Corrosion-resistant high-pressure-resistant thin-wall pump shell and production method thereof

Abstract

The application relates to the technical field of pump shell production, and discloses a corrosion-resistant and high-pressure-resistant thin-wall pump shell and a production method thereof, which are composed of the following element components and weight percentages: C: 3.5-3.8%, Si: 2.5-2.8%, Cr: 22-26%, Mn: 0.3-0.5%, S: <=0.35%, P: <=0.05%, Mg: 0.03-0.05%, Re: 0.02-0.03%, and the balance of Fe and inevitable impurities. The pump shell produced by the element component proportioning and the preparation process has the following actual physical and chemical properties: tensile strength >=470 Rm / MPa, elongation rate >=20 A / %, and corrosion efficiency <=0.02 mm / a, the physical and chemical properties are excellent, the cost of customers is reduced, the product weight is reduced, the pump body wall thickness is reduced, the tensile strength required for pressure test is greatly higher than that of the ordinary national standard, the pump shell is suitable for pumping work in various environments, and especially for ocean-going ships, the pump shell can be assembled and used with excellent thin-wall characteristics and corrosion-resistant high-pressure performance.

Description

Technical Field

[0001] This invention relates to the field of pump casing manufacturing technology, specifically to a corrosion-resistant and high-pressure-resistant thin-walled pump casing and its manufacturing method. Background Technology

[0002] A pump is a machine that transports or pressurizes fluids. It transfers the mechanical energy of a prime mover or other external energy to a liquid, increasing the liquid's energy. Pumps are mainly used to transport liquids such as water, oil, acid and alkali solutions, emulsions, suspensions, and liquid metals. They can also transport liquid-gas mixtures and liquids containing suspended solids. They are widely used in all areas of life. Whether it is airplanes, rockets, tanks, submarines, drilling, mining, trains, ships, or daily life, pumps are needed everywhere and are running everywhere. They are a major product in the machinery industry.

[0003] Pumps are primarily made of stainless steel (SS 316 or SS 304) or cast iron. For pumps used in marine applications, due to the corrosive nature of seawater, 316 stainless steel is typically used. As shown in existing patent technology: a formula for a super bidirectional stainless steel pump casing (publication number CN109554614A) is disclosed on the China Patent Network. The formula proportions by mass percentage are as follows: C: ≦0.03%, Si: 0.60-0.90%, Mn: 0.50-0.80%, P: ≦ With the following composition: 0.03%, S: ≦0.025%, Cr: 25.2-25.7%, Ni: 6.7-7.2%, Mo: 3.4-3.7%, Cu: 0.6-0.8%, W: 0.7-0.9%, N: 0.20-0.24%, this invention, through its formulation targeting precision castings of marine pump casings, overcomes the technical challenge of existing non-vacuum medium-frequency induction furnaces being unable to properly produce super duplex stainless steel precision castings, and is able to produce precision castings of marine pump casings with excellent mechanical properties.

[0004] However, the existing pump casings do not have a precise carbon-silicon ratio, which significantly affects the metallographic structure and physical properties of the casing, resulting in certain defects. Therefore, those skilled in the art provide a corrosion-resistant, high-pressure-resistant thin-walled pump casing and its manufacturing method to solve the problems mentioned in the background. Summary of the Invention

[0005] The purpose of this invention is to provide a corrosion-resistant and high-pressure-resistant thin-walled pump casing and its manufacturing method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a corrosion-resistant and high-pressure-resistant thin-walled pump casing, comprising the following elemental composition and weight percentages: C: 3.5-3.8%, Si: 2.5-2.8%, Cr: 22-26%, Mn: 0.3-0.5%, S: ≤0.35%, P: ≤0.05%, Mg: 0.03-0.05%, Re: 0.02-0.03%, with the balance being Fe and unavoidable impurities;

[0007] As a further embodiment of the present invention, the elemental composition and weight percentage of the thin-walled pump casing are as follows: C: 3.5%, Si: 2.5%, Cr: 22%, Mn: 0.3%, S: 0.35%, P: 0.05%, Mg: 0.03%, Re: 0.02%, with the balance being Fe and unavoidable impurities.

