CN112589059A

CN112589059A - Casting method for adding trace silicon carbide into pouring ladle

Info

Publication number: CN112589059A
Application number: CN202011347498.0A
Authority: CN
Inventors: 王忠全; 单学义; 王树兴; 侯贺涛; 赵书俊
Original assignee: Laizhou Hongyuan Bench Vice Manufacture Co ltd
Current assignee: Laizhou Hongyuan Bench Vice Manufacture Co ltd
Priority date: 2020-11-26
Filing date: 2020-11-26
Publication date: 2021-04-02

Abstract

The invention discloses a casting method for adding trace silicon carbide into a pouring ladle, which comprises the following steps: melting an iron source at 1530-1550 ℃, adding silicon carbide, a nodulizer and an inoculant into a pouring ladle for smelting, and casting at 1420-1450 ℃ after the molten iron reaches the standard. The invention has the beneficial effects that: the casting method for adding trace silicon carbide into the pouring ladle can realize the effect of adding silicon carbide by using a small amount of silicon carbide, has the effect of deoxidation, and can also obviously improve the nodulizing rate, thereby reducing the addition amount of a nodulizer, improving the nodulizing rate from 80 percent to more than 90 percent at least, and improving the tensile strength of a casting by 20 to 30 percent; according to the invention, the silicon carbide is added into the pouring ladle, so that the flow stability of the molten iron can be improved, the occurrence of segregation phenomenon is inhibited, and the cutting performance of the casting is improved.

Description

Casting method for adding trace silicon carbide into pouring ladle

Technical Field

The invention relates to metal casting, in particular to a casting method for adding trace silicon carbide into a pouring ladle.

Background

The melting point of the silicon carbide is 2700 ℃, and the dissolution temperature is about 1200 ℃. The research shows that: the silicon carbide has the effects of deoxidizing, increasing silicon, reducing the super-cooling degree of the inoculated molten iron, purifying the molten iron, increasing graphite cores and improving the graphite form, thereby improving the nodularity of the nodular cast iron and the mechanical property of the casting, and having good effect on improving the casting quality of the cast iron. The existing casting production process flow is generally that silicon carbide is added into an electric furnace in the smelting process, namely when molten iron is in a molten state, more silicon carbide needs to be added in the molten state to meet the requirement, and the adding amount is generally 1% -1.2% of the total molten iron amount.

Disclosure of Invention

The invention provides a casting method for adding trace silicon carbide into a pouring ladle aiming at the problem of excessive silicon carbide added in the existing molten iron smelting process, which comprises the steps of melting an iron source at 1530-1550 ℃, adding silicon carbide, a nodulizer and an inoculant into the pouring ladle for smelting, and casting at 1420-1450 ℃ after the molten iron reaches the standard.

Further, the iron source comprises 20-30% of ordinary Q10 or Q12 raw material iron, 35-40% of pure scrap steel and 40% of scrap returns according to the following molten iron components: 3.6%, Si: 1.5-1.9%, Mn: 0.25%, S: 0.01-0.16%, P: 0.027-0.035% and Cr: compounding under the condition of less than 0.05 percent.

Further, the grain size of the silicon carbide is 3-5mm, the dosage of the silicon carbide is 0.2-0.3% of the weight of the molten iron, the addition amount of the nodulizer is 1.1-1.3% of the weight of the molten iron, and the addition amount of the inoculant is 0.2-0.5% of the weight of the molten iron.

Further, the standard that the molten iron reaches before casting is as follows: c: 3.7-3.8%; si: 2.2-2.8%; mn: 0.25 percent and; s: 0.01-0.16%, P: 0.027-0.035%, Cr: < 0.05%, Ti: < 0.03%, Mg: 0.027-0.05%, rare earth Re: 0.01-0.025% and 4.3-4.6% carbon equivalent.

The invention has the beneficial effects that: the casting method for adding trace silicon carbide into the pouring ladle can realize the effect of adding silicon carbide by using a small amount of silicon carbide, has the effect of deoxidation, and can also obviously improve the nodulizing rate, thereby reducing the addition amount of a nodulizer, improving the nodulizing rate from 80 percent to more than 90 percent at least, and improving the tensile strength of a casting by 20 to 30 percent; according to the invention, the silicon carbide is added into the pouring ladle, so that the flow stability of the molten iron can be improved, the occurrence of segregation phenomenon is inhibited, and the cutting performance of the casting is improved.

Detailed Description

The present invention is described below with reference to examples, which are provided for illustration only and are not intended to limit the scope of the present invention.

