CN110396638A - A kind of inoculant of gray cast iron and preparation method thereof - Google Patents

Abstract

An inoculant for gray cast iron and a preparation method thereof, the chemical composition and mass percentage of the inoculant are: Si 20-30%, Mn 15-25%, Cr 10-20%, C<0.10%, Ca 1- 5%, Ba 1‑6%, N 1‑6%, P<0.05%, S<0.02%, and the rest is Fe. The preparation method of the inoculant of gray cast iron comprises the following steps: (1) mixing and crushing chromium alloy, calcium silicon and phosphide; (2) melting and cooling the obtained mixture; (3) cooling the obtained The final mixture is made into powder with manganese vanadium nitride; (4) paraffin wax is added to the obtained powder, and pressed into a block; (5) the block is sintered in a nitrogen-protected high-temperature furnace to obtain The sintered mixture; (6) Mixing and crushing the sintered mixture and the silicon-barium alloy by using a mechanical mixing method to obtain the gray cast iron inoculant. The inoculant prepared by adopting the invention can improve material properties and increase the strength of gray cast iron.

Description

A kind of inoculant of gray cast iron and preparation method thereof

technical field

The invention relates to the technical field of gray cast iron, in particular to an inoculant for gray cast iron and a preparation method thereof.

Background technique

Gray cast iron is low in price and high in quality, has no notch sensitivity, has good vibration damping performance, lubricating performance, casting performance and machinability, and is widely used in the foundry industry. With the development of modern industry, the requirements for the strength and reliability of castings are getting higher and higher. How to obtain more stable and reliable high-grade gray cast iron is the way of exploration for many foundry enterprises. Inoculation treatment is a very important process link in modern gray cast iron production. The purpose of inoculation treatment is to improve the eutectic solidification conditions, achieve whitening, improve processing performance; refine the eutectic group, promote the acquisition of A-type graphite, uniform distribution of graphite, improve matrix structure, improve mechanical properties, reduce section sensitivity, etc. .

The chemical composition and weight percentage of inoculants for gray cast iron are: Si 25%, Mn 10-20%, Cr 10-20%, C<0.10%, Ca 1-5%, Ba 1-6%, Cu 1- 6%, P<0.05%, S<0.02%, the rest is Fe, and the inoculant is silicon calcium barium inoculant. After the molten iron is smelted and qualified, inoculation treatment is carried out, and the furnace temperature is 1500°C. Inoculation in the ladle: respectively adding ferrosilicon inoculants with a mass percentage of 0.5%-0.75% for inoculation treatment, and then pouring the casting. A gray cast iron material with lower properties and higher alloy content is obtained. Adding alloying elements to gray cast iron will reduce the fluidity of molten iron and cause poor casting performance; at the same time, due to the addition of alloying elements, the hardness of gray cast iron will be increased, forming hard spots, and the cutting performance of gray cast iron will be poor.

Contents of the invention

The object of the present invention is to provide an inoculant for gray cast iron and a preparation method thereof. After inoculating the gray cast iron with the inoculant, the graphite will be shortened, the tail will be rounded, and the concentrated stress will be reduced; the degree of eutectic supercooling can be increased. , to refine the eutectic group; it can promote the nucleation of graphite, strengthen the pearlite matrix, improve the material properties, and significantly improve the strength and casting properties of gray cast iron.

The technical solution of the present invention is: an inoculant for improving the performance of gray cast iron, the chemical composition and mass percentage of the inoculant are: Si 20-30%, Mn 15-25%, Cr 10-20%, C<0.10 %, Ca 1-5%, Ba 1-6%, N1-6%, P<0.05%, S<0.02%, and the rest is Fe.

The preparation method of the inoculant of the gray cast iron comprises the following steps:

(1) After chromium alloy, silicon calcium, and phosphide are broken into 2-6mm particles, mix according to example 1500:2500:5;

(2) melting the mixture obtained in step (1) at 1500°C for 5 minutes, then cooling;

(3) The cooled mixture obtained in step (2) and manganese vanadium nitride are made into powder by atomization in a mass ratio of 2000:1000;

(4) Add paraffin to the powder obtained in step (3), and press it into a block under a pressure of 15-600Mpa;

(5) Carrying out multi-system sintering to the block made in step (4) in a nitrogen-protected high-temperature furnace to obtain a sintered mixture;

(6) Mix and crush the mixture sintered in step (5) and the silicon-barium alloy in a mass ratio of 1000:100 by mechanical mixing method to obtain a nitrogen-containing inoculant with 2-6 mm particles.

The added chemical elements are subject to the control of the chemical composition of the final inoculant.

