Dragomeretska O. Impact of Crystals and Residual Stresses' Orientation on the Coercive Force of Some Ferroalloys

The object is the crystallographic texture, microstructure, anisotropy of coercive force, mechanical characteristics under uniaxial tension in iron-based alloys after rolling and annealing. The goal is to develop a physical model of the coercive force coupling with a crystallographic texture, strength and plasticity characteristics, residual lattice stresses and microstructure in some iron alloys and structural steels. Methods of investigation - X-ray analysis of the texture and substructure of crystalline bodies, metallographic analysis, methods of mechanical testing of polycrystals, non-destructive method of measuring coercive force using a coercimeter, computer simulation. Scientific novelty of the results obtained: 1. A physical model is proposed for the appearance of an anisotropy of the coercive force when an external magnetic field is applied in different crystallographic directions due to the different work of magnetization of crystals in polycrystals. 2. It has been established that during cold rolling of a polycrystalline Fe-3% Si alloy, the coercive force is increased by a factor of 2, with the anisotropy invariable. 3. It is shown that, after annealing the rolled samples of polycrystals of the Fe-3% Si alloy, the anisotropy of the coercive force is due to the shape and size of the grains due to the peculiarities of the dynamics of the domain structure. 4. It has been established that in steel 15X5M an anisotropy of the coercive force takes place, which is due to the amount of work on the reorientation of the magnetization vector from the direction of easy magnetization <100> to the superposition of the field, in the direction of heavy magnetization <110> when a magnetic field is applied due to magnetic crystallographic anisotropy. 5. It is shown that the method of measuring the coercive force was more sensitive to a change in the phase composition of stainless steel than the X-ray phase analysis, since the presence of a magnetic phase and the anisotropy of the coercive force in samples of 08Х18Н10Т steel, in contrast to the X-ray phase analysis. 6. The magnitude of the coercive force and its anisotropy in austenitic-unstable steels is determined by the amount of the martensitic phase and the nature of its texture. 7. It is shown that the cause of the anisotropy of the coercive force of steel 09G2C is the magnetic crystallographic anisotropy due to the nature of the texture. The practical significance lies in the fact that the obtained results of the investigation can be used to develop the theory of magnetization taking into account the crystallographic texture; When developing a non-destructive method for controlling the structural state of steel by a coercive force; To control the stress-strain state of steel during operation; For the development of new PNP steels with specified properties.