[0008] As a further embodiment of the present invention, the elemental composition and weight percentage of the thin-walled pump casing are as follows: C: 3.6%, Si: 2.6%, Cr: 23%, Mn: 0.35%, S: 0.30%, P: 0.04%, Mg: 0.035%, Re: 0.022%, with the balance being Fe and unavoidable impurities.

[0009] As a further embodiment of the present invention, the elemental composition and weight percentage of the thin-walled pump casing are as follows: C: 3.7%, Si: 2.7%, Cr: 24%, Mn: 0.4%, S: 0.25%, P: 0.03%, Mg: 0.04%, Re: 0.026%, with the balance being Fe and unavoidable impurities.

[0010] As a further embodiment of the present invention, the elemental composition and weight percentage of the thin-walled pump casing are as follows: C: 3.8%, Si: 2.8%, Cr: 26%, Mn: 0.5%, S: 0.02%, P: 0.02%, Mg: 0.05%, Re: 0.03%, with the balance being Fe and unavoidable impurities.

[0011] A method for producing a corrosion-resistant and high-pressure-resistant thin-walled pump casing includes the following steps:

[0012] Step 1: Furnace charge selection. Select pump casing raw materials according to quantitative proportions. First, use high-purity pig iron, scrap steel, and recycled materials as the furnace charge base. According to their smelting difficulty, the recycled materials, high-purity pig iron, and scrap steel are laid on the furnace bottom in order. The charging method is tight at the bottom and loose at the top. Then, other raw materials are loaded into the furnace in sequence.

[0013] Step 2: Smelting of furnace charge. A medium-frequency induction furnace is selected, and smelting is carried out at 1450℃-1550℃ to obtain molten iron.

[0014] Step 3: Wire feeding and spheroidization. After molten iron is poured into a transfer ladle and left to stand for 1-2 minutes, a slag removal process is performed. Then, it is transferred to the bottom of the wire feeder. A steel strip is used to wrap the ferrosilicon rare earth magnesium spheroidizing agent in the cored wire. The amount of ferrosilicon rare earth magnesium spheroidizing agent added is 0.6-0.1% of the total weight of the molten iron. Then, the wire feeder feeds it into the bottom of the transfer ladle to achieve the purpose of spheroidization.

[0015] Step 4: Casting and molding. The strengthened molten iron is poured into a pre-made mold and heated in a stepwise uniform manner at 100℃ / min to between 850℃ and 900℃. The temperature is held for 1-2 hours. Then, the temperature is heated again in a stepwise uniform manner at 100℃ / min to between 1050℃ and 1100℃. The temperature is held for 2-3 hours. The pump casing is then removed and quickly immersed in cooling oil for 20-30 minutes to complete the heating and quenching of the inner shell of the mold. After that, it is removed and cooled to improve its metallographic properties.

[0016] As a further embodiment of the present invention: the tapping temperature of the molten iron in step two is maintained at 1500℃-1550℃, the temperature of the molten iron in the transfer ladle in step three is maintained at 1450℃-1500℃, and the casting temperature in step four is maintained at 1350℃-1400℃.

[0017] As a further aspect of the present invention: in step four, when smelting and pouring molten iron, a special pouring cup is prepared in advance, bottom pouring is implemented, a special ceramic pipe pouring channel is installed, and a special filter screen is installed to ensure that the molten iron rises evenly during pouring.

[0018] As a further aspect of the present invention: in step four, when the mold is made, a special core is used, and the clay core is assembled and then the core is laid as a whole to ensure that the clay core is flawless. In addition, the appearance is carefully controlled in terms of shaping, flow coating, brushing, cleaning flow marks, and baking details to ensure the appearance of the product.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The pump casing produced by the elemental composition and preparation process of this invention, after adjusting the carbon-silicon equivalent of the material, feeding spheroidization, and casting inoculation, exhibits excellent physical and chemical properties, including tensile strength ≥470Rm / MPa, elongation ≥20A / %, and corrosion efficiency ≤0.02mm / a. It features high hardness, good toughness, and corrosion resistance, enabling customers to reduce costs, product weight, and pump body wall thickness. The required tensile strength under pressure testing is significantly higher than ordinary national standards, making it better suited for pumping operations in various environments. Especially for ocean-going vessels, it can be assembled and used with excellent thin-wall characteristics, corrosion resistance, and high-pressure performance. Detailed Implementation

[0021] In an embodiment of the present invention, a corrosion-resistant and high-pressure-resistant thin-walled pump casing is composed of the following elements and weight percentages: C: 3.5%, Si: 2.5%, Cr: 22%, Mn: 0.3%, S: 0.35%, P: 0.05%, Mg: 0.03%, Re: 0.02%, with the balance being Fe and unavoidable impurities.

