Welding process

1. What are welding conditions? What are they? Answer: The surrounding conditions during welding, including: base material material, plate thickness, groove shape, joint form, restraint state, ambient temperature and humidity, cleanliness, and the type and diameter of welding wire (or welding rod), welding current, voltage, welding speed, welding sequence, deposition method, gun (or rod) transportation method, etc. determined according to the above factors.

2. What is a welded joint? How many basic forms are there? Answer: A joint connected by welding. A welded joint consists of three parts: weld, fusion zone and heat affected zone. The basic forms of joints are: butt joint, fillet joint, lap joint and T-joint.

3. What is penetration? Answer: The depth of the base material melted on the cross section of the welded joint.

4. What is welding position? How many forms are there? Answer: The spatial position of the weld joint during fusion welding. There are flat welding, vertical welding, horizontal welding and overhead welding.

5. What are downward vertical welding and upward vertical welding? Answer: 〈1〉 During vertical welding, the arc is welded from top to bottom, which is called downward vertical welding. For example: cellulose electrode downward vertical welding; CO2 downward vertical welding, etc. 〈2〉 During vertical welding, the arc is welded from bottom to top, which is called upward vertical welding.

6. What is a welded structure? Answer: A steel structure connected by welding is called a welded structure.

7. Why do welds need to be grooved? Answer: Groove - According to the design or process requirements, the welded part of the weld is processed into a certain geometric shape, and the groove is formed after assembly. In order to melt the cross section of the weld and reduce the fusion ratio; the commonly used groove forms are: I, V, Y, X, U, K, J type, etc.

8. Why do some materials need to be preheated before welding? Answer: In order to slow down the cooling rate of the weld after welding and prevent cold cracks.

9. Why do some welded components need to be heat treated after welding? Answer: In order to eliminate welding residual stress and improve the structure and performance of the welded joint.

10. Why do we need to formulate welding procedures before welding? Answer: The quality of welding depends on five major control links: people, machines, materials, methods, and environment. People - the operating skills and experience of welders Machine - the high performance and stability of welding equipment Materials - the high quality of welding materials Methods - the correct welding procedures and standardized operations Environment - a good welding working environment The welding procedures formulated before welding based on welding tests and welding process assessments are "regulations" and are important factors in ensuring welding quality.

11. Why do we need to process the surface of the parent material before welding? Answer: If there are impurities such as oil (paint), water, and rust on the groove and surface of the weldment, they will melt into the weld and produce defects such as pores, inclusions, slag inclusions, and cracks, which will bring harm and hidden dangers to the welded joint.

12. What is welding current? Answer: During welding, the current flowing through the welding circuit is generally expressed in amperes (A).

13. What is arc voltage? Answer: The voltage drop between the two ends (two electrodes) of the arc is generally expressed in volts (V).

14. What is welding speed? Answer: The length of the weld completed per unit time, generally expressed in centimeters per minute (cm/min).

15. What is dry extension length? Answer: The distance between the end of the welding wire and the end of the conductive nozzle during welding.