Preparation And Properties Of Hot-Dip Aluminizing Wire

MAG welding wire on the market is still the main copper-plated wire,in order to obtain good resistance to rust,conductivity and good wire performance.However,the impact of waste water on the environment caused by the waste water in the production process of copper-coated wire and the impact of the welding process on the health of the welders is becoming more and more important.Therefore,the principle and production process of the non-copper-coated wire have become the research in recent years Hot spots.This topic has tried to hot-dip aluminum to the wire in order to protect the wire substrate thus instead of the traditional copper wire.Hot-dip aluminum wire is the surface coating process which put the pre-treated wire immersed in molten aluminum liquid,after a certain period of time to a certain pulling speed vertical wire from the aluminum liquid pulled out,making the wire surface coated with aluminum coating.In this paper,the hot dip aluminized wire was studied in all directions.The morphology of the coatings,binding of the wire,coating corrosion resistance,rust resistance and wire welding quality,mechanical properties all of them have been researched.The research shows that the coating is divided into two layers,outer layer is the aluminum-rich layer,another layer is Fe-Al alloy layer.Because of the existence of the alloy layer,it is proved that the welding wire and the aluminum rich layer have a strong metallurgical bonding.The morphology of the coating was analyzed by metallographic microscope,SEM and EDS.The alloy layer was zigzag-shaped perpendicular to the axis of the wire,and consisting of FeAl₃,Fe₂Al₅,and Fe₂Al₅ phase occupy most of the alloy layer.The results show that the thickness of the aluminum-rich layer is mainly affected by the viscosity and fluidity of the bath under the condition of certain pulling speed.The thickness of the alloy transition layer increases with the time of dip plating at the same temperature,and with the temperature increasing the thickness of the alloy layer first rise and then decline.Hardness test results show that the outer layer of aluminum’s hardness is about50¹00HV,intermediate alloy layer’s hardness is 500⁶00HV.It shows the intermediate alloy layer is brittleness.The addition of alloying elements Si in molten aluminum can change the thickness and morphology of the coating which intermediate alloy layer thickness by pure aluminum is 170μm reduced to 5μm,the patterns of it from serrated growth to smooth shape and mechanical performance were greatly improved.Combined with the aluminum welding wire,corrosion resistance,rust resistance showed better characteristics too.The aluminum alloy wire was welded under the protection of active gas（mixed gas of20%CO2+80%Ar）and the inert gas（pure argon and 0.5%N2+99.5%Ar mixed gas）.The appearance of the weld was observed,the results show that with the increase of the amount of aluminum,the forming of the weld becomes worse.This is because a large amount of Al passes through the welding wire into the weld,which increases the viscosity of the metal in the bath and decreases the fluidity.Eventually,the weld seam is not fused and the weld is not penetrated.The mechanical properties of welded joints show that the impact toughness and tensile strength of welded joints will be reduced with the increase of Al content in welding wires.No matter which protective gas is adopted,the strength and impact energy of the weld metal prepared by hot-dip aluminizing welding wire are lower than those of the copper welding wire prepared by 20%CO₂+80%Ar mixed gas protection.