EUR 5.-How Can one calculate the magnetic field required to induce feromagnetic materials?

I need to calculate the strength of a magnetic field required to magnetize a metallic mesh framework made out of permendur (Fe and Co combination) to about 4 KOe (kilo Oersted).

I am looking for formulas and explanations of how a magnetic field induces metals to be magnetic as well. For example if an iron nail is held stationary (not in contact) near a magnet the nail becomes magnetic and another nail if near to the original nail will be magnetically attracted to the first nail. How, and why does this work?

I am interested in all sorts of answers so please feel free to comment, however I will only accept solutions giving formulas and explanations completely answering this question.