and let air cool.
2. The second spot we heated to the same color and immediately quenched in water.
3. The third spot we heated to the same color, immediately quenched in water, then re-heated to blue and let it air cool.
We then tried to determine the characteristics of the three spots. Spot 1 was soft, and bent easily, but was very tough. Spot two was HARD, and brittle, snapping quite easily. The third spot that was "double tempered" was still quite hard, and was very tough, and was MUCH stiffer than the surrounding metal (we bent the rod on both sides of the "double tempering").
I told you all of this so I could say that the quarter inch stock we used was heat treated to the center, which should mean that the quarter inch stock you are using should be heat treated to the center. Just make sure when quenching, you allow enough time to drop the internal temperature of the steel to where it needs to be. Naturally, this assumes the same type of steel...