Quote:olive oil
Don't you mean any kind of oil. In my metalegy class you can use water, air, salt water (brine), and oil (I use non detergent motor oil).
Quote:i've got some nepalese (Gurka) kukri they make out of truck spring steel stock
Unless it is very cheap knife then it is proably ment to bend some. It will not break in half this way.
Quote:Is it possible? What should i do to harden it?
Reheat it until is hot, you will know if it is at the right temp if you stick a magnet to it and it does not stick to it. That tells you that it is at the right tempature. Then rapidly cool it (in oil, water, air, or salt water). The faster you cool it the harder (generally, if it has enough carbon in it to begin with) it will be. Having a rockwell scale would be good to see how hard it is. Then just temper it about once to stress releave it and you arre done. All of this depends on the amount of carbon you have in the steel to begin with. If you have very little you may need to add carbon with a carboninzing poweder. If you have a lot of carbon the more you will proably have to temp the blade.
Quote:would it be a reliable blade after the hardening?
Yes it is at the right hadness at the end. Remember you don't want something like what you have to be over a 60- 55 rockwell. It will proably be to hard for such a long knife. I would think anything under a 40 rockwell wouldn't be good either, to soft. I hope this helps.