What are the main physical and chemical properties of continuous casting powder?

(1) Chemical composition:

The chemical composition of each grade of protective slag should be analyzed. The content of each oxide should be within the specified range. This is the minimum index.

(2) Melting temperature:

The slag powder is made into a 3x5mm sample, and the sample is heated to the temperature at which the cylinder becomes a hemispherical shape on a special instrument. The temperature at the hemispherical point is defined as the melting temperature.

(3) Viscosity:

It indicates the fluidity of molten slag powder into liquid. The fluidity of slag has an important effect on the absorption of inclusions and the lubrication effect of billet shell. Usually, the viscosity of slag at 1300℃ is measured by torsion pendulum viscometer or rotary viscometer to compare the fluidity of different slag.

(4) Melting speed:

Melting speed is to measure the speed of slag melting process; It is related to whether a stable three-layer structure can be formed on the molten steel surface of the mould and the required thickness of the liquid slag layer.

The melting rate may be expressed as the time required for a standard specimen to completely melt into a liquid at a specified temperature (e.g., 1300℃ or 1400℃). It can also be expressed by a certain weight of protective slag powder, heated to a specified temperature, and the amount of liquid slag formed per unit area and time.

(5) Spreading:

It represents the covering ability and uniformity of the powder slag added to the molten steel surface. Can be used in a certain volume of the protective slag powder, from the specified height down to the spread of the flat surface area to measure.

(6) Moisture

Protective slag powder absorbs moisture easily. The adsorption water component exceeds the specified requirements (such as 0.5%), the slag powder will agglomerate, endangering the use effect.