SU1640174A1 - Method of cast iron modification - Google Patents

Abstract

The invention relates to foundry and can be used in iron foundries when casting molds by means of automatic casting plants based on induction furnaces. The purpose of the invention is to reduce the consumption of a modifier by reducing its unproductive losses. The method involves feeding the Powdered Modifier with a gas-powder jet into a jet of liquid metal, while the gas-powder jet is directed at an angle of 20-70 ° C. to the axis of the jet of liquid metal with a linear velocity of 3-15 m / s. The introduction of a gas-powder jet into the metal jet with the specified parameters ensures a reduction in the modifier consumption by 16.7–30.5%, a reduction in the chaff of the wedge sample by 16.7–36.7% due to a change in the shape of the gas-powder jet and the conditions of its contact with the metal. 1 tab.

Description

The invention relates to foundry, in particular, to methods for modifying pig iron by injecting a finely granulated or finely divided modifier into the metal melt.

The purpose of the invention is to reduce the consumption of a modifier by reducing its non-productive losses.

According to the method of modifying the cast iron, it is advantageous when casting the casting molds by means of automatic casting installations involving feeding the powder modifier with a gas-powder jet into a jet of liquid metal, the gas-powder jet is directed at an angle of 20-70 to the axis of the jet of liquid metal with a linear velocity of 3-15 m / s.

Example. Cast iron with carbon equivalent CE 3,70-3,75% (3,10-3,15% C; 1,90-1,95% Si; 0,65-0,70% Mp) and a temperature of 1400 ° C is poured in the form of technological wedge samples (metal capacity of 10 kg) through the filling chute, having a calibrated drain channel with a diameter of 16 mm with a mass velocity of 2.5 kg / s. Simultaneously and synchronously with the pouring of the liquid metal into the jet at a height of 10-20 mm from the point of entry into the mold funnel by means of a gas jet

& with

J

31640174

device (used for cleaning (with 1

ki castings with sand or shot are served with a powder modifier (ferrosilicon with barium with a grain size of 0.32-1.0 mm.

The effectiveness of the proposed and well-known methods of modifying the cast iron is judged by the average value of four white wedge samples of 100x50x20 mm in size, simultaneously poured into a mold with a metal plate, and the flow rate of the modifier.

The speed of the gas-powder jet is not measured (such an experience is with the help of high-speed filmmaking), but is determined by calculation using the empirical formula

V,

Where

to JSjFAiaia. SK TFc

С {- coefficient taking into account the loss of speed associated with the design parameters of the jet device, is equal to 0.5; compressed air consumption20

25

c in increasing the amount of chill from the wedge sample due to an increase in the modifier's unproductive losses due to the sliding impact of the jets, the failure of a certain amount of modifier particles to enter (the metal jet and falling into the pouring funnel on the metal mirror by oxidation and slagging. 1 The powder jet to the axis of the jet of liquid metal more than 70 ° (experiment 7) reduces the modifying effect, which is expressed in an increase in the amount of chipped off of the wedge sample due to an increase in unproductive modifier losses caused by harder impingement jets bounce a certain amount of modifier particles and their oxidation.

With a decrease in the linear velocity of the gas-powder jet of less than 3 m / s (test 8), the modifying effect decreases, which is expressed in an increase in the chill-off value of the wedge sample due to

 hedgehog.

ha, defined by 3 / s;

t - o

flow meter, m, the working nozzle cross-sectional area, m. The modifier consumption (mass modifier feed rate, g / s) is determined and determined by the corresponding

thirty

an increase in unproductive loss of the modifier, due to the non-introduction of a certain amount of particles into the jet of liquid metal due to their low kinetic energy, their oxidation, slagging and sublimation by heat flows.

The increase in the linear velocity of the gas-powder jet more

setting the dispenser, the feed powder- 35 m / s (experiment 9), although it provides

0

five

0

five

c in increasing the amount of chill from the wedge sample due to an increase in the modifier's unproductive loss due to the sliding impact of the jets, the failure to introduce a certain amount of modifier particles into the metal stream and falling into the pouring funnel on the metal mirror, oxidation and slagging. to the axis of the jet of liquid metal more than 70 ° (experiment 7), the modifying effect is lowered, resulting in an increase in the chill off value of the wedge sample due to an increase in non-productive losses of the modifier due to more severe collision of the jets, rebound of a certain amount of modifier particles and their oxidation.

With a decrease in the linear velocity of the gas-powder jet of less than 3 m / s (test 8), the modifying effect decreases, which is expressed in an increase in the chill-off value of the wedge sample due to

an increase in unproductive losses of the modifier due to the non-introduction of a certain amount of particles into the jet of liquid metal due to their low kinetic energy, their oxidation, slagging and sublimation by heat flows.

The increase in the linear velocity of the gas-powder jet more

 m / s (experience 9) although provides

a coherent modifier into the mixing chamber of the device, and can be varied within fairly wide limits depending on the mass flow rate of pouring the molten metal into the mold (kg / s) and the dose taken in technology (percentage of the mass of the molten metal).

As a carrier gas, dried compressed air is used.

The test results of the proposed and known methods for modifying pig iron under various processing conditions are shown in the table.

The best results of modifying the pig iron with the proposed method are achieved by supplying a gas-powder jet at an angle of 20-70 ° to the axis of the liquid metal with a linear velocity of 3-15 m / s (experiments 1-5).

When reducing the angle of the gas powder supply to the jet axis of the liquid metal less than 20 ° (experiment 6), the modifying effect, which expresses

-

0

five

0

five

Reducing the unproductive losses of the modifier is not rational and economically feasible, since it leads to an increase in the consumption of energy gas and a decrease in the quality of the castings due to the partial destruction of the liquid metal stream by increasing kinetic energy of the gas-powder jet, oxidation and a noticeable decrease in the melt temperature.

Thus, from the data in the table it follows that the proposed method of modifying pig iron as compared with the known method provides an increase in the modifying effect, expressed in reducing the chill off value of the wedge sample by 16.7–36.7% and reducing the consumption of modifier by 16.7–30 ,five%.

The proposed method for modifying cast iron can be used in the production of castings from chu516401

guna with lamellar and spherical graphite on lines with mechanized and automatic mold casting. In addition, it is advisable to use the proposed method for modifying cast iron when pouring casting molds using automatic casting plants based on induction furnaces.

Claims (1)

Claims method of modifying pig iron pre-. property when casting foundry ten one 74 forms by means of automatic casting installations, which include the supply of a powder-like modifier by a gas-powder jet to a jet of liquid metal, characterized in that, in order to reduce the flow rate of the modifier by reducing its non-productive losses, the gas-powder jet is directed at an angle of 20-70 to the axis of the jet of liquid metal linear speed of 3-15 m / s.