20 16 welder examination questions and answers

I. Fill in the blanks (3 points for each question, 30 points for * * *)

1. In manual arc welding, alloying welding is mainly through the transition between (core) and (coating).

2, welding is through (heating) or (pressure), or both, and with or without filler, so that the weldment can achieve (atomic bonding).

3. (Welding process parameters) refers to all physical quantities selected to ensure welding quality in the welding process.

4. The safe voltage during welding is (36V).

5. Black metal refers to the alloy of (iron) and (carbon).

6. Stainless steel is based on (ordinary carbon steel), and a group of alloying elements with chromium content greater than 12% are added, so it has the characteristic of (no rust) under the action of air.

7. The most dangerous failure form of stainless steel is intergranular corrosion.

8. When welding low alloy structural steel, there are (cold cracks), (hot cracks) and reheat cracks in the welded joint, especially (cold cracks).

9. According to the different intermittent conditions, welds can be divided into (positioning welds), (continuous welds) and (intermittent welds).

10. Generally, the length of each tack weld is (10~20 mm), and the residual height of the weld is not more than (2 mm).

Second, multiple-choice questions (2 points for each question ***20 points)

1, welding dust contains 7~ 16% SiO2, which will cause (b) if inhaled for a long time.

A, anemia B, silicosis C, nasal ulcer

2, welder work, should wear (a) canvas overalls, in case of electric arc burns the skin.

A, white b, blue c, gray

3. When welding metal containers or pipes and wet places, the lighting safe voltage is (C) volts.

a、36 B、24 C、 12

4, electro-optic ophthalmia is caused by strong (b) arc.

A, infrared ray b, ultraviolet ray c, visible light

5, manual arc welding, the type of welding power supply should be selected according to (c).

A, covered electrode diameter b, weldment thickness c, covered electrode coating performance.

6. The groove angle of the V-shaped groove (refers to the composite angle on both sides of the groove surface) is generally (B) degrees.

a、45 B、60～70 C、90

7, back welding head and tail method is suitable for (b) arc.

A, acidic covered electrode b, alkaline covered electrode c, acidic and alkaline covered electrode.

8, vertical welding, the middle bead filling should be appropriate to do lateral swing, so that the two sides of the groove fusion is good, on both sides of the groove should be (a).

A, stop for a minute. B, turn around slowly. C, turn around quickly

9, flat butt welding, covered electrode slope along the welding direction is generally (b) degrees.

a、40 ~ 50 B、60 ~ 75°C、80 ~ 90°

10, the five common elements in steel are (a).

A, carbon, manganese, silicon, sulfur, phosphorus B, iron, carbon, manganese, silicon and vanadium

Carbon, iron, manganese, carbon, sulfur and phosphorus

Three true or false questions (2 points for each question ***20 points)

1, China's safety production policy is "safety first, prevention first, comprehensive management". ( √ )

2. According to the safety regulations of special operators, operations that have great harm to the operators themselves, especially to the safety of others and surrounding facilities, are called special operations. ( √ )

3. The explosion caused by direct heating of oxygen cylinder belongs to chemical explosion. ( × )

4. The explosion occurred when the gasoline tank was welded is a physical explosion. ( × )

5, level 1 hot work should be approved by the security department or fire department. ( √ )

6. Hot work in no-fire areas, flammable workshops, pipelines and their surroundings is called first-class hot work. ( √ )

7, general maintenance when hot, a hot time shall not exceed three days. ( × )

8. Welding direction refers to the moving direction (√) of welding heat source in the welding length direction during welding operation.

9. The distance between two welding toes on the welding surface is called weld width. (√)

10, alkaline covered electrode welding In order to prevent blowholes, the method of repeatedly breaking arc and closing should be adopted for closing (x).

Fourth, short answer questions:

1. What is the purpose of annealing?

Answer: reduce the hardness of steel and improve the plasticity to facilitate cutting and cold deformation; Refine grains, homogenize the structure and composition of steel, improve the properties of steel or prepare for future heat treatment; Eliminate residual internal stress in steel and prevent deformation and cracking.

2. What are the main functions of core and coating?

Main function of the cored wire (1) The cored wire is used as an electrode; (2) After the welding wire is melted, it becomes a filler metal and forms a weld with the melted base metal;

The main function of the coating is (1) mechanical protection; (2) metallurgical treatment; (3) Improve the welding process performance of covered electrode.

3. What are the adverse effects of excessive welding current?

Answer: When the current is too large, covered electrode is prone to reddening, which makes the coating deteriorate and easily causes defects such as undercut and arc pit. At the same time, it will overheat the weld and make the grain coarse.