4.7 t ingot made of 18Kh2N4VA steel

4.7 t ingot made of 18Kh2N4VA steel - Ingot defects

Figure 1: 4.7 t ingot made of 18Kh2N4VA steel.

Figure 2: Dark shell in a 4.7 t ingot made of 18Kh2N4VA steel.

Defect name: No data.
Record No.: 3342
Type of defect (Internal/Surface): Surface
Defect classification: Ingot defects
Steel name: 18Kh2N4VA steel
Steel composition in weight %: No data.
Note: The problems related to improving the process of top casting of complexly alloyed and high.alloy steels and alloys are considered. To increase the ingot surface quality and the ingot.to.product yield, a new method of top casting of steels and alloys is proposed. In this method, a floating shield made of a light refrac. tory material is placed in a mold and protects the mold surface against metal splashes.

The first experiments of casting 18Kh2N4VA steel into 4.7 t ingots performed with this technique showed that the ingot surface is defectless (Fig. 1) and that a dark shell forms upon rolling (Fig. 2).
This shell results from the fact that some drops stuck to the inner shield walls to form a shell during casting; this shell left the shield, penetrated into the metal volume, and had no time to dissolve completely.
To remove this shell, we preliminarily deposited an antistick coating made of a mixture of 85% graphite and 15% clay onto the inner shield surface in order to prevent sticking of metal drops to the inner shield sur. face and their penetration into the ingot body, which was supported upon rolling of ingots. No defects in the ready products were detected.
Another advantage of this casting method consists in the fact that the shield occupying the upper position serves as an additional heat.insulating gasket that allows a metal to be held in the liquid state in the sink. head for a longer time, which decreases the number of shrinkage defects.

In conclusion, note that it was easy to implement this technology of top casting of high.alloy steel into a mold with a protective shield. This technology makes it possible to produce ingots with a good sur. face, which excludes the costs of its conditioning, and the decrease in the heat removal from the head of the ingot leads to a decrease in the cutting losses by 3–5%.
Reference: Not shown in this demonstration version.