SU1260108A1 - Method of producing large-size steel casting - Google Patents

Abstract

The invention relates to the field of foundry, in particular, to the processing of melt in the liquid state in a mold using chemical methods of influence on the surface layer of the casting. The purpose of the invention is to improve the quality of steel casting. Improving the quality of the steel casting is achieved by the fact that, after topping up, a layer of iron oxides is fed to the metal surface in the profitable part of the mold of the liquid steel and the thermal insulator is introduced after the iron oxide layer is melted. By the time of refilling the first batch of liquid steel into the casting mold, the thickness of the hardened steel layer increases with a simultaneous increase in the carbon content in the remaining steel volume. 2 tab. I (L ts9 Od

Description

t

The invention relates to a foundry, in particular, to the processing of a melt in a liquid state in a mold using chemical methods of action on the surface layer of a casting.

The purpose of the invention is to improve the quality of steel casting.

The method for producing a large steel casting is carried out with the following sequence of operations: pouring molten steel into the casting mold; topping up in the near part of the mold of liquid steel in portions with gradually decreasing carbon content; after each portioned addition, a layer of iron oxides is fed into the mold of liquid steel in a mold; melting of a layer of iron oxides; . After melting the oxide layer, the jelly induces a heat insulator layer.

Example 1. When producing a casting with a weight of 100 tons, liquid steel grade 25L is poured into the casting mold and a 100 mm thick heat insulator layer, the lower half of which is pearlite, and the upper part asbestos crumb are applied to the surface of the heat insulator. .

After 10 hours, the first refill of the 20L liquid steel was made through the sprue to the near part of the casting mold, and the thermal insulator layer induced during the pouring of the main oil of the liquid steel was removed. A layer of iron oxide 50 mm thick is applied to the mirror of liquid steel in the profitable part of the casting mold. After melting, a layer of heat insulator 100 mm THICKNESS is applied, the lower half of which is perlite and the upper asbestos crumb I

6 hours after the first refilling in

Near the lower part of the casting mold, through the lithic operation, the second refill is made of 15L liquid steel and the heat insulator layer induced after the first refilling is removed. In the profitable part of the casting mold, a 50-mm-thick layer of iron oxides is placed on the mirror of liquid steel. After melting it, a layer of thermal insulator with a thickness of 100 MMj leads the lower half of the core to perlite and the asbestos cropps.

10 hours after the second refill in the profitable part of the mold

08.2

the third refill of liquid UL grade steel is performed and the same work is performed as after the second refilling.

As iron oxides use FeO,

Comparative data and quality indicators for using the known and proposed methods for producing 100-ton castings of the type of work are given in Table. one,

Table 1

Indicators

Way

Lime

Proposed

s

25L

20L

25L.

20L

15L 15L YOU LE

38

38

1.1 0.4

They have - Defek - from children there are no deep crack cracks.

Example 2. Upon receipt of a casting with a weight of 150 tons, liquid steel of 25L type is poured into the casting mold and a layer of heat insulator 120 mm thick is put on its surface in the profitable part, the bottom steel sheet

the fault of which is perlite, and the top one - asbestos chips.

After 12 hours, the first refill of 20L liquid steel was made through the sprue into the profitable part of the casting mold and the thermal insulator layer induced by pouring the main mass of the liquid steel was removed. On the mirror liquid

steel in the profitable part of the mold serves a layer of iron oxides with a thickness of 60 mm, after melting of which a layer of heat insulator 120 mm thick is applied, the lower half of which is perlite, and the upper half is asbestos crumb

10 hours after the first refilling, the 15L liquid steel was refilled through the sprue to the profitable part of the casting mold and the thermal insulator layer induced after the first refilling was removed. A layer of iron oxides with a thickness of 60 mm is applied to the mirror of liquid steel in the profitable part of the casting mold, after melting it is induced, a heat insulator layer with a thickness of 120 mm, the bottom half of which is perlite, and the upper layer is asbestos crumb.

10.h after the second refill, the third refill of liquid 10L grade steel is made through the sprue to the profitable part of the casting mold and the same work is done as after the second

LIZKI.

12 hours after the third topping into the near part of the casting mold, a fourth refill of liquid UL grade steel was performed and the same work was done as after the third topping up.

As iron oxides use FeO.

Comparative data and quality indicators for using known and proposed methods for producing 150-ton castings of the type of work are given in Table. 2,

table 2

Mark the bulk of the liquid steel

Brand of liquid steel

first topping up

Brand of liquid steel

second topping up

Brand of liquid steel

third refill

Continuation of table 2

-

YuL

50

YuL

50

1.25 0.45

Defek defects are not of the type of deep cracks

B result of the fact that after each batch topping up the mirror of liquid steel in the profitable part of the mold serves a layer of iron oxides, they are melted with. decomposition into iron and oxygen. Iron is converted to molten steel, and oxygen is mainly used to oxidize carbon, which accumulates in excess in the profitable part of the casting. The oxidation of carbon produces CO and CO gases, which are derived from the profitable part of the casting. As a result, the carbon content in the liquid steel of the profitable part of the casting is reduced. When making gaseous. the oxidation reaction products stir the liquid steel, because the released volume of gaseous products many times exceeds the volume of the liquid steel. .

The purpose of the heat insulator layer in the proposed method is the same as in the well-known one. The difference of the invention is the sequence of actions, namely, that

the heat insulator layer is made after the iron oxide layer melts, and not immediately after topping up, the liquid steel. This feature is significant because the deposition of a thermal insulator layer before the iron oxide layer melts leads to a mixture of iron oxides and a thermal insulator, which reduces the effectiveness of iron oxides in reducing the carbon content in the profitable part of the casting.

Feeding a layer of iron oxides to the mirror of liquid steel after each batch topping up liquid steel is also an essential feature. The solidification of the liquid steel from the surface of the casting mold begins predominantly with the same composition of carbon that was obtained by extruding the liquid steel from the metallurgical furnace, i.e. With this, carbon segregation is not observed. By the time of refilling the first portion of the liquid steel in the mold, the thickness of the hardened layer

12601086

the steel increases with simultaneous carbon content in the remaining volume of the liquid steel, and before each subsequent batch topping up the volume of the liquid steel in the mold decreases and the carbon content in this volume increases.

Claims (1)

10 claims The method of obtaining a large steel casting, including pouring of liquid steel into the casting mold, refilling in 5, the profitable part of the metal mold in portions with gradually decreasing carbon content, and then the introduction of a thermal insulator, characterized in that 20. Improving the quality of the steel casting, after topping up, in a profitable part of the mold, portions of liquid steel are poured onto the metal mirror in the near part of the casting mold, a layer of iron oxides, and 25, the heat insulator is introduced after the iron oxide layer melts. Compiled by I. Zhurin Editor E, Kopcha Tekhred L. Serdyukova Proofreaders. Sharoshi 5164/7 Circulation 757 Subscription VNISh USSR State Committee for inventions and discoveries PZAZZ, Moscow, Zh-35, Raushsk nab., d. 4/5 Production and printing company, Uzhgorod, st. Project, 4 The method of obtaining a large steel casting, including pouring of liquid steel into the casting mold, refilling in the profitable part of the metal casting in portions with gradually decreasing carbon content, and then the introduction of a thermal insulator, characterized in that Increasing the quality of the steel casting, after topping up, in a profitable part of the shape of a portion of liquid steel, a layer of iron oxides is fed to the near part of the mold, and the heat insulator is introduced after the iron oxide layer melts.