RU2578879C1 - Method for production of titanium-corrosion-resistant steel by electroslag remelting - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy and can be used for production of titanium-containing corrosion-resistant steels by electroslag remelting. Method involves electroslag remelting of consumable electrode in casting mold with ratio of titanium to aluminium content in electrode within 6.0-9.0, wherein content of titanium in electrode exceeds required titanium content in finished steel by value of its loss at remelting, which is defined by relationship: ΔTi=37Ti_g+35·Ti_gD²/(63+35D²), where ΔTi is average waste of titanium, obtained during melts in moulds of various section size with same duty ratio, %; Ti_g -titanium content in finished metal, %; D is diameter of crystalliser, m.

EFFECT: invention enables to obtain high-quality metal with guaranteed titanium content and with uniform distribution over volume of melted ingot.

1 cl, 5 tbl

Description

The invention relates to special electrometallurgy, specifically to the production of ingots of stainless titanium-containing steel grades by the ESR method, and can be used to produce titanium-containing highly alloyed corrosion-resistant steel grades by electroslag remelting.

A known electrode for ESR of titanium-containing corrosion-resistant steel grades containing titanium in an amount equal to its content in the finished metal, during remelting of which, to maintain the normalized titanium content in the finished metal, remelting is performed on a flux containing TiO ₂ or in a protective argon atmosphere or during the remelting process, flux is deoxidized with deoxidizing powders through a dispenser. [one]

The disadvantages of the consumable electrode are the need for additional equipment for remelting, uneven in height and cross-section of the ingot, and unwarranted titanium content.

As a prototype, a consumable electrode for ESR of corrosion-resistant titanium-containing steel grades containing titanium 0.15% closer to the upper limit or higher is used for the remelting of which ANF-6 flux with 1% titanium sponge is used for remelting , and additionally, during the remelting process, flux is deoxidized with aluminum powder in an amount of 0.5 kg / t. [2, 3]

The disadvantages of using this electrode for ESR are the need for additional equipment during remelting, the danger of transition of aluminum to metal, which increases brittleness and reduces the resistance of metal to corrosion, unwarranted and uneven content of titanium in height and cross-section of the ingot, which does not ensure reliable metal quality.

The objective of the invention is to obtain a consumable electrode that provides high-quality metal with a guaranteed titanium content and its uniform distribution over the volume of the ESR ingot.

The essence of the invention lies in the fact that the consumable electrode contains titanium higher than that required in the finished steel by the value of its fume during remelting, determined by the formula

ΔTi = 37Ti _g + 35 · Ti _g D ² / (63 + 35D ² ),

where ΔTi is the average waste of titanium,%,

Ti _g - titanium content in the finished metal,%,

D is the diameter of the mold, m,

while the ratio of titanium to aluminum should be in the range of 6.0-9.0.

It is known that in the process of remelting, titanium partially oxidizes, passing into flux. Burnout of titanium depends on many factors.

In studies conducted at the Zlatoust Electrometallurgical Plant, the dependence of titanium fume on the ratio of titanium and aluminum in the electrode, on its content in the finished metal, and on the area of contact of the liquid flux with the gas phase (on the area of the gap between the mold and the consumable electrode) during remelting is examined .

The dependence of titanium fume on the ratio of titanium to aluminum in the starting metal (electrode) is obtained for the same titanium content in the metal of the electrode. The experimental data for the electrode kr.445 mm during remelting in the crystallizer kr.630 mm are given in table 1.

When the ratio Ti / Al in the metal of the electrode is more than 9.0, the carbon loss of titanium increases significantly.

When the ratio Ti / Al is less than 6.0, the consumption of aluminum increases, and the loss of titanium decreases slightly.

The ratio of Ti / Al from 6.0 to 9.0 is optimal

According to the results of studies obtained during the experimental melting of ESR into crystallizers of different profile sizes, but with the same fill factor of the mold (the ratio of the cross-sectional area of the electrode and mold, table 2), on flux ANF-6 and with a ratio of titanium to aluminum 6.0-9, 0, an empirical formula is obtained for the dependence of titanium fume on its content in the finished metal and on the diameter of the mold.

ΔTi = 37Ti _g + 35 · Ti _g D ² / (63 + 35D ² ),

where ΔTi is the average waste of titanium,%,

Ti _g - titanium content in the finished metal,%,

D is the diameter of the mold, m

The average burn-off of titanium was calculated during the remelting of steel grade 08X18H10T on an electroslag furnace in crystallizers kr.630, kr.500, kv.390 (it corresponds to a round mold kr.440 mm).

The experimental and calculated data on the loss of titanium in the process of remelting steel grade 08X18H10T-Sh are shown in table 3.

To calculate the limits of the titanium content in the starting metal, we accept the requirements of the lower limit for the ESR metal by 0.1% more, and the upper one - 0.1% less for guaranteed falling into the normalized limits, since Titanium fume was considered average.

The calculation results are shown in table 4.

The calculated data are in good agreement with the requirements obtained from practice at the Zlatoust electrometallurgical plant.

If the titanium content in the source metal (electrode) is higher than the calculated value in ESR ingots, it will be higher than the upper limit of its normalized content.

When the titanium content in the source metal is lower than the calculated in the ESR ingots, it will be below the lower limit of its normalized content.

According to the calculated data, 10 melts of the initial metal of each steel grade were smelted, which were remelted for ESR. The titanium content on all melts meets the requirements for the finished metal and is equally high and the cross section of the ingots (table 5).

Using the proposed consumable electrode for ESR allows you to get high-quality metal with a guaranteed titanium content and with its uniform distribution over the volume of the ingot.

Information sources

1. A.G. Glebov, E.I. Moshkevich. Electroslag remelting. - M.: Metallurgy, p. 246, 247.

2. S.A. Leibenzon, A.F. Tregubenko. Steel production by electroslag remelting. Metallurgizdat, 1962, Ch. 13.

3. A collection of technological instructions for electroslag and vacuum-arc remelting. Dneprospetsstal plant.

Claims (1)

A method for the production of titanium-containing corrosion-resistant steel by electroslag remelting of a consumable electrode in a mold, characterized in that the consumable electrode is remelted with a ratio of titanium to aluminum in the range of 6.0-9.0, while the titanium content in the electrode exceeds the required titanium content in finished steel by the value of its fume during remelting, which is determined by the dependence: ΔTi = 37Ti _g + 35 · Ti _g D ² / (63 + 35D ² ),
where ΔTi is the average waste of titanium obtained by conducting melts into crystallizers of different profile sizes with the same fill factor,%;
Ti _g - titanium content in the finished metal,%;
D is the diameter of the mold, m