Transformation of non-metallic inclusions in steel under explosive loading and heating

Abstract

Purpose. The goal of the work was to study phase and structural transformations in nonmetallic inclusions under pulsed loading and subsequent heating.Methodology. Dynamic loading of the samples of steels was carried out according to the scheme of throwing a thin plate (ihe pressure 80...90 GPa, the deformation rate was 100 sec-1, the exposure time was 1,5 · 10-6 sec). After pulsed loading, some of the samples were annealed or thermal cycling. The studies were carried out by methods: metallographic ("Neophot-21"), electron microscopic (JSM-35), petrographic, quantitative metallography ("Quantimet"). Findings. The features of the phase and structural transformations in nonmetallic inclusions under pulsed loading and subsequent heating (high-temperature annealing, thermal cycling) were investigated. It has been found that the explosive action, which creates stresses near the inclusions, influence on the nature of phase transformations during subsequent heating. Originality. The main phase and structural transformations in nonmetallic inclusions that occur at the moment of pulsed loading (polymorphic transformations, transition to an unstable state, amorphization, decomposition of solid solutions) have been determined. The effect of explosive action on transformations in inclusions during subsequent high-temperature annealing and thermal cycling (transition to a more stable state, "devitrification", diffusion crushing, separation of "satellite" particles) was shown.Practical value. The use of the results obtained will make it possible to develop modes of pulsed pressure treatment, as well as complex treatment (explosion + high-temperature annealing, thermal cycling), which allow influencing the mechanical and operational properties of steels for various purposes.