Powder metallurgy low-nickel non-magnetic stainless steel powder and preparation method thereof

Abstract

The invention relates to powder metallurgy low-nickel non-magnetic stainless steel powder and a preparation method thereof.The powder metallurgy low-nickel non-magnetic stainless steel powder comprises, by mass, 1.3%-1.4% of carbon, 0.6%-1.0% of silicon, 10%-13% of manganese, smaller than or equal to 0.04% of sulfur, smaller than or equal to 0.04% of phosphorus, 19%-21% of chromium, 1.0%-2.0% of nickel, smaller than or equal to 0.5% of oxygen and the balance ferrum. The atomizing barrel is filled with inert gas, and air is exhausted to prevent powder from being oxidized; high-pressure water is adopted as an atomizing medium, and molten steel obtained after deoxidation and deslagging is atomized into stainless steel powder through a powder making device; and finally, the stainless steel powder obtained through atomization is subjected to dewatering and drying treatment, moisture of metal powder is removed, then screening and grading treatment is conducted, and the low-nickel non-magnetic stainless steel powder is obtained.The magnetic problem of existing 201 stainless steel powder and products thereof is solved by accurately controlling chemical components and optimizing the production process, meanwhile, the material cost is reduced, and the production efficiency is improved. And the application field of the stainless steel material is widened.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, and in particular to a powder metallurgy low-nickel non-magnetic stainless steel powder and a preparation method thereof. Background Art

[0002] Stainless steel materials have been widely used in industry and daily life due to their excellent corrosion resistance and good processing properties. 201 stainless steel, as an economical austenitic stainless steel, provides good forming properties and corrosion resistance with its low carbon content and relatively high chromium and nickel content. It is widely used in architectural decoration, household goods, automotive parts and other fields. However, traditional 201 stainless steel has certain limitations in powder metallurgy process. Due to the characteristics of powder metallurgy process, 201 stainless steel powder and its products have strong magnetism, which limits the application of this product. Therefore, the development of a low-nickel non-magnetic stainless steel powder can not only meet the needs of cost-effectiveness, but also overcome the magnetic problems caused by powder metallurgy process, which has important industrial value and market potential. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a powder metallurgy low-nickel non-magnetic stainless steel powder and a preparation method thereof.

[0004] The present invention is achieved through the following technical scheme, providing a powder metallurgy low-nickel non-magnetic stainless steel powder, which has the following composition by mass percentage: carbon: 1.3-1.4%, silicon: 0.6-1.0%, manganese: 10-13%, sulfur ≤0.04%, phosphorus ≤0.04%, chromium: 19-21%, nickel: 1.0-2.0%, oxygen ≤0.5%, and the balance is iron.

[0005] A method for preparing a powder metallurgy low-nickel non-magnetic stainless steel powder comprises the following steps: S1. Smelting the raw materials in a medium frequency furnace and deoxidizing and deslagging the molten steel; S2. Fill the atomizing barrel with inert gas and exclude air to prevent powder oxidation; S3, using high-pressure water as atomizing medium, atomizing the deoxidized and deslagging molten steel into stainless steel powder through a powder making device; S4. Dehydrating and drying the stainless steel powder obtained by atomization to remove moisture from the metal powder, and then sieving and grading the powder to obtain low-nickel non-magnetic stainless steel powder.

[0006] As an optimization, step S1 includes the following steps: first, adding raw materials other than silicon into the medium frequency furnace, heating to 1200°C, after the molten steel is dissolved, heating to 1500-1580°C, melting, adding silicon, alloying, adding deoxidizer, slagging, standing for 3-5 minutes, allowing the slag to float, then removing the slag, adding deoxidizer again, until no slag is generated, heating to 1580-1600°C, and performing steel tapping atomization As an optimization, the inert gas in step S2 is nitrogen or argon.

[0007] As an optimization, step S3 includes the following steps: the high-pressure atomizing pump is turned on in the pressure test mode, the pressure is tested, and after the flow rate is stable, the pressure is increased to 10-20 MPa; an annular seam spray disc is used, the angle of the atomizing spray disc is 40°-30°, the diameter of the molten steel guide pipe is 3.5 mm, and the flow rate of the molten steel is 8-10 kg / min; the pump operation is stopped 3 minutes after the pouring of the molten steel in the leaking ladle is completed, and the inert gas is turned off after 5 minutes.

[0008] As an optimization, step S4 includes the following steps: introducing the mixed slurry of atomized stainless steel powder and water into a centrifugal dehydrator for dehydration; placing the dehydrated stainless steel powder into a hot air dryer for drying at a drying temperature of 120°C.

[0009] As an optimization, nitrogen is flushed into the mixed slurry of the stainless steel powder and water, and then introduced into a centrifugal dehydrator.

[0010] The beneficial effects of the present invention are as follows: the powder metallurgy low-nickel non-magnetic stainless steel powder and the preparation method thereof solve the magnetic problem of the existing 201 stainless steel powder and its products by accurately controlling the chemical composition and optimizing the production process, while reducing the material cost and broadening the application field of the stainless steel material. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A flow chart is prepared for the present invention; DETAILED DESCRIPTION In order to clearly illustrate the technical features of this solution