In the current chapter, the deformation of non-metallic inclusions in a tire cord steel and a non-oriented silicon steel during rolling and processing was investigated. The evolution of oxide inclusions in the industrial rolling process of tire cord steel billets with different types of inclusions was analyzed. The evolution in the composition, number, and size of oxide inclusions during steel hot rolling were analyzed. The deformation of oxide inclusions during hot rolling and the evolution of oxide inclusions deformation were revealed. The evaluation of inclusion deformability during steel cold drawing and the Young’s modulus of Al2O3-SiO2-CaO and Al2O3-SiO2-MnO inclusions was predicted. For the non-oriented silicon steel, the influence of oxide inclusions on the magnetic properties of the steel was investigated. The deformation of different types of oxide inclusions and their effect on the grain size and magnetic properties of non-oriented electrical steels were investigated.