Casting Defects of Metal Materials, part 8

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

Other surface defects

Common surface defects of ingots include scars, pitting, pits, burrs, longitudinal streaks, transverse bamboo joints, etc.

(1) Roughness

Various unevenness on the surface of ingots is called roughness.

There are often granular protrusions and sand holes on the rough surface, accompanied by coatings, covering agents, oxides and other dirt.

The main reasons are low casting temperature and slow speed; the inner wall of the crystallizer is not smooth or the covering agent is poor; the funnel is blocked, etc.

(2) Burrs

The sharp metal protrusions on the surface, corners, and edges of the ingot are called burrs.

The main reasons are the rough inner wall of the crystallizer; the quality of the hollow ingot continuous casting core rod is not good.

(3) Longitudinal streaks

The continuous or intermittent longitudinal strip-shaped protrusions or depressions on the surface of the ingot are called longitudinal streaks.

The main reasons are that the inner wall of the crystallizer is drilled with metal or other oxides or grooves caused by wear; the inner lining assembly gap is large.

(4) Bamboo joints

The large periodic concave and convex phenomena on the surface of the continuous casting billet with a pull-stop process are called bamboo joints.

The main reasons are improper pulling and stopping process or deformation of the crystallizer or mold.