SU1191171A1 - Steel-casting process - Google Patents

Description

The invention relates to metallurgy, in particular to the production

multilayer ingots.

The purpose of the invention is to reduce the level of chemical and physical non-one-sidedness and reduce the duration of the ingot solidification.

This goal is achieved by the fact that the melt is poured into the tank at a temperature of 135-200 ° C above · 'θ of its liquidus temperature, purging with an inert gas is carried out for 0.2-302! the duration of the solidification of the ingot at a pressure of 1.5-3.0 atm, and the introduction of the alloying alloy is carried out with a temperature of 60-100 ° C above the liquidus temperature of the molten melt while simultaneously purging with an inert gas at a pressure of 0.7-1.4 atm. . ²⁰

In the production of multilayer slugs according to the method — the prototype, the perturbation of the alloying alloy is 120–180 ° C higher than the melt liquidus temperature, which causes the partial or complete melting of the metal layer hardened by the time of introduction of the alloy, increases. the duration of the ingot solidification and increases its level of 30 physico-chemical heterogeneity.

In the proposed method, the temperature of the cast alloy is noticeably lower and the development of these processes is practically eliminated or is very difficult. The rate of solidification in this case is higher, and the degree of physical and chemical heterogeneity of the internal volumes of the ingot significantly decreases. 40

The limits of variation of the pouring temperature and the melt blowdown time with an inert gas (135–200 ° C above its liquidus temperature and 0.2–30% of the solidification time are 45 ka, respectively) are set on the basis of the experiments performed and are optimal for providing the required thickness hard shell ingot accelerated by its 50

solidification from the walls to the center of the mold and the minimum degree of physico-chemical heterogeneity of steel that crystallizes after dissolving the liquid alloy 55

alloy.

The proposed casting interval of the alloying alloy (60-100 ° C above

liquidus melted temperature) was also established on the basis of experiments. Filling the alloying alloy at a temperature above the liquidus temperature of the melt by more than 100 ° C leads to a partial melting of the solidified. the primary metal in the ingot Ή increases the total time of its hardening with a significant development of chemical heterogeneity of steel. Filling the alloy at temperatures below the liquidus temperature by more than 60 ° C does not ensure sufficient mixing of the steel components in the internal volumes of the ingot and causes the formation of defects of shrinkage and segregation origin.

The proposed method can be used to produce multilayer ingots of any composition.

Example.' It is necessary to obtain an ShH15SG steel ingot with a carbon content of 0.45% in the shell of the same steel with carbon of 0.75% (liquidus temperature 1440 ° С). The thickness of the shell layer of the ingot should be within 40 ± 5 mm, the mass of the ingot is 2.7 tons. To obtain a given shell thickness, purging with argon of the primary metal must be carried out for ~ 9 min, which is about 10% of the time of complete solidification of the ingot 550 · 550 mm (85 min) determined according to the well-known formula of the parabolic solidification law.

The original metal was smelted in open arc 10-ton furnaces.

In one furnace, steel type 111X15 with a carbon content of 0.75% was smelted, in the other - with carbon 0.03%. The primary metal was poured into the mold from above to the level of its joint with the profitable extension at 1580 ° C and the metal was blown with argon (P = 2 atm) for 9 minutes through a porous plug of refractory mass inserted into the bottom of the mold. After that, the profitable part was filled with molten steel of the type ХШ15СГ with carbon of 0.03% at 1540 ^ 0 and the blowdown was continued for another 20 min at an argon pressure of 1.0 atm.

In parallel, produced a multilayer ingot according to the method prototype.

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The cutting parameters of metal treatment with gas during solidification did not change, but steel of type SHH15SG with 0.75% carbon was poured at 1560 ° С, and

the profitable part was filled with melt. five

ShH15SG type steel with carbon 0.03% at 1600 ° С.

The gas pressure at the outlet of the gearbox as the filling of the molds · gradually increased from 0.1 to 2 atm .. 10

Redistribution of ingots produced by rolling. The metal was studied in the deformed state.

The results of the study of the quality of the metal of the bimetallic system, - 15 obtained by casting steel according to the methods proposed and the prototype, are given in table. 1 and 2.

