I. True or False Questions.

 

 

When there are many faults in the rolling line, the furnace operator and the dispatcher need to communicate effectively and keep warm in time to avoid extending the effective heating time and thus causing decarburization. (√

 

2. If the honeycomb structure of the heating furnace is clogged, the length of the flame inside the furnace will shorten, which will result in high temperatures at both ends of the furnace and low temperatures in the middle.(√)

 

3. Before the tooling parts are put into use, there is no need to check the surface quality. (×

 

4. Regularly clean the iron oxide scale and cold steel in the rolling channel. (√

 

5. Decarburization refers to the phenomenon where the carbon content in steel decreases. In metallographic observation, it appears as white ferrite. If the entire layer is ferrite, it is a fully decarburized layer. (√

 

6. The stains on the surface of wires caused by the splashing of equipment oil or paint during storage and transportation are called storage and transportation scratches. (×

 

7. Storage and transportation scratches are caused by fuel pipe bursts from forklifts and cranes, as well as oil stains or paint floating from the periphery of the storage yard. (×

 

8. Storage and transportation rust is caused by being stored in a damp environment for too long, or being exposed to rain during storage and transportation. (√

 

9. Unless otherwise specified, all other products will be dispatched on a first-in, first-out basis.

(√

 

When the hot-rolled coil is still warm, it can be exposed to the rain on rainy days. (×

 

11. Low spinning temperature and poor water quality can cause red rust on the rolled steel. (√

 

After the roll is turned, proper protection should be taken. Rolls that are severely rusted can still be used. (×

 

13. The rough defect composed of many tiny concave and convex points on the surface of the wire is called a shrinkage cavity. (×

 

14. Before the rolls, roller rings and guide guards are put into use, the surface quality should be inspected. Those with cracks or sand holes shall not be put into use. (√

 

15. Inspect the surface of the online roller ring and the guide guard roller. If there are obvious impacts, replace them in advance. If cracks are found on the surface, they should be replaced immediately.

(√

 

 

16. At the end of the blank, a central hole can be seen. On the surface of the finished wire, an intermittent ear-shaped pattern appears. When the ear-shaped pattern is cut horizontally, a central hole can be seen. Generally, coarse grains or decarburization phenomena exist at the edge of the hole. It is called decarbonization of steelmaking. (×

 

17. The rhombic deformation at the end of the blank can be visually observed, which is also called "out-of-square". Off-square refers to the situation where one diagonal of the cast billet is less than 90° and the other diagonal is greater than 90°. The difference in the lengths of the two diagonals is called the square displacement. (√

 

18. The defect that the surface of the cast billet protrudes like a steamed bun is called double skin. The difference between the thickness of the central bulge and the edge thickness of the cast billet is called the bulge amount, which is used to measure the degree of bulge deformation of the cast billet. (×

 

19. Inclusions will not cause scabs, pits or foreign objects to be pressed in on the surface of the wire rod. In severe cases, steel will be rolled and piled up. (×

 

20. Metal sheets that are partially or completely bonded to the base material on the surface of the wire are called scabs, which are generally tongue-shaped, uneven in thickness and size. The absence of metal on the surface of the finished product, which is locally irregular, of varying sizes and has a rough bottom, is called a steelmaking pit. (√

 

Ii. Multiple Choice Questions.

 

During the steel rolling process, if the billet stays in the furnace for too long, the pressure fluctuation in the heating furnace chamber is more than three times the normal level, and the temperature difference between the head, middle and tail of the furnace is greater than 80℃, it will lead to defects. (A

 

A. Decarbonization B. Decarbonization C. Net carbon D. Folding

 

2. The following options are not the causes of carbon emissions. (D)

 

A. Uneven heating temperature leads to local areas not being fully heated or the heating temperature being too low;

 

B. Local excessively high spinning temperature leads to an increase in carbon content in the mesh.

 

C. Uneven spinning circles lead to uneven local cooling

 

D. The heating temperature of the billet is too high or the local temperature is too high

 

3. For medium and high carbon steels with high Mn and Cr content, poor cooling control during rolling can easily lead to the formation of martensite. Which of the following is not the main influencing factor? (B)

 

A. The spinning temperature is unreasonable

 

B. The temperature of the heating furnace is too high

 

C. The silk spinning is out of order or poorly centered

 

D. Unreasonable cooling and insulation systems were set up

 

4. Which of the following is not the cause of the ear shape in steel rolling? (D)

 

A. Misaligned rollers, resulting in misaligned ears

 

B. The inlet guide guard and guide wheel are worn out, the opening degree is too large or the inlet guide guard is off-center

 

C. The gap between the clamping rollers is too small. The inlet guide guard of the clamping roll deviates from the rolling centerline

 

D. The live loops have not all been put into use

 

5. The opening degree of the guide guard of the rolling mill is too large. When the rolled piece passes through the steel, its state is unstable, and the rolled piece has torsion and scratches, resulting in the finished steel being rolled. (B)

 

A. Decarburization B. Defective material C. Ear shape D. Out-of-square

 

6. Which of the following is not a measure to prevent oil stains from steel rolling? (C)

 

A. Add an oil tray to the PF line

 

B. Add oil to the PF wire chain reasonably to prevent dripping and leakage

 

C. Failing to refuel as required and reducing the frequency of refueling

 

D. Based on the oil stains on the surface of the wire, locate the corresponding oil leakage source and repair it in a timely manner

 

7. Which of the following is not the cause of steel rolling folding? (D)

 

A. The hole type is underfilled or overfilled;

 