Compared with prior art, the beneficial effect of the present invention is:

1. Adding nitrogen to gray cast iron can reduce the amount of precious metal elements added, while improving the mechanical properties and casting properties of the material;

2. Using manganese chromium vanadium nitride as the nitrogen addition agent of the inoculant can not only avoid the appearance of nitrogen pores, but also enhance the absorption effect of nitrogen;

3. Adding the inoculant of the present invention to cast iron can promote the shortening of graphite and the rounding of the tail, reducing concentrated stress; increasing the degree of eutectic supercooling and refining the eutectic cluster; promoting nucleation of graphite and strengthening the pearlite body , Improve the material performance; significantly improve the strength performance and casting performance of gray cast iron;

4. Nitrogen is relatively cheap and easy to obtain. Adding nitrogen can reduce or even replace alloying elements, which not only avoids the disadvantage of poor casting performance of adding alloying elements, but also reduces production costs and brings considerable economic benefits;

5. The tensile strength of castings inoculated with the inoculant can be increased by 45MPa to 85MPa after tensile testing.

Description of drawings

Fig. 1 is the casting metallographic diagram of the gray cast iron after inoculation treatment with the inoculant of the present invention.

Detailed ways

The technical solutions of the present invention will be further described below through specific examples.

Example 1

An inoculant for gray cast iron, the chemical composition and mass percentage of the inoculant are: Si 20%, Mn 25%, Cr 10%, C<0.1%, Ca 1-5%, Ba 1-6%, N 1 %, P<0.05%, S<0.02%, and the rest is Fe.

The preparation method of the inoculant of the gray cast iron comprises the following steps:

(1) After chromium alloy, calcium silicon, and phosphide are broken into 2-6mm particles, mix according to example 1000:2000:5;

(2) melting the mixture obtained in step (1) at 1500°C for 5 minutes, then cooling;

(3) The cooled mixture obtained in step (2) and manganese vanadium nitride are made into powder by atomization method in a mass ratio of 6000:5000;

(4) Add paraffin to the powder obtained in step (3), and press it into a block under a pressure of 15-600Mpa;

(5) Carrying out multi-system sintering to the block made in step (4) in a nitrogen-protected high-temperature furnace to obtain a sintered mixture;

(6) Mix and crush the mixture sintered in step (5) and the silicon-barium alloy in a mass ratio of 7500:600 by mechanical mixing method to obtain a nitrogen-containing inoculant with 2-6 mm particles.

Inspection method: Cut and number the tensile specimens on the casting, and make standard tensile specimens with d ₀ =10mm and L=5d ₀ according to GB/T 228.1-2010. Measure the tensile strength of 4 tensile samples on the WDW 3100 tensile testing machine, the tensile speed is 2mm/min, and the average tensile strength is taken as the detection result.

Test results: On the basis of HT200, the ferrosilicon inoculant was replaced by the inoculant prepared by the above method, and the strength of the casting was increased by 85MPa.

Example 2

An inoculant for gray cast iron, the chemical composition and mass percentage of the inoculant are: Si 25%, Mn 20%, Cr 15%, C<0.1%, Ca 1-5%, Ba 1-6%, N 3% , P<0.05%, S<0.02%, and the rest is Fe.

The preparation method of the inoculant of the gray cast iron comprises the following steps:

(1) After chromium alloy, silicon calcium, and phosphide are broken into 2-6mm particles, mix according to example 1500:2500:5;

(2) melting the mixture obtained in step (1) at 1500°C for 5 minutes, then cooling;

(3) The cooled mixture obtained in step (2) and manganese vanadium nitride are made into powder by atomization in a mass ratio of 2000:1000;

(4) Add paraffin to the powder obtained in step (3), and press it into a block under a pressure of 15-600Mpa;

(5) Carrying out multi-system sintering to the block made in step (4) in a nitrogen-protected high-temperature furnace to obtain a sintered mixture;

(6) Mix and crush the mixture sintered in step (5) and the silicon-barium alloy in a mass ratio of 1000:100 by mechanical mixing method to obtain a nitrogen-containing inoculant with 2-6 mm particles.

Inspection method: Cut and number the tensile specimens on the casting, and make standard tensile specimens with d ₀ =10mm and L=5d ₀ according to GB/T 228.1-2010. Measure the tensile strength of 4 tensile samples on the WDW 3100 tensile testing machine, the tensile speed is 2mm/min, and the average tensile strength is taken as the detection result.

Test results: On the basis of HT250, the inoculant prepared by the above method was used to replace the ferrosilicon inoculant, and the strength of the casting was increased by 45MPa.

Example 3

An inoculant for gray cast iron, the chemical composition and mass percentage of the inoculant are: Si 30%, Mn 15%, Cr 20%, C<0.1%, Ca 1-5%, Ba 1-6%, N 6% , P<0.05%, S<0.02%, and the rest is Fe.

The preparation method of the inoculant of the gray cast iron comprises the following steps:

(1) After the chromium alloy, calcium silicon and phosphide are broken into 2-6mm particles, they are mixed according to the mass ratio of 2000:3000:5;

(2) melting the mixture obtained in step (1) at 1500°C for 5 minutes, then cooling;

(3) The cooled mixture obtained in step (2) and manganese vanadium nitride are made into powder by atomization in a mass ratio of 1000:300;

(4) Add paraffin to the powder obtained in step (3), and press it into a block under a pressure of 15-600Mpa;

(5) Carrying out multi-system sintering to the block made in step (4) in a nitrogen-protected high-temperature furnace to obtain a sintered mixture;

(6) Mix and crush the mixture sintered in step (5) and the silicon-barium alloy in a mass ratio of 6500:600 by mechanical mixing method to obtain a nitrogen-containing inoculant with 2-6 mm particles.

Inspection method: Cut and number the tensile specimens on the casting, and make standard tensile specimens with d ₀ =10mm and L=5d ₀ according to GB/T 228.1-2010. Measure the tensile strength of 4 tensile samples on the WDW 3100 tensile testing machine, the tensile speed is 2mm/min, and the average tensile strength is taken as the detection result.

Test results: On the basis of HT300, the ferrosilicon inoculant was replaced by the inoculant prepared by the above method, and the strength of the casting was increased by 60MPa.

Table 1 is a comparative table of tensile strength of castings treated with ferrosilicon inoculants and inoculants of the present invention.

Claims (5)

1. a kind of inovulant of gray cast iron, which is characterized in that the chemical component and its mass percent of the inovulant are as follows: Si 20- 30%, Mn 15-25%, Cr 10-20%, C < 0.10%, Ca 1-5%, Ba 1-6%, N 1-6%, P < 0.05%, S < 0.02%, remaining is Fe.

2. the preparation method of the inovulant of gray cast iron according to claim 1, which comprises the steps of:

(1) it after evanohm, silico-calcium, phosphide being broken into 2-6mm particle, is carried out by example 1000~2000: 2000~3000: 5 Mixing；

(2) obtained mixture is carried out melting 5 minutes under the conditions of 1500 DEG C, is cooled down immediately；

(3) powder is made using atomization in obtained mixture after cooling and manganese vanadium nitride example 2: 1 in mass ratio；

(4) paraffin will be added in obtained powder, under 15-600Mpa pressure, is pressed into block；

(5) manufactured block is subjected to heterogeneous sintering in the high temperature furnace of nitrogen protection, obtains sintered mixture；

(6) sintered mixture mix with Si-Ba alloy example 10: 1 in mass ratio using mechanical mixing and be crushed, obtained To the gray cast iron inovulant of 2-6mm particle.

3. the preparation method of the inovulant of gray cast iron according to claim 1, which is characterized in that the inovulant chemistry at Point and its mass percent are as follows: Si 20%, Mn 25%, Cr 10%, C < 0.1%, Ca 1-5%, Ba 1-6%, N 1%, P < 0.05%, S < 0.02%, remaining is Fe,

The preparation method of the inovulant of the gray cast iron, includes the following steps:

(1) it after evanohm, silico-calcium, phosphide being broken into 2-6mm particle, is mixed by example 1000: 2000: 5；

(2) mixture obtained in step (1) is carried out melting 5 minutes under the conditions of 1500 DEG C, is cooled down immediately；

(3) mixture after cooling obtained in step (2) and manganese vanadium nitride example 6000: 5000 in mass ratio are used into atomization Powder is made in method；

(4) paraffin is added in the powder obtained in step (3), under 15-600Mpa pressure, is pressed into block；

(5) block manufactured in step (4) is subjected to heterogeneous sintering in the high temperature furnace of nitrogen protection, obtained sintered Mixture；

(6) using mechanical mixing by sintered mixture in step (5) and Si-Ba alloy example 7500: 600 in mass ratio into Row mixing is broken, obtains the nitrogenous inovulant of 2-6mm particle.

4. the inovulant of gray cast iron described in claim 1-3 any one, which is characterized in that the chemical component of the inovulant and Its mass percent are as follows: Si 25%, Mn 20%, Cr 15%, C < 0.1%, Ca 1-5%, Ba 1-6%, N 3%, P < 0.05%, S < 0.02%, remaining is Fe.

5. the inovulant of gray cast iron described in claim 1-3 any one, which is characterized in that the chemical component of the inovulant and Its mass percent are as follows: Si 30%, Mn 15%, Cr 20%, C < 0.1%, Ca 1-5%, Ba 1-6%, N 6%, P < 0.05%, S < 0.02%, remaining is Fe.