What are the types of sheet and strip process wastes and their causes?

1. Through pores Poor casting quality.

2. The surface bubble ingot has high hydrogen content and loose structure; the uneven surface of the ingot has a dirty surface, which was not cleaned before loading the furnace; after etching, the surface of the ingot and the aluminum-clad plate has residual traces of etching and washing; the heating time is too long Or the temperature is too high, the surface of the ingot is oxidized; during the first welding and rolling, the emulsion nozzle is not closed tightly, and the emulsion flows under the aluminum-clad plate.

3. Ingot cracking When the reduction amount is too large during hot rolling, the end of the ingot is cracked; the heating temperature of the ingot is too high or too low.

4. The mechanical properties are unqualified, the heat treatment system is not implemented correctly or the heat treatment equipment is abnormal, and the air circulation is not good; the quenching batch is large, the temperature of the salt bath is not enough for the furnace, the holding time is insufficient, and the furnace is released before reaching the specified temperature; the heat treatment system adopted in the laboratory Or the test method is incorrect; the shape of the sample is incorrect, and the surface of the sample is damaged.

5. Slag inclusion in ingot The casting quality is not good, and there are metal or non-metal residues in the plate.

6. The composition of tearing lubricating oil is unqualified or the emulsion is too thick, slippage occurs between the plate and the roll, and the metal deformation is uneven; the rolling rate is not well controlled, and the reduction is too large; the rolling speed is too large; the roll tension is not adjusted properly Correct, the tension is unstable; the annealing quality is not good; the metal plasticity is not enough; the roll shape control is not correct, so that the metal internal stress is too large; the hot-rolled coil is cracked; If the coil is not fed correctly, the strip produces tensile stress and compressive stress at the same time, causing small cracks on the edge. After rolling for many times, it will continue to expand from the crack and even tear; during finishing, the jaws of the stretching machine are not properly clamped. Or uneven, or the plate has cracked edges, which will cause tearing when stretched; during quenching, the pocket chain is not well or too tight, which will fracturing the plate and cause tearing when stretching and straightening.

7. Too thin Incorrect adjustment of the reduction; malfunction or improper use of the thickness gauge; incorrect roll shape control.

8. Pressing and folding (folding) The roll shape is incorrect. For example, the bearing of the calendering machine is heated, which causes the two ends of the rolling roll to expand. As a result, the extruded sheet is thick in the middle and thin on both sides; Thus, folds are produced; when the sheet is calendered, it is easy to cause folds when the feeding is not correct; the thickness difference between the two sides of the plate is large, which is easy to produce folds.

9. The non-metallic rolls, roller table, scissors, etc. that are pressed into the hot rolling mill are not clean, and the dirt falls on the flat car belt during processing, and is formed by rolling; the rolls, guide rolls and three-rollers of the cold rolling mill are straightened The parts contacting the strip such as the machine and coiler are not clean, and the dirt is pressed in; the rolling oil nozzle is blocked or the pressure is low, and the non-metallic dirt adhering to the surface of the strip cannot be washed away; the emulsion is not replaced in time, The aluminum powder was not washed cleanly and the lotion tank was not washed cleanly.

10. The high-temperature instrument of the over-burning heat treatment equipment is inaccurate; the temperature of each area of ​​the electric furnace is uneven; the heat treatment system is not implemented correctly, and the metal heating temperature reaches or exceeds the metal over-burning temperature; the charging is not placed correctly, and local over-burning may occur near the heater .