Self-shielded flux-cored welding wire with special protective slag coating formed in situ and manufacture method thereof

#This application claims priority to Chinese Patent Application Ser. No. CN201911272500.X filed on 11 Dec. 2019.

#The present invention belongs to the field of welding in material processing engineering, and more particularly, relates to a self-shielded flux-cored welding wire with special protective slag coating formed in situ and manufacture method thereof.

#Since the birth of welding technology, welding slag plays an important role in welding metallurgy, but the welding slag has always been treated as an inevitable by-product, and deslagging is required after welding, so that a lot of labor hours are consumed, and waste slag discharge also causes serious pollution to the environment. A deslagging property is one of the key process property indexes in development of a self-shielded flux-cored welding wire, and difficult deslagging of bonded slag restricts a welding process property.

#The present invention can be better understood according to the following embodiments. However, a specific ratio of ingredients of a flux core, process conditions and results thereof described in the embodiments are only used for illustrating the present invention, and should not and will not limit the present invention described in detail in the claims. A glass powder used in the following embodiments includes 57.2% SiO2, 22.8% B2O3, 5.7% Na2O, 9.2% CaO, 3.2% ZrO2 and 1.9% Al2O3, a rutile powder includes no less than 98% TiO2 and the balance of impurity elements Fe, Nb, Ta, Cr and Sn, and a corundum powder includes no less than 99% Al2O3 and the balance of impurity elements Cr, Ti, Fe and V.

#A special protective slag coating formed in situ was prepared by evenly spreading a flux core powder on a Q235 steel plate through an arc fusion welding method in which a tungsten electrode was used as a non-consumable electrode. The Q235 steel included chemical ingredients of no more than 0.22% C, no more than 1.4% Mn, no more than 0.35% Si, no more than 0.050 S and no more than 0.045 P. The flux core powder was prepared according to the following masses: 80 g of glass powder, 2 g of zirconium oxide powder, 0.5 g of graphene powder, 2 g of sodium potassium carbonate powder, 2 g of potassium titanate powder, 3 g of rutile powder, 1 g of corundum powder, 1 g of sodium fluorosilicate powder, and 8.5 g of iron powder. When the coating was prepared by the arc fusion welding method, a height of the spread flux core powder was 2 mm, a welding current was 150 A to 250 A, a welding voltage was 18 V to 25 V, and a welding speed was 0.1 m/min. Please refer to Table 1 for results of seawater corrosion resistance test of surface-vitrified slag coating after fusion welding and results of combination test between slag coating and welded joint.

#A special protective slag coating formed in situ was prepared by evenly spreading a flux core powder on a Q235 steel plate through an arc fusion welding method in which a tungsten electrode was used as a non-consumable electrode. The Q235 steel included chemical ingredients of no more than 0.22% C, no more than 1.4% Mn, no more than 0.35% Si, no more than 0.050 S and no more than 0.045 P. The flux core powder was prepared according to the following masses: 60 g of glass powder, 4 g of zirconium oxide powder, 0.05 g of graphene powder, 8 g of sodium potassium carbonate powder, 3 g of potassium titanate powder, 2 g of rutile powder, 3 g of corundum powder, 3 g of sodium fluorosilicate powder, and 16.95 g of iron powder. When the coating was prepared by the arc fusion welding method, a height of the spread flux core powder was 2 mm, a welding current was 150 A to 250 A, a welding voltage was 18 V to 25 V, and a welding speed was 0.1 m/min. Please refer to Table 1 for results of seawater corrosion resistance test of surface-vitrified slag coating after fusion welding and results of combination test between slag coating and welded joint.