B. Caused by poor guidance and lubrication, such as failure to align, poor surface quality or poor lubrication;

 

C. Poor control of tension and strip shape between racks

 

D. Excessive flow in the water tank

 

8. Which of the following is not a countermeasure for preventing and controlling defective materials in steel rolling? (A)

 

A. The iron oxide scale and cold steel in the rolling channel were not cleaned regularly

 

B. Before the tooling parts are put into use, the surface quality must be inspected. Only when they are qualified can they be used. Check the surface conditions of the rolls, roller rings, guide guards and roller wheels on the line

 

C. The head and tail strokes of the billet in the furnace should be consistent to ensure that the billet does not tilt or get scratched

 

When the Cu content in the billet exceeds 0.15, the boiler operator should appropriately reduce the heating temperature and air-fuel ratio to minimize the oxidation of the billet

 

9. Which of the following is not a cause of the occurrence of protrusions in steel rolling? (A)

 

A. The guide roller is stuck

 

B. The scale removal of the steel billet after heating is incomplete, and there are foreign objects on the surface

 

C. Severe wear of the rolling grooves causes the surface of the rolled piece to protrude

 

D. Cracking and meat loss of roller rings, rolls and guide guards

 

10. Which of the following is not a loose packaging control measure? (B

 

A. Set the tension reasonably, adjust the centering of the winding coil and the speed of the distributor to ensure A good ring shape

 

B. Check that the guide guards and rollers are not jammed

 

C. The pressure of the baling machine is set in accordance with the regulations

 

D. Shut down the machine for maintenance of the packaging machine

 

11. Which of the following is not a preventive measure for scratches during storage and transportation? (A)

 

A. Based on the oil stains on the surface of the wire, locate the corresponding oil leakage source and repair it in A timely manner

 

B. Forklifts should be covered with rubber hoses

 

C. The C-type hook of the crane should be fitted with a rubber hose, and the suction cup should be padded with protective material

 

D. Ensure proper fixation and protection during shipment

 

12. Which of the following is not a cause of bamboo node spots in steel rolling? (D)

 

A. Turbid water has A high oil content and poor water quality

 

B. Unstable flow and pressure in the water tank and uneven cooling of the wires

 

C. Water tank carrying water, reverse water flow, and air-blowing water cannot operate normally

 

D. Caused by excessive exposure to the sun outdoors

 

13. Which of the following is not a cause of pitted surface in steel rolling? (D)

 

A. Poor quality of the rolls, uneven surface hardness or loss of the cold hard layer

 

B. The surface of the rolled groove is uneven or severely worn

 

C. Steel adhering to the clamping roller

 

D. The water flow in the water tank is opened too much

 

Which of the following is not a cause of decarburization in steel rolling? (B)

 

A. The heating temperature of the billet is too high or the local temperature is too high

 

B. The heating temperature of the billet is too low

 

C. The heating time of the billet is too long

 

D. The decarburization layer of the middle billet in the large billet is too deep, resulting in excessive decarburization of the finished product

 

Which of the following is not a control measure for martensite in steel rolling? (A)

 

A. Reduce the rolling time

 

B. The spinning temperature shall be carried out in accordance with the process

 

C. Cut the non-cold sections at the beginning and end thoroughly

 

D. The silk spinning must not deviate and it also does not deviate on the roller conveyor

 

16. Which of the following is not a cause of poor ring shape? (B)

 

A. The filament tubes are not made in A standard manner (including weight deviation and bending accuracy).

 

B. The spinning temperature shall be carried out in accordance with the process

 

C. Wear of the filament tube; The leading amount setting of the spinning machine is unreasonable. The spinning machine is vibrating

 

D. The tension setting between fine rolling and filament spinning is unreasonable, the pressure and flow rate of the water tank are unstable, and the clamping effect of the clamping roller is poor

 

17. Which of the following is not a control measure for steel rolling marking? (A)

 

A. Leaving things unattended in order to meet production targets

 

B. Check that the guide guards and rollers are not jammed

 

C. Check the surface quality of the guide guards, guide grooves and rollers to ensure there are no burrs

 

D. Clean the foreign objects such as the guide guards, guide grooves, guide guards of the clamping rollers and the guide tubes of the spinning machine

 

18. Which of the following is not a control measure for the ear shape of steel rolling? (D)

 

A. The installation of the guide guard and the opening degree meet the requirements

 

B. Before the guide guard goes online, check that its dimensions and surface quality are qualified

 

C. Use each parking opportunity to check the wear and tear of the online guide guards. Replace them immediately if any abnormality is found

 

D. Failing to adjust the roller gap parameters of each frame in accordance with the regulations

 

19. Which of the following is not a measure for the prevention and control of carbon emissions? (A)

 

A. Reduce the heating temperature

 

B. Heat in accordance with the process regulations. The temperature difference across the entire length of the billet should be controlled within 30℃

 

C. Set the parameters of the water tank reasonably, and the length of the head without water penetration needs to be stably controlled

 

D. The spinning circle must not have piles, large circles or deviate from the site

 

Which of the following is not a preventive measure for metallographic folding? (B)

 

A. Regularly inspect the dimensions of key bars as required

 

B. Reduce the heating temperature of the heating furnace

 

C. When installing the guide guard, the alignment should be good, with three points in a straight line

 

D. Only when the surface quality of the guide guards is qualified can they be put into operation. Regularly inspect the surface quality of the online guide guards

 

Iii. Short-answer Questions.

 

During the steel rolling process, when there are defective materials in the steel rolling, please list five reasons.

 

2. During the steel rolling process, when the ring shape is not good, please list five prevention and control measures.