SU1255645A1 - Steel deoxidation method - Google Patents

Description

The invention relates to the metallurgy of the foundry industry, in particular to the deoxidation of heat-resistant steels intended for casting machine parts and apparatus operating under conditions of long-term loading at temperatures up to 600 C.

The aim of the invention is to increase the long-term strength of heat-resistant steels.

The goal is achieved by the fact that the steel is preliminarily deoxidized with aluminum together with ferrotitanium and silicocalcium in a furnace before the formation of refining slag in the amount of 0.5-0.8, 2-3 and 1-3 kg / t, respectively. After the refining slag has been melted and processed by reducing mixtures, ferromanganese and

ferrosilicon in the usual order of the 20th to produce pure steel without having to obtain the average grade of manganese and silicon in the steel. In the event of an aluminum injection in the amount of 0.1-0.5 kg / ton is additionally introduced into the ladle.

tallic inclusions with residual; aluminum content or total aluminum and titanium content less than 0.03%, which provides the most

on the basis of obtaining a residual amount of 25 full implementation of the mechanism of dispersion 40

content of aluminum and titanium

in steel no more than 0.03%.

Preliminary deoxidation of steel is STRONG deoxidizing agents (aluminum together with ferrotitanium and silico-ZO

This ensures a sharp decrease in the oxygen content in the metal before refining, which allows to obtain

cleaner steel in terms of non-metaplich inclusion,

At the same time, the deoxidation of steel: with aluminum, ferrotitanium, and silico-calcium in the specified amounts contributes to an increase in the degree of deoxidation of molten steel. Consumption of aluminum, ferrotitanium and silicocalcium less than 0.5 | 2 and 1 kg / ton, respectively, depending on the amount of oxidized carbon, may be insufficient for complete deoxidation of molten steel. Consumption of aluminum, ferrotitanium and silicocalcium more than 0.8, 3 and 3 kg / t, respectively, is not economically feasible. In addition, when early introduction of strong deoxidants (aluminum, titanium) into the furnace by the time of their release, their total content in the metal is significantly less than 0.03%, which is a necessary condition for the nitride hardening mechanism to be fully implemented in steel. With the consumption of aluminum, ferrotitanium and silicon, calcium is greater than 0.8, 3 and 3 kg / tonne, 45

50

2556452

Responsibly, the total content of aluminum and titanium in the metal at the time of release may exceed 0.03%. In this case, the cosmS in the finished metal is given thermodynamic conditions for the formation of titanium and aluminum nitrides due to their higher affinity for nitrogen compared to vanadium. With the release of an additional input

W aluminum in an amount of 0.1-0.5 kg / t to prevent the effect of secondary oxidation of steel during casting. Entering aluminum less than 0.1 kg / ton is not effective enough. When aluminum is introduced more than 0.5 kg / t, its residual content may exceed 0.03%,

The analysis shows that the implementation of the proposed method of steel deoxidation creates conditions

to get steel clean

tallic inclusions with residual; aluminum content or total aluminum and titanium content less than 0.03%, which provides the most

Zionic hardening with vanadium di-nitrides,

In this case, the proc. The stability of heat-resistant steel is significantly higher than with a residual aluminum content in it or a total aluminum and titanium content of more than 0.03%.

The method is carried out as follows.

When smelting heat-resistant steel in the DS-5M electric arc furnace, the main process after conducting the oxidation period and removing the oxidizing slag is deoxidizing the bath with aluminum together with ferrotitanium and silicocalcium and setting the slag mixture. The consumption of deoxidizers is established depending on the amount of oxidized carbon. After penetration of the pshak and its treatment with reducing mixtures, ferromanganese and ferrosilicon are injected into the furnace at the rate of obtaining a given grade composition. With the release of aluminum in addition to the ladle at the rate of obtaining the residual aluminum content in the steel is not more than 0.03%.

Example 1. After removal of the oxidizing slag, kg / t is introduced into the furnace: aluminum 0.5; 28% ferro-titanium 2.0; silicocalcium, 0, pos .31

jie impurities and the smelting of slag are introduced into the furnace by ferromanganese and ferrosilicon for their average grade content in steel, and in the ladle at the outlet - 0.1 kg / ton of aluminum.

The residual content of aluminum and titanium in the steel was 0.01 and 0.001%, respectively. The amount of oxidizing carbon is 0.15%.

PRI me R. 2. After removal of the oxidizing slag, kg / t was introduced into the furnace: aluminum 0.7; ferrotitanium 2.5; silicocalcium 1,5. After laying and melting the slag, ferromanganese and ferrosilicon are introduced into the furnace for their average grade content in steel and 0.3 kg / ton of aluminum in the ladle at the output.

The residual aluminum content and

titanium in steel is 0.0172 and 0.006%, respectively. The amount of oxidized carbon is 0.25%.

Example 3. After removal of the oxidative stock, kg / t was introduced into the furnace: aluminum 0.8; ferrotitanium 3.0; silicicocci 3.0. After laying and melting the slag, ferromanganese and ferrosilicon are introduced into the furnace for their average grade content in steel, and in the ladle at the outlet - 0.5 kg / ton of aluminum.

Proposed 1

2

3 Lime

0,210,420,45,5,270,0240,019

0,220,480,395,170,0280,022

0,200,360,475,640,0190,017

0,210,500,425,30: B, 022,0,021

556454.

The residual content of aluminum and titanium in the steel is 0.020 and 0.009%, respectively. The amount of oxidized. carbon 0.3%.

5 When steel is deoxidized by a known method, 0.3 kg / ton is introduced into the furnace. aluminum and 1 kg / ton of 28% ferrotite, and in the ladle 0.35 kg / ton of alcmini in the sequence determined by 10 known deoxidation methods.

The residual content of alnmini and titanium is 0.035 and 0.012%, respectively.

The chemical compositions of steels, which have been diluted according to the proposed method (1-3) and according to the known (4), and their mechanical structures are given in Table. 1 and 2.

As can be seen from the table. 1 and 2, when deoxidizing cast heat-resistant steel containing nitrogen and vanadium, the proposed method provides a significant increase in the limit of long-term strength compared to deoxidation of this steel by the known (while maintaining the other properties at the same level). -.

The use of the proposed method will improve the reliability and durability of castings from steel containing nitrogen and vanadium.

Table 1

0,110,014

0,100,012

0,120,013

0.09 OjOll

Go stavitel M. irib Avkin Editor S. Gunko; Tehred L.Oleinik

Order 4786/29 Circulation 552Subscription

VNIIPI USSR State Committee

on grandfathers of inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, Projecto st., 4

Table 2

Proof-reader I.Erdeyi

Claims (1)

METHOD OF STEEL BASED ON STEEL, including deoxidation of metal in the furnace with lump aluminum and ferrotitanium and deoxidation in the ladle during the release of lump aluminum in an amount of 0.1-0.5 kg / t of steel, which requires that, in order to increase the long-term strength of heat-resistant steels containing nitrogen and vanadium, aluminum is introduced into the furnace together with ferrotitanium and silicocalcium in an amount of 0.5-0.8, 2-3 and 1-3 kg / t, respectively, until the formation of refining slag. 1 1255645