Study On Quality Control Of Hollow Stud Welding Engineering

Because of the characteristics of stud welding and the properties of the base metal,the welding between medium carbon steel and Q235 hollow studs has many defects such as partial arc phenomenon,air hole,brittle and hard phase appear easily during welding.New methods of hollow stud welding is proposed:hollow stud spiral arc welding method and auxiliary welding agent-arc stud welding method.The welding power supply is BMH-22SV arc pull stud welder.Through process experiments,good welding joints between medium carbon steel and Q235 hollow are obtained.The rotating arc welding process of hollow stud can effectively control the track of welding arc,and make the welding arc spinning as it moves down,at the time of the welding arc downward,thereby the cross-sectional area of the arc weld can be improved effectively,eliminating welding defects,then the strength of the weld joint is improved.For the hollow studs with outer diameter of 12mm and inner diameter 6mm,the best welding parameters for the maximum strength of welded joints are:the input-voltage of the rotary arc device is 6V,the welding current is 700A,the welding time is 400ms,and the shear strength reaches 314MPa.However,there will still be some air hole in the welding line,and there is a lot of martensite in the welding line,and the impact toughness of the welding line is poor.For hollow studs,the phenomenon of "internal adsorption" and slight splash phenomenon still exist in the specimens obtained by rotary arc stud welding process,so that some inner threads of the stud are ablated by liquid metal.The welding method of auxiliary welding agent-arc stud welding is to add a certain amount of agent into the welding line.The fluidity of the welding pool is enhanced,and due to the thermal reaction can increase the sum of the heat input of the welding,we can get a complete appearance of a protruding platform,without airhole and not fusion welding defects.For the hollow studs with diameter of 12mm,the best welding parameters for the maximum strength of welded joints are:auxiliary welding agent amount is 0.25g,welding power current access value and welding time are 700A and 400ms,respectively.The strength of welded joint under this parameter reaches 335MPa.And because of the addition of the auxiliary welding agent,the composition of the brittle hard phase in the weld joint is less,and the plastic toughness of the weld joint is greatly improved.