rite this mite sound rather confusing

when im driving along the road the car is fine untill she warms up the i am getting a cracking banging noise from the steering you dont realy hear it as much on the out site it more on the steering wheel its self it sounds like the noise you would get going round a corner with a broking spring but that is not what the problem was,, if any one can make head nor tale of this let me know asap as the car is up for sale ha