Studies of the Structure and Properties of Weld Deposits of the Sv-AK5 Filler Wire in Robotized Deposit Welding

Abstract

The effect of the welding arc current (47, 57, and 67 A) on the structure and properties of the deposited samples obtained by electric arc robotic deposition has been studied. Welding wire Sv-AK5 (ER4043) of the Al-Si system was used as a filler material. The weld deposition was carried out on a substrate in the form of a plate 6 mm thick made of AMg6 alloy (Al–Mg system). In the process of surfacing, a typical two-phase structure of a hypoeutectic composition is formed in the samples, which is characteristic of alloys of the Al‒Si system with a silicon content of 5%. A trend to the enlargement of the structure in the direction from the substrate is observed along height of the deposited layers, which is associated with the accumulation of heat in the layers deposited along the height. With an increase in the welding arc current, dendrites based on α-Al and eutectic Si crystals are refined, while their density increases and microhardness decreases. The increase in density is due to a decrease in the proportion and size of gas pores and the refinement of structural components. The decrease in microhardness is associated with an increase in the proportion of the soft phase (α-Al dendrites) and a decrease in the number hard eutectic silicon crystals. The average content of silicon in the samples deposited in three modes is in the range of 5.46–5.91%, which corresponds to the chemical composition of the welding wire Sv-AK5 (ER4043). An increase in the welding arc current facilitates a growth of tensile strength and a slight decrease in the conditional yield strength and relative elongation. The patterns of the change in the mechanical properties of the deposited samples are due to the specifics of the formation of the cast structure of the deposited layers under conditions of directional solidification in the direction away from the substrate.