Welding technology questions

1. What is welding condition? What does it have? Answer: when welding the surrounding conditions, including: the base material, thickness, shape of groove, joint form, constraint condition, environment temperature and humidity, cleanliness, and in accordance with the above factors and determine the types of welding wire (or rod) and diameter, welding current, voltage, welding speed, welding sequence, deposition methods, carry a gun (or article) methods. 2. What is a welded joint? How many basic forms are there? A: joints connected by welding. The welded joint includes three parts: weld, fusion zone and heat affected zone. The basic forms of joints are: butt joint, corner joint, lap joint and t-joint. 3. What is penetration? Answer: in the welded joint cross section, the base material melting depth. 4. What is welding position? How many forms? Answer: when welding, the welding joint in the space position. There are flat welding, vertical welding, horizontal welding and overhead welding and other forms. 5. What is vertical down welding and vertical up welding? Answer: < 1 > vertical welding, the arc from the top to the bottom of the welding – called down vertical welding. Such as: cellulose welding rod down vertical welding; CO2 downward vertical welding, etc. < 2 > vertical welding, the arc from the bottom up welding – called upward vertical welding. 6. What is welded structure? Answer: the steel structure connected by welding method is called welded structure. 7. Why do butt welds have groove? Answer: groove — according to the design or process requirements, the welding parts to be processed into a certain geometric shape, after the assembly of the groove formed. In order to weld section penetration and reduce fusion ratio; Common groove forms are: I, V, Y, X, U, K, J, etc. Why are some materials preheated before welding? Answer: in order to slow down the cooling speed after welding, prevent the cold crack. 9. Why is heat treatment required for some welded components after welding? A: to eliminate residual stress and improve the microstructure and properties of welded joints. 10. Why is the welding procedure procedure formulated before welding? Answer: guarantee welding quality depend on five big control link: person, machine, material, method, ring. Person – welder’s operational skills and experience Machine – high performance and stability of welding equipment Material – high quality of welding materials Method – correct welding procedure procedure and standard operation Ring – good welding environment According to the welding test and welding procedure evaluation, the welding procedure procedure formulated before welding is the “law”, which is an important factor to guarantee the welding quality. 11. Why should the surface of the base metal be treated before welding? Answer: weld groove and surface if there is oil (paint), water, rust and other impurities, melting into the weld will produce pores, inclusions, slag, cracks and other defects, bring harm and hidden trouble to the welding joint. 12. What is the melting coefficient of wire? Answer: the melting coefficient of wire refers to the melting amount of wire per unit of time through unit of current. (g/Ah) the thinner the wire, the larger the melting coefficient, that is, the higher the efficiency. 13. What are welding process parameters? Answer: when welding, in order to ensure the quality of welding and selected physical quantities (such as: welding current, arc voltage, welding speed, line energy, etc.). 14. What is welding current? A: when welding, the current flowing through the welding circuit is generally expressed as ampere (A). 15. What is arc voltage? A: the voltage drop between the two ends of the arc (two electrodes) is generally expressed in volts (V). 16. What is welding speed? Answer: the length of welding seam completed in unit time is generally expressed as cm/min (cm/min). 17. What is dry extension? Answer: when welding, the distance between the end of the wire and the end of the conductive mouth. 18. What is welding line energy? A: during fusion welding, the energy input from the welding heat source to the welding seam of unit length is also called “heat input”. It’s usually expressed in joules per centimeter (J/cm). 19. What is the fusion ratio of weld metal? Answer: when fusion welding, the part of the base metal is melted in the proportion of weld metal. 20. What is weld shape factor? Answer: when welding, the ratio of the width of the weld and the thickness of the weld on the cross section of the single weld. What is left hand welding? A: when welding, the welding gun from the welding seam of the right end to the left end of the movement of the welding method. The effect of gas protection is good, and the welding seam is beautiful. MIG aluminum must be welded left. What is right welding? A: when welding, the welding gun from the left end of the weld to the right end of the movement of welding. 23. Why are welded joints the weak link in welded structures? Answer: because of the uneven structure and performance of the welded joint, there are often some welding defects, there is a high tensile residual stress; So the welded joint is the weak link in the welded structure. 24. Why is it said that high-quality welded joints can be obtained through the process? A: improve the quality of welding joint, can from the following ways: correct selecting welding material, adopt reasonable welding methods, control the fusion ratio, adjust the welding thermal cycle characteristics, reasonable use of the operation method and the groove design, supplemented by preheating, interlayer insulation and slow cooling, heat, or heat treatment after welding, etc., can obtain excellent welded joint.铜焊丝,Copper Welding Rods,铝焊丝,aluminium welding wire,镍焊条,Nickel electrode,药皮焊条,Flux Coated Brazing Welding Rods