[0022] The manufacturing method of corrosion-resistant and high-pressure-resistant thin-walled pump casing includes the following steps:

[0023] Step 1: Furnace charge selection. Select pump casing raw materials according to quantitative proportions. First, use high-purity pig iron, scrap steel, and recycled materials as the furnace charge base. According to their smelting difficulty, the recycled materials, high-purity pig iron, and scrap steel are laid on the furnace bottom in order. The charging method is tight at the bottom and loose at the top. Then, other raw materials are loaded into the furnace in sequence.

[0024] Step 2: Smelting of furnace charge. A medium-frequency induction furnace is selected, and smelting is carried out at 1450℃-1550℃ to obtain molten iron.

[0025] Step 3: Wire feeding and spheroidization. After molten iron is poured into a transfer ladle and left to stand for 1-2 minutes, a slag removal process is performed. Then, it is transferred to the bottom of the wire feeder. A steel strip is used to wrap the ferrosilicon rare earth magnesium spheroidizing agent in the cored wire. The amount of ferrosilicon rare earth magnesium spheroidizing agent added is 0.6-0.1% of the total weight of the molten iron. Then, the wire feeder feeds it into the bottom of the transfer ladle to achieve the purpose of spheroidization.

[0026] Step 4: Pour the strengthened molten iron into a pre-made mold, and heat it uniformly in steps at 100℃ / min to between 850℃ and 900℃, hold it at that temperature for 1-2 hours, and then heat it uniformly in steps at 100℃ / min to between 1050℃ and 1100℃, hold it at that temperature for 2-3 hours, remove the pump casing, and quickly immerse it in cooling oil for 20-30 minutes to complete the heating and quenching of the inner shell of the mold. Then remove it and cool it to improve its metallographic properties.

[0027] In step two, the tapping temperature of the molten iron is maintained at 1500℃-1550℃; in step three, the temperature of the molten iron in the transfer ladle is maintained at 1450℃-1500℃; and in step four, the pouring temperature is maintained at 1350℃.

[0028] -1400℃.

[0029] In step four, when pouring molten iron, a special pouring cup is prepared in advance, bottom pouring is implemented, a special ceramic tube pouring channel is installed, and a special filter screen is installed to ensure that the molten iron rises evenly during pouring.

[0030] In step four, when making the mold, a special core is used. After the clay core is assembled, the core is placed as a whole to ensure that the clay core is flawless. The appearance is also carefully controlled in terms of shaping, flow coating, brushing, cleaning flow marks, and baking to ensure the product's appearance.

[0031] Example 2:

[0032] In this embodiment of the invention, a corrosion-resistant and high-pressure-resistant thin-walled pump casing is composed of the following elements and weight percentages: C: 3.6%, Si: 2.6%, Cr: 23%, Mn: 0.35%, S: 0.30%, P: 0.04%, Mg: 0.035%, Re: 0.022%, with the balance being Fe and unavoidable impurities.

[0033] The manufacturing method of corrosion-resistant and high-pressure-resistant thin-walled pump casing includes the following steps:

[0034] Step 1: Furnace charge selection. Select pump casing raw materials according to quantitative proportions. First, use high-purity pig iron, scrap steel, and recycled materials as the furnace charge base. According to their smelting difficulty, the recycled materials, high-purity pig iron, and scrap steel are laid on the furnace bottom in order. The charging method is tight at the bottom and loose at the top. Then, other raw materials are loaded into the furnace in sequence.

[0035] Step 2: Smelting of furnace charge. A medium-frequency induction furnace is selected, and smelting is carried out at 1450℃-1550℃ to obtain molten iron.

