DESCRIPTION

MANUFACTURING METHOD FOR COMPLEX STEEL DEOXIDIZER

Subject invention is related to metallurgy field and in particular manufacturing method for complex deoxidizer that may be used for deoxidization and alloy steel to be employed in alloy steel.

By the invention, development of manufacturing method for ferrosilicoaluminum by applying the materials containing other deoxidizing items to furnace - charge composite is in question on one hand, while the mission of arranging technological melting models and heating models are involved on the other hand.

Since initially the materials with high melting temperatures have been introduced into the furnace followed by addition of aluminum, the mission pointed out has been achieved. Silica, manganese, titanium, vanadium or metals of light composition or the scraps containing combinations of these or iron alloys are used as the materials having high melting temperatures in the method expressed. Before the liquid metal is discharged into the furnace salty additives are mixed during stirring of the bath with care. In addition, when addition of aluminum involved, it is necessary to melt aluminum and heat it up to a liquid temperature above 100 to 15O ⁰ C The materials with high melting temperatures are added to molten metal as crushed parts with sizes not bigger than 20 mm after they are heated to a temperature not lower than 100 ⁰ C. During a later careful stirring stage of the melting bath, salty additive materials are added. In addition, the materials with high melting temperatures which are melted in steel melting furnace are discharged into pouring ladle full with liquid aluminum that is melted before in a renewing or neutral atmosphere by means of a gas burner.

The objective of this invention is to manufacture complex steel deoxidizers which shortens application time and ensures economical savings. The methods used to achieve this objective are explained in the examples below.

Example 1 : The materials with high melting temperatures (for example Ferro- silica, Ferrosilicon, , with melting temperature = 140 ⁰ C) are loaded into an electrical furnace ( with a capacity of 1 ton) and melted here. Then, flux of lime, silica, fluor-spat, or alum is added. After the liquid slag is removed, the furnace is closed or set to minimum load mode and aluminum is added to liquid bath.

Evacuating of furnace together with covering slag and fall of thermal load bring about aluminum residue.

After adding last aluminum parts, additive, such as NaCI with a rate of 1 % of mass of molten bath is added. The bath is stirred with care. This procedure enables an increase in the rate separating aluminum from the slag. Then, the slag is removed from the surface of bath and the molten metal is taken out of the crucible.

The results obtained during melting of complex (composite) deoxidizer in a furnace with 1 ton of capacity are presented in table 1. Table 1 - Technological indexes obtained during melting of complex (composite) deoxidizer in a furnace with 1 ton of capacity:

Practical metallic output: 85 to 90 %

Example 2: The molten materials were introduced to an induction furnace of 40 kg capacity. Aluminum AV-87 and (melting temperature = 1410 ⁰ C) 65 % ferro-silica have been used as furnace loading materials

Initially aluminum was charged into the furnace. After aluminum was melted and heated up to a degree of 750 to 800 ⁰ C, ferro-silica parts (with sizes not bigger than o 20 mm) which were previously heated up to 100 ⁰ C were added. Adding of cold and big ferro- silica parts with sizes bigger than 20 mm caused increase in melting duration.

Adding of ferro-silica parts into the furnace based on their weights were achieved in 2 to 4 steps. ( ferro- silica parts with weight up to 5 kg were added in 2 steps while ferro- silica parts heavier than 5 kg and up to 12 kg were added in four steps). These procedures cased an increase in melting time.

After the last ferro-silica parts were melted salty additives such as NaCI ( in a rate corresponding to 1 % of bath mass) were added and the bath was stirred with care. Then, the slag formed was removed and the molten metal taken. The result obtained during melting of composite (complex) deoxidizer in induction furnace with 40 kh capacity are presented in table 2

Table 2

Example 3: Iron alloys or scraps of iron alloys are loaded into the furnace and melted.

I O

The ladle to be used in melting of aluminum is above the stand. Then, internal gas burner is covered by an existing cover. Required amount of aluminum is given by special orifice. After melting of the aluminum, renewal atmosphere is created by oxygen inside gas-oxygen mixture in the amount to be spent in a

15 rate exceeding 5 to 10 % stechiometric correlation.

Technological index obtained in this condition is similar to that presented in example 1 , but lesser aluminum residue results.

20 According to technological procedures presented in examples 1 , 2 and 3 complex (composite) deoxidizers such as Al- (10-50); Si - (10-50); Mn - (0.5 -

60); V - (0.001 -20); Ti - (0.001 -20); Ce - (0.001 -10); the rest Fe (iron) having (composite and mass %) ( 2,5-6,2) g/cm ³ (density) features and melting temperature ( 900 to 1100 ⁰ C) are produced. Under the circumstances of production complex (composite) iron-aluminum-silica (FAMS) deoxidizer is used instead of aluminum pigs(masses) for deoxidization of steel in the ladle and composite iron- silica-aluminum (FSA) deoxidizer is used for covering head section of boiling steel with cork

It was detected that a correlation existed between consumption of FAMS (table 1 variant 1) and consumption of aluminum pigs (masses) while using complex deoxidizer FAMS together with variation factor (Mass share of oxygen inside metal - 0.004 to 0.005 %). Application of complex deoxidizer

FSA (table 2, variant 4 -6) reduced consumption of liquid aluminum from 0.88 kg/ ton down to 0.63 kg/ton without causing any deformation in qualitative index of metal.

Economical saving to be ensured by usage of complex deoxidizer instead of aluminum shall be 0.1 to 0.75 $/ton due to difference in prices.