The effect of the molten weld pool on the non-uniform penetration of the parent metal at of surfacing

Abstract

The data of the molten weld pool influence on the increasing non-uniformity of the parent metal penetration during submerged arc surfacing using one or two strip electrodes have been presented. The experimental results of the investigation show that non-uniform penetration of the parent metal is influenced by the mass and heat flow in the weld pool. The axial bottom flow of the liquid metal during surfacing with one and two strip electrodes results in non-uniform penetration of the parent metal. In the process of submerged arc surfacing using two strip electrodes, the liquid weld metal flow and the penetration of the parent metal depend on the ratio of the current in the first and second strip electrodes. When the current in the first and second strip electrodes is the same the distribution of the temperature and flow rate across the width of the weld pool is not uniform. It leads to mass and heat flow just in the middle of the weld pool and non-uniform penetration of the parent metal with the bottom flow. The non-uniform penetration of the parent metal is influenced by the axial bottom flow. It is shown that raising the fraction of the current in the second strip electrode up to 0,6 from the total current increases the intensity of the circulation of the molten slag; its temperature becomes more equal which changes the flow rate across the width of the weld pool. The difference of the value of the maximum and average temperature, enthalpy and viscosity of the molten weld pool decreases, what influences on flow rate of the liquid metal. The experiments show that the non-uniformity of the parent metal penetration decreases