[0036] Step 3: Wire feeding and spheroidization. After molten iron is poured into a transfer ladle and left to stand for 1-2 minutes, a slag removal process is performed. Then, it is transferred to the bottom of the wire feeder. A steel strip is used to wrap the ferrosilicon rare earth magnesium spheroidizing agent in the cored wire. The amount of ferrosilicon rare earth magnesium spheroidizing agent added is 0.6-0.1% of the total weight of the molten iron. Then, the wire feeder feeds it into the bottom of the transfer ladle to achieve the purpose of spheroidization.

[0037] Step 4: Pour the strengthened molten iron into a pre-made mold, and heat it uniformly in steps at 100℃ / min to between 850℃ and 900℃, hold it at that temperature for 1-2 hours, and then heat it uniformly in steps at 100℃ / min to between 1050℃ and 1100℃, hold it at that temperature for 2-3 hours, remove the pump casing, and quickly immerse it in cooling oil for 20-30 minutes to complete the heating and quenching of the inner shell of the mold. Then remove it and cool it to improve its metallographic properties.

[0038] Example 3:

[0039] In an embodiment of the present invention, a corrosion-resistant and high-pressure-resistant thin-walled pump casing is composed of the following elements and weight percentages: C: 3.7%, Si: 2.7%, Cr: 24%, Mn: 0.4%, S: 0.25%, P: 0.03%, Mg: 0.04%, Re: 0.026%, with the balance being Fe and unavoidable impurities.

[0040] The manufacturing method of corrosion-resistant and high-pressure-resistant thin-walled pump casing includes the following steps:

[0041] Step 1: Furnace charge selection. Select pump casing raw materials according to quantitative proportions. First, use high-purity pig iron, scrap steel, and recycled materials as the furnace charge base. According to their smelting difficulty, the recycled materials, high-purity pig iron, and scrap steel are laid on the furnace bottom in order. The charging method is tight at the bottom and loose at the top. Then, other raw materials are loaded into the furnace in sequence.

[0042] Step 2: Smelting of furnace charge. A medium-frequency induction furnace is selected, and smelting is carried out at 1450℃-1550℃ to obtain molten iron.

[0043] Step 3: Wire feeding and spheroidization. After molten iron is poured into a transfer ladle and left to stand for 1-2 minutes, a slag removal process is performed. Then, it is transferred to the bottom of the wire feeder. A steel strip is used to wrap the ferrosilicon rare earth magnesium spheroidizing agent in the cored wire. The amount of ferrosilicon rare earth magnesium spheroidizing agent added is 0.6-0.1% of the total weight of the molten iron. Then, the wire feeder feeds it into the bottom of the transfer ladle to achieve the purpose of spheroidization.

[0044] Step 4: Pour the strengthened molten iron into a pre-made mold, and heat it uniformly in steps at 100℃ / min to between 850℃ and 900℃, hold it at that temperature for 1-2 hours, and then heat it uniformly in steps at 100℃ / min to between 1050℃ and 1100℃, hold it at that temperature for 2-3 hours, remove the pump casing, and quickly immerse it in cooling oil for 20-30 minutes to complete the heating and quenching of the inner shell of the mold. Then remove it and cool it to improve its metallographic properties.

[0045] Example 4:

[0046] In this embodiment of the invention, a corrosion-resistant and high-pressure-resistant thin-walled pump casing is composed of the following elemental composition and weight percentages: C: 3.8%, Si: 2.8%, Cr: 26%, Mn: 0.5%, S: 0.02%, P: 0.02%, Mg: 0.05%, Re: 0.03%, with the balance being Fe and unavoidable impurities.

[0047] The manufacturing method of corrosion-resistant and high-pressure-resistant thin-walled pump casing includes the following steps:

[0048] Step 1: Furnace charge selection. Select pump casing raw materials according to quantitative proportions. First, use high-purity pig iron, scrap steel, and recycled materials as the furnace charge base. According to their smelting difficulty, the recycled materials, high-purity pig iron, and scrap steel are laid on the furnace bottom in order. The charging method is tight at the bottom and loose at the top. Then, other raw materials are loaded into the furnace in sequence.

[0049] Step 2: Smelting of furnace charge. A medium-frequency induction furnace is selected, and smelting is carried out at 1450℃-1550℃ to obtain molten iron.

