Melting refractory particles inoculators carbide and titanium nitride in the metal melt

Abstract

Purpose. In the past few years to improve the quality and reliability of welded structures for special purposes of great interest is the use of specially prepared nanopowder inoculators (NPI) as effective modifiers structure of weld metal. However, there are some reasonable fears that the particles themselves are not directly inoculatorinfluence on the structure of the weld due to their possible dissolution in the molten metal weld puddle. In this regard, the goal of the work was the modeling of the phase transition process solid / liquid phase by dissolving refractory nanopowder inoculators TiC and TiN in the metal of the weld pool and to optimize parameters of the particles providing high mechanical properties of the weld metal. Methodology. Introduction inoculators TiC particles and TiN in molten weld puddle welding was performed by utilizing the flux-cored wires in which the core is injected dispersion (10 ... 100 nm) of compound carbides TiC and titanium nitride TiN, obtained by CBC synthesis. To carry out computer simulation used the calculated physical modeling package COMSOL Multiphysics. Dissolution kinetics modeling was conducted for the particles of different particle sizes (100nm, 1 mkm and 10 mkm) and shapes (spherical, square), which were placed in a molten metal iron at temperatures of 2000°C and 2200oC.Findings. On the basis of the joint solution of the problem of heat conduction, diffusion and hydrodynamic fluid motion of the molten metal with the movement of the interface metal-melt developed a computer program for modeling the kinetics of dissolution of the particles in the metal of the weld pool. The influence of particle size and initial velocity of the melt on the kinetics of dissolution. It has been shown that the lifetime of the particles in the liquid bath is from 4 to 20, whereby some fraction of particles inoculators can be completely dissolved in the metal of the weld pool. Determine the magnitude and kinetics of changes in temperature, concentration, power and velocity fields both in the particles and melt. Originality. On the basis of mathematical modeling methods scientifically proved the possibility of controlling the parameters of the particles inoculators in the weld pool and as a consequence, the ability to influence the processes of crystallization and the
formation of the structure of the weld metal. Practical value. The use of nanoparticles inoculators in metallurgy of the weld pool will enhance management practices crystallization of the weld pool and provide due to changes in the structure of the high level of mechanical and viscous characteristics of the weld metal.