How do I properly harden steel?

[xBMW M3 GTR]

I have some pick blanks (sections of engine dip sticks from the junk yard) and I have made several picks from this material. Each dipstick varies in strength and flexibility. I have some thin hook picks that like to bend back when using to lift and spring right back up, and others dont bend as easily, but still have springiness to them. alot of these came from the same dip stick but some as said, are harder than others probably from the heat due to grinding, but how can I make all of my picks harder and stronger without making them too brittle?

[Oaklandishh]

I have never tried this, but it seems legit.
http://www.ehow.com/how_4531756_harden-steel.html

[maintenanceguy]

Every type of steel requires needs to be heat treated differently. The hardness and "springyness" of the steel is more reliant on what's in the steel than how it's heat treated. But...

Heat treating steel is a 2 step process (most of the time). First you would first heat the steel to a specific temperature and quench the steel to cool it quickly. Oil is usually used to do the quenching because water will cool the steel too quickly. This makes the steel very hard. But, hard steel is also brittle. Without knowing the type of steel, I'd try heating to a dark purple or very dull red but not yet glowing and quench in motor oil. To see the steel color, use emery paper to make a small patch clean and shiny before you heat it and look at this area to see the color.

The second step is called tempering. You heat the steel to a specific (but lower) temperature and hold it at that temperature for a specific amount of time and let it slowly cool. This "tempers" the steel or removes some of the brittleness (at the expense of hardness). Without knowing the steel again, I'd use a straw yellow as the indicator color before quenching.

Heat treating will only work if you're using a steel that can be hardened this way.

[Poff]

I have never tried this, but it seems legit.
http://www.ehow.com/how_4531756_harden-steel.html

I used this method to harden a press tool. It worked pretty well. I also did as maintenanceguy said and put it in the oven and heated it up to 500* and let it cool on it's own in the air. I do not know how well I did on a scientific level but the steel was harder that when I started. I don't think I got it hot enough during the first step though. It could have been a little harder. I am going to try it again.

[Buggs41]

As an electrician, and using a fish tape quite a bit, I find the steel snaps the H*ll out of your fingers if it snaps while bending it into a hook tip.

What is the best way to prep the end for easy bending? Air cool, or quench.

Our 'helpers' seem to have a habit of snapping off the ends while wire pulling, or creating such a spaghetti mess of fish tape on the floor, the only option is to cut the tip off.

[maintenanceguy]

I use fish tapes a lot too.

I usually heat the tip with a propane torch and bend it hot. If you heat it and let it cool slowly, that also leaves the steel much more ductile and you can bend it cool without it snapping.

If you were to re-heat the steel and quench it, it would definitely harden. Fish tape is a very hard steel, probably a spring steel and hardens easily.

[Buggs41]

Maintenanceguy,

Thanks for the reply, I will definately try the heat, 'air cool' approach.