[0050] Step 3: Wire feeding and spheroidization. After molten iron is poured into a transfer ladle and left to stand for 1-2 minutes, a slag removal process is performed. Then, it is transferred to the bottom of the wire feeder. A steel strip is used to wrap the ferrosilicon rare earth magnesium spheroidizing agent in the cored wire. The amount of ferrosilicon rare earth magnesium spheroidizing agent added is 0.6-0.1% of the total weight of the molten iron. Then, the wire feeder feeds it into the bottom of the transfer ladle to achieve the purpose of spheroidization.

[0051] Step 4: Pour the strengthened molten iron into a pre-made mold, and heat it uniformly in steps at 100℃ / min to between 850℃ and 900℃, hold it at that temperature for 1-2 hours, and then heat it uniformly in steps at 100℃ / min to between 1050℃ and 1100℃, hold it at that temperature for 2-3 hours, remove the pump casing, and quickly immerse it in cooling oil for 20-30 minutes to complete the heating and quenching of the inner shell of the mold. Then remove it and cool it to improve its metallographic properties.

[0052] The pump casings prepared based on the above embodiments 1-4 have the following mechanical properties:

[0053] Table 1:

[0054]

[0055] The pump casings prepared through the above four sets of embodiments have the characteristics of high hardness, good toughness, and corrosion resistance. In particular, after adjusting the carbon-silicon equivalent of the material, feeding spheroidization, and casting inoculation process, its tensile strength is ≥470Rm / MPa, elongation is ≥20A / %, and corrosion efficiency is ≤0.02mm / a. Its various physical and chemical properties are excellent, and it can be better suited for pumping work in various environments. Especially for ocean-going vessels, it can be assembled and used with excellent thin-wall characteristics, corrosion resistance, and high pressure performance.

[0056] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A corrosion-resistant and high-pressure-resistant thin-walled pump casing, characterized in that, The elemental composition and weight percentages are as follows: C: 3.5-3.8%, Si: 2.5-2.8%, Cr: 22-26%, Mn: 0.3-0.5%, S: ≤0.35%, P: ≤0.05%, Mg: 0.03-0.05%, RE: 0.02-0.03%, balance being Fe and unavoidable impurities; The method for producing this high-pressure thin-walled pump casing includes the following steps: Step 1: Furnace charge selection. Select pump casing raw materials according to quantitative proportions. First, use high-purity pig iron, scrap steel, and recycled materials as the furnace charge base. According to their smelting difficulty, the recycled materials, high-purity pig iron, and scrap steel are laid on the furnace bottom in order. The charging method is tight at the bottom and loose at the top. Then, other raw materials are loaded into the furnace in sequence. Step 2: Smelting of furnace charge. A medium-frequency induction furnace is selected, and smelting is carried out at 1450℃-1550℃ to obtain molten iron. Step 3: Wire feeding and spheroidization. After molten iron is poured into a transfer ladle and left to stand for 1-2 minutes, a slag removal process is performed. Then, it is transferred to the bottom of the wire feeder. A steel strip is used to wrap the ferrosilicon rare earth magnesium spheroidizing agent in the cored wire. The amount of ferrosilicon rare earth magnesium spheroidizing agent added is 0.6-0.1% of the total weight of the molten iron. Then, the wire feeder feeds it into the bottom of the transfer ladle to achieve the purpose of spheroidization. Step 4: Casting and molding. The strengthened molten iron is poured into a pre-made mold and heated in a stepwise uniform manner at 100℃ / min to between 850℃ and 900℃. The temperature is held for 1-2 hours. Then, the temperature is heated again in a stepwise uniform manner at 100℃ / min to between 1050℃ and 1100℃. The temperature is held for 2-3 hours. The pump casing is then removed and quickly immersed in cooling oil for 20-30 minutes to complete the heating and quenching of the inner shell of the mold. After that, it is removed and cooled to improve its metallographic properties.

2. The corrosion-resistant and high-pressure-resistant thin-walled pump casing according to claim 1, characterized in that, The elemental composition and weight percentage of the thin-walled pump casing are as follows: C: 3.5%, Si: 2.5%, Cr: 22%, Mn: 0.3%, S: 0.35%, P: 0.05%, Mg: 0.03%, RE: 0.02%, with the balance being Fe and unavoidable impurities.

