Thermin powder is generally used as a mould fluxing powder for casting of ingots having larger cross section. Thermin compound when added to the meniscus of the molten slag with low melting point covering uniformly the entire surface of the meniscus so to prevent loss of heat due to radiation and oxidation of liquid steel.
Thermin forms three layers when it comes in contact with the liquid steel.
LIQUID LAYER
(Immediately in contact with the liquid steel meniscus) this gives lubrication effect between the mould and the solidifying steel shell there by farilitating easy removal of the mould.
VISCOUS LAYER
Absorbs the non metallic inclusion.
POWER LAYER
Third layer forms an insulating on the top of liquid steel.
- Thermin protects the meniscus from reoxidation as it avoids direct contact of the meniscus with air.
- Provides thermal insulation to the liquid steel there by preventing premature, solidification or skulling.
- Absorbs and dissolves nonmetallic inclusion such as deoxidation products and there by prevents their entrapment in the solidifying shell.
Thermin has good heat retaining properties in powder from it self which prevent dropping of meniscus temperature. Thermin is supplied in plastic bags. The individual weight in these bags, being depend upon the size of the ingot, can be indicated while placeing order. Packing of plastic packets are further packed in polyline gunny bags.
APPLICATION RATE
The Production per ton of ingot steel requires about 1.5 to 2 kgs of Thermin.To protect in from moisture, Thermin is supplied in plastic bags. The individual weight in these bags, being depend upon the size of the size of the ingot, can be indicated while placeing order.Packing of plastic packets are further packed in polyline gunny bags.
ADVANTGES
- Thermin does not get mixed in the liquid steel and hence the chemistry of steel remains unchanged.
- It spreads quickly and uniformly and gives adequate protection to the liquid steel meniscus.
- Thermin controlled the drop in temperature of liquid steel in the mould.
REMOVES NON METALIC INCLUSION
As scum or solid non metallic inclusion reach the slag interface, it is necessary that they should be dissolved in the slag. If they are not dissolved, they be come entrapped in the solidified steel shell.
Causing serious defects and impair the lubricating properties of the slag film between steel and mould.Alumina is formed principally by oxidation of the steel. The basicity index directly affects viscosity, solidification temperature and crystallization temperature, as well as the capability to absorb inclusion.
| THERMIN GRADES |
| PRODUCT |
STEEL GRADES |
WT. OF INGOT |
| Thermin - M |
General purpose - non Stainless steel |
< 1 Ton |
| Thermin - Ms |
General purpose - non Stainless steel |
> 1 Ton |
| Thermin - MC |
Non Stainless steel - carbon 0.4 - 0.75 |
> 1 Ton up to 18 Ton |
| Thermin - GP |
General Purpose - non Stainless steel |
> 1 Ton |
| Thermin - BSS |
Ball Bearing Steel |
> 1 Ton |
| Thermin - SS |
Stainless Steel |
> 1 Ton |
| Thermin - SSS 101 |
Ball Bearing Steel |
< 1 Ton |
| Thermin - LC |
Low Carbon steel - carbon 0.10 - 0.35 |
> 1 Ton up to 18 Ton |
| Thermin - MC |
Medium carbon steel - carbon - 0.40-0.75 |
> 1 Ton up to 18 Ton |
| Thermin - HC |
High carbon steel - 0.8 and above |
> 1 Ton up to 18 Ton |
| Thermin - RS |
Rail steels |
> 1 Ton |
