Casting Defects of Metal Materials, part 7

The main defects of casting products are segregation, pores, shrinkage and shrinkage, inclusions, cracks, cold shut and other defects.

Grain Unevenness

The phenomenon of large differences in grain size in different parts of the ingot is called grain unevenness.

Common ones include: the center line of the flat ingot crystallization deviates from the center, the coarse columnar crystals on both sides, the direction difference is large, the columnar crystals are twisted, and the direction is disordered; the round ingot is seriously eccentric, the local coarse columnar crystals, the local grains are small; suspended crystals or other abnormally coarse grains.

The main reasons for the occurrence: the inner wall of the crystallizer is rough, the crystallizer is deformed, and the lubricating oil coating is unevenly distributed; the cooling intensity varies greatly, the cooling water flow is uneven, the injection angle is unreasonable, and the direction is disordered; the casting time is long, the pouring temperature is low, and the cooling is slow.