3. The corrosion-resistant and high-pressure-resistant thin-walled pump casing according to claim 1, characterized in that, The elemental composition and weight percentage of the thin-walled pump casing are as follows: C: 3.6%, Si: 2.6%, Cr: 23%, Mn: 0.35%, S: 0.30%, P: 0.04%, Mg: 0.035%, RE: 0.022%, with the balance being Fe and unavoidable impurities.

4. The corrosion-resistant and high-pressure-resistant thin-walled pump casing according to claim 1, characterized in that, The elemental composition and weight percentage of the thin-walled pump casing are as follows: C: 3.7%, Si: 2.7%, Cr: 24%, Mn: 0.4%, S: 0.25%, P: 0.03%, Mg: 0.04%, RE: 0.026%, with the balance being Fe and unavoidable impurities.

5. The corrosion-resistant and high-pressure-resistant thin-walled pump casing according to claim 1, characterized in that, The elemental composition and weight percentage of the thin-walled pump casing are as follows: C: 3.8%, Si: 2.8%, Cr: 26%, Mn: 0.5%, S: 0.02%, P: 0.02%, Mg: 0.05%, RE: 0.03%, with the balance being Fe and unavoidable impurities.

6. A method for producing a corrosion-resistant and high-pressure-resistant thin-walled pump casing according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Furnace charge selection. Select pump casing raw materials according to quantitative proportions. First, use high-purity pig iron, scrap steel, and recycled materials as the furnace charge base. According to their smelting difficulty, the recycled materials, high-purity pig iron, and scrap steel are laid on the furnace bottom in order. The charging method is tight at the bottom and loose at the top. Then, other raw materials are loaded into the furnace in sequence. Step 2: Smelting of furnace charge. A medium-frequency induction furnace is selected, and smelting is carried out at 1450℃-1550℃ to obtain molten iron. Step 3: Wire feeding and spheroidization. After molten iron is poured into a transfer ladle and left to stand for 1-2 minutes, a slag removal process is performed. Then, it is transferred to the bottom of the wire feeder. A steel strip is used to wrap the ferrosilicon rare earth magnesium spheroidizing agent in the cored wire. The amount of ferrosilicon rare earth magnesium spheroidizing agent added is 0.6-0.1% of the total weight of the molten iron. Then, the wire feeder feeds it into the bottom of the transfer ladle to achieve the purpose of spheroidization. Step 4: Casting and molding. The strengthened molten iron is poured into a pre-made mold and heated in a stepwise uniform manner at 100℃ / min to between 850℃ and 900℃. The temperature is held for 1-2 hours. Then, the temperature is heated again in a stepwise uniform manner at 100℃ / min to between 1050℃ and 1100℃. The temperature is held for 2-3 hours. The pump casing is then removed and quickly immersed in cooling oil for 20-30 minutes to complete the heating and quenching of the inner shell of the mold. After that, it is removed and cooled to improve its metallographic properties.

7. The method for producing a corrosion-resistant and high-pressure-resistant thin-walled pump casing according to claim 6, characterized in that, In step two, the tapping temperature of the molten iron is maintained at 1500℃-1550℃; in step three, the temperature of the molten iron in the transfer ladle is maintained at 1450℃-1500℃; and in step four, the casting temperature is maintained at 1350℃-1400℃.

8. The method for producing a corrosion-resistant and high-pressure-resistant thin-walled pump casing according to claim 6, characterized in that, In step four, when pouring molten iron, a special pouring cup is prepared in advance, bottom pouring is implemented, a special ceramic tube pouring channel is installed, and a special filter screen is installed to ensure that the molten iron rises evenly during pouring.

9. The method for producing a corrosion-resistant and high-pressure-resistant thin-walled pump casing according to claim 6, characterized in that, In step four, when making the mold, a special core is used. After the clay core is assembled, the core is placed as a whole to ensure that the clay core is flawless. The appearance is also carefully controlled in terms of shaping, flow coating, brushing, cleaning flow marks, and baking to ensure the product's appearance.

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