Investigated the quality of ingots of a similar composition, but manufactured under conditions that satisfy the upper and lower limits of the values of the parameters indicated

Preform macrostructures

body parts with

14

in the invention of the th not satisfying them. ,

The parameters of the metal casting and the results of the study of the quality of the metal are given in Table 3

The results of the research show the advantages of the proposed method of steel casting: the quality of the metal macrostructure increases, the heterogeneity of the distribution of alloying elements and the total solidification time of ingots are reduced by 6-10%. The method is simple to implement and ensures good welding of the layers over the entire boundary and the compliance of the thickness of the shell of the hardened ingot to its specified value, calculated using known formulas. The use of the proposed method of casting to increase the technological plasticity of steel grades at ZMZ will allow to obtain an economic effect of 22 rubles / ton of suitable ingots.

Table 1

220x220 mm their top

Way

casting

Evaluation of macrostructure defects, score

Central Pinpoint non- Spotty Layered Newest day homogeneous segregation crisst allycation rustiness ness

Prototype 2.5

Proposed 1.5

2.0

Not

2.5

1.5

2.0

0.5

$

1191171

b

' Table 2

Chemical composition, I, over the section of the workpiece 220 * 220 mm

Chemistry element Cover edge Primary metal on border with internal by layer Secondary metal on. border with outdoor by layer Work Center WITH 0.76 0.70 0.46 0.44 0.76 0.74 0.46 0.46 Mp 1.03 1.02 1.05 1.06 1.14 1.14 1.15 1.15 5Ϊ 0.63 0.61 0.59 0.60 0.61 0.60 0.62 0.62 R 0.0.14 0.014 0.015 0.014 0.014 . 0.015 0.016 0,017 five 0,009 0,008 . 0,008 0,008 0.011 0.012 0.012 0.014 Νί 0.30 0.32 0.30. 0.32 0.29 0.29 0.28 0.28 Cr 1.52 ϊ, 50 1.52 1.51 1.49 1.50 1.50 1.50 Si 0.22 0.24 0.24 0.22 0.14 0.14 0.16 0.16 Moe 0.11 ' 0.11 0.11. • 0.10 0.10 0.10 0.10 0.10 N 0,009 0,010 0,010 0,010 0,010 0,010 0.01 ¹ 0.011 0 0,0030 0,0036 0,0036 0,0040 0,0025 0,0028 0,0029 0,0030

Note: In the numerator - the results of the analysis of the metal of the ingot,

prototype cast, denominator according to invention. The error in the determination of oxygen + 10 ~ 4ζ, nitrogen ± 10 ~ 3%.

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1191171

eight

- · Table 3

Evaluation of defects in the macrostructure of workpieces 220 "220 mm

Way Overheat Time Overheat spill over the blowing alloy ki peratu ki ras- over the swarm water peratu vidus % of swarm melt of time vidus with his hardened melt casting devanias ° s ingot

Macro structure defects

Central Dot Friday- Layer- Newest day Naya taya lika Naya crystal rustiness heterogeneity vacation licensing

Proposed 120

135

170

200

210

210

Prototype 120

0.1 50 0.2 60 sixteen 80 thirty 100 32 110 32 50 10.6 160

3.0 2.0

1.5 No

1.0 No

1.0 No

1.5 1.5

2.5 2.0

2.5 2.0

2.0. 2.0

1.5 0.5

1.0 No

1.0 No

1.5 1.0

2.0 2.0

2.5 ’2.0

Note: With all the tested variants, the steel was cast into ingots with a mass of 2.7 tons, the primary metal was blown with argon under an overpressure of 3 atm, after the introduction of the alloy, the overpressure of the gas was reduced to 1 atm ^

before and after casting alloy 29 min.

Claims (2)

STEEL CASTING METHOD for producing multilayer ingots, including pouring the melt into the tank, blowing it with an inert gas with a pressure of 1.5-3.0 atm, the introduction of a liquid alloying alloy with simultaneous purging with an inert gas at a pressure of 0.7-1.4 atm, characterized in that СhТ04 in order to reduce the level of chemical and physical heterogeneity and reduce the duration of solidification of the ingot, the melt is poured at a temperature of 135–200 ^p C above its liquidus temperature, and the melt is purged with an inert gas for 0.2– 30 ^ duration. solidification of the ingot, and the introduction of the alloying alloy is carried out. § with a temperature of 60-100 ° C above the liquidus temperature of the molten melt. δ and „ί191171 > one 1191171 2