Model of interaction between laser radiation and metal powder composition during direct laser growth

Abstract

This paper presents a model for analyzing the interaction of laser radiation and a metal-powder composition in the process of direct laser growing of large-sized combustion chambers of gas turbine engines. The metal-powder composition is fed into the melting zone coaxially with laser radiation; the task is to completely melt the powder with laser radiation before it enters the melt bath on the construction platform. The laser radiation is absorbed as it passes through the gas-powder jet, and its energy is also used to melt the construction platform or the previous layer. Thus, in order to determine the parameters of the operating conditions that provide the possibility of melting powder particles, it is necessary to determine the boundaries of the parameters at which each particle of the metal-powder composition completely melts in a gas-powder jet. To simulate heat transfer inside a particle, the Beer – Lambert laser radiation absorption law was used using the lumped parameter approach. The required energy for melting the powder material was determined through enthalpy. The resulting one-dimensional differential equation of enthalpy increment is solved numerically by the Euler method. Using this model, the distance from the point of origin of the interaction of the laser beam with a metal-powder composition to the zone of its complete melting was determined and the effect of the velocity of the gas-powder jet, the power of laser radiation, the bulk density of the metal-powder composition and the average radius of the powder particles on the distance to the zone of complete melting was studied.

Keywords

• additive manufacturing
• direct laser growth
• heat-resistant chromium-nickel alloy
• beer – lambert law
• enthalpy of fusion
• heat transfer within powder