I assume you are talking about warping. Right? If you are heating it unevenly, letting it start it's cooling unevenly, or if the grind is uneven from side to side, you can get warping.
Grind even and thermocycle
Heat in oven or forge or control your torch better. This should be done in a calm area with no air movement. Turn all fans off, close doors and windows if it's windy.
Immediatly put the blade in lime or some insulating medium. Be careful not to get rough with it while placing in the lime.
Wait a few hours. This should work. Lin