About Wave Nature of the Formation of Gradient and Microcomposite Zones Near Non-Metallic Inclusions During Laser Processing of the Steels

Abstract

Abstract: The goal of this investigation was to research the wave nature of the formation of gradient and composite zones near non-metallic inclusions during laser treatment of the steels. The materials for investigation were commercial steels containing different non-metallic inclusions. The specimens of different steels were exposed to laser beaming on the installations GOS-30M. The research methods were applied: petrography, X-ray microscopy (MS-46 Cameca, "Nanolab - 7") and optical microscopy (Neophot-31) to study steel matrix near non-metallic inclusions and to identify of the inclusions. Nanohardness of the steel matrix near inclusions ("Nano Indenter II") was analyzed. Peculiarities of wave saturation of the steel matrix by chemical elements of non-metallic inclusions during laser action were investigated. It was shown the role of wave relaxation of stresses in the formation of cascade type structure of steel matrix near non-metallic inclusions. The features of the formation of gradient and micro composite saturation zones of cascade type in a steel matrix under conditions of abnormal mass transfer from nonmetallic inclusions during laser processing are discussed. It has been established that the formation of gradient saturation zones with a cascade and “spot” distribution of elements and nanohardness is due to the wave nature of the relaxation of thermal and deformation stresses near non-metallic inclusions at the time of laser exposure. The difference in the rates of abnormal mass transfer of chemical elements of non-metallic inclusions into a steel matrix at the moment of laser melting is shown, which is associated with different solubility and mobility of the atoms of alloying elements in liquid iron.