strange damascus pattern in my blade

[rotor]

I have a dagger that I have made i used a piece of steel that I had found in a construction dumpster i havent a clue what type of steel this was but I cut it out to to the shape I wanted and ground down I fired and quenched it about 15 times every time I quenched the blade it seemd to get a little harder heres the weird thing i noticed a damascus like pattern I thought it was only on the surfacebut no matter how much i buff and polish it wont go away and it gets more pronounced as the blade ages and looses its luster could any one enlighten me to what is going on.