Example 1

A casting method for adding trace silicon carbide into a pouring ladle comprises the following steps:

1) the method adopts 30 percent of common Q10 raw material iron, 40 percent of pure scrap steel and 40 percent of scrap returns as smelting iron sources, and the components of the molten iron in front of the furnace meet the following requirements by proportion: c: 3.6%, Si: 1.5-1.9%, Mn: 0.25%, S: 0.01-0.16%, P: 0.027-0.035% and Cr: less than 0.05 percent;

2) melting the proportioned iron source at 1530 ℃, adding silicon carbide with the grain diameter of 3mm into a pouring ladle, wherein the dosage of the silicon carbide is 0.2 percent of the weight of the molten iron, adding a nodulizer accounting for 1.3 percent of the weight of the molten iron and an inoculant accounting for 0.5 percent of the weight of the molten iron, and controlling the components of the molten iron during pouring to be as follows: c: 3.7-3.8%; si: 2.2-2.8%; mn: 0.25 percent and; s: 0.01-0.16%, P: 0.027-0.035%, Cr: < 0.05%, Ti: < 0.03%, Mg: 0.027-0.05%, rare earth Re: 0.01-0.025%, carbon equivalent is 4.3-4.6;

3) casting at 1450 deg.C.

Example 2

1) the method adopts 20 percent of common Q12 raw material iron, 35 percent of pure scrap steel and 40 percent of scrap returns as smelting iron sources, and the components of the molten iron in front of the furnace meet the following requirements by proportion: c: 3.6%, Si: 1.5-1.9%, Mn: 0.25%, S: 0.01-0.16%, P: 0.027-0.035% and Cr: less than 0.05 percent;

2) melting proportioned iron source at 1550 ℃, adding silicon carbide with the particle size of 5mm into a pouring ladle, wherein the dosage of the silicon carbide is 0.3 percent of the weight of molten iron, and then adding a nodulizer accounting for 1.1 percent of the weight of the molten iron and an inoculant accounting for 0.2 percent of the weight of the molten iron, and controlling the components of the molten iron during pouring to be as follows: c: 3.7-3.8%; si: 2.2-2.8%; mn: 0.25 percent and; s: 0.01-0.16%, P: 0.027-0.035%, Cr: < 0.05%, Ti: < 0.03%, Mg: 0.027-0.05%, rare earth Re: 0.01-0.025%, carbon equivalent is 4.3-4.6;

3) casting at 1420 ℃.

Comparative example 1 silicon carbide was added in an amount of 1% by weight of molten iron after melting and melting in example 1, and the others were unchanged.

The cast articles of examples 1 and 2 and comparative example 1 were subjected to the following tests as shown in table 1.

TABLE 1 test of the properties of the castings of examples, 2 and comparative examples

	Example 1	Example 2	Comparative example 1
				Tensile Strength σ b (MPa)	480	467	491
Yield strength sigma 0.2(MPa)	325	316	332
				Elongation delta (%)	10.4	11.2	9.7
Hardness (HB)	210	192	203

As can be seen from the data in Table 1, the casting method of the present invention in which a trace amount of silicon carbide is added to the ladle does not cause a decrease in the properties of the resulting casting, as compared with the prior art.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A casting method for adding trace silicon carbide into a pouring ladle is characterized by comprising the following steps: melting an iron source at 1530-1550 ℃, adding silicon carbide, a nodulizer and an inoculant into a pouring ladle for smelting, and casting at 1420-1450 ℃ after the molten iron reaches the standard.

2. The method of claim 1, wherein the iron source is 20-30% of ordinary Q10 or Q12 raw iron, 35-40% of pure scrap steel and 40% of scrap returns, and the molten iron content satisfies C: 3.6%, Si: 1.5-1.9%, Mn: 0.25%, S: 0.01-0.16%, P: 0.027-0.035% and Cr: compounding under the condition of less than 0.05 percent.

3. The method according to claim 1, wherein the silicon carbide has a particle size of 3-5mm and is added in an amount of 0.2-0.3 wt% based on the molten iron, the nodulizer is added in an amount of 1.1-1.3 wt% based on the molten iron, and the inoculant is added in an amount of 0.2-0.5 wt% based on the molten iron.

4. The method of claim 1, wherein the standard met by the molten iron prior to casting is: c: 3.7-3.8%; si: 2.2-2.8%; mn: 0.25 percent and; s: 0.01-0.16%, P: 0.027-0.035%, Cr: < 0.05%, Ti: < 0.03%, Mg: 0.027-0.05%, rare earth Re: 0.01-0.025% and 4.3-4.6% carbon equivalent.