Porosity Formation in Thin Welded Joints of Al–MG–LI Alloys

Abstract

This work is about the study of the correlation of pore formation in welded joints of Al–MG–LI alloy with zirconium additives with the state of the base metal, thermal vacuum treatment, and welding technologies MIG and EBW. Metallographic analysis has been carried out, the phase composition of the alloy and weld metal has been investigated, and thermal cycles of welding have been calculated, allowing to estimate the residence time of metal in the alloying zone and weld metal in the liquid state. The nature of the allocation of strengthening fine-dispersed phases in the welded joints of the alloy has been determined. The regularity and character of pore formation in welded joints depending on the applicable thermal vacuum treatment (TVT) and welding technology have been revealed. It was established that TVT with subsequent hardening and aging has no effect on the phase composition of the alloy. However, this type of treatment contributes to the formation of a more homogeneous and uniform nature of the separation of fine-dispersed strengthening phases. It was revealed that the MIG technology (metal with and without TVT) is characterized by a large length of the fusion zone, the high residence time of metal in the fusion zone and weld metal in the liquid state, and the formation of pores. Phase formation in the temperature range of the beginning and end of the alloy crystallization occurs not only in the weld at the final stage of crystallization but also in the fusion zone, which may induce pore formation, whereas EBW welding shows the opposite trend and no pores. It was found that EBW technology prevents pore formation and makes it possible to obtain welded joints of 1420 Al alloys of the required quality.

Numerical Simulation of Thermal Field and Performance Study on H13 Die Steel-Based Wire Arc Additive Manufacturing

“…However, it was hard to measure thermal physical performance parameters of metals at a high temperature, especially at the solid-liquid interface temperature. Thus, in the present study, the thermal physical performance parameters of H13 steel at different temperatures were calculated using Jmatpro simulation software [25,26]. Furthermore, the accuracy of the simulation was verified and the parameters were corrected according to the previous study [27].…”