- reconnect
1. 1 Reasons
a. Pouring is interrupted due to various
operating failures, and reconnection defects are easily caused on the surface
of the cast slab after re-pouring.
b. Slow drawing speed results in too deep vibration marks on the surface of the cast slab, forming a reconnection.
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1.2 Control measures
a. Fully do all the preparations for
pouring steel to ensure the normal and stable pouring of steel and avoid
stop-flow accidents.
b. Ensure that the speed is normal and
reasonable.
- Inclusions and scars
2.1 Reasons for formation
a. The liquid level of the mold fluctuates
violently, so that the mold powder or other inclusions on the molten steel
level are involved in the casting slab, forming inclusions on the surface of
the casting slab.
b. The molten steel overflows at the
drawing leak and is cooled by the mold, forming defects on the surface of the
cast slab. The drawing speed fluctuates too much and frequently.
2.2 Control measures
a. Improve the technical quality and work
responsibility of the operators to ensure the stability of the crystallizer
liquid level.
b. Improve the performance of the mold
flux, increase the thickness of the molten slag layer, and increase the
absorption capacity of inclusions. Strict process operation procedures and
stable pulling speed.
d. Improve the corrosion resistance of the
tundish nozzle and plug.
- scratches
3.1 Reasons for formation
a. There is scrap steel on the foot roll of
the second cold section frame, which causes scratches on the surface of the
casting billet.
b. Uneven stretching and straightening
rolls or uneven secondary cooling will cause the cast slab to deviate, and the
cast slab will be in contact with the stretching and straightening frame and
scratch the surface of the cast.
3.2 Control measures
a. Strengthen the maintenance of the second
cold section, and find that the steel leakage should be cleaned in time.
b. Strengthen the maintenance of the
tension-straightening system to ensure the levelness of the
tension-straightening rollers, and install side guides to prevent deviation of
the casting billet.
- vibration marks
4.1 Reasons
a. Vibration marks are the inevitable
result of mold vibration and are difficult to completely eliminate. The greater
the fluctuation of the mold liquid level, the deeper the vibration marks.
b. The slower the pulling speed, the lower
the vibration frequency and the deeper the vibration mark.
C. The solidification characteristics of
steel grades have a great influence on vibration marks. Shrinkage-sensitive
steel has deep vibration marks, and crack-sensitive steel has shallow vibration
marks.
4.2 Control measures
a.Using low-amplitude, high-frequency
sinusoidal vibration.
b. Take measures to ensure the stability of
the crystallizer liquid level.
copper mould tube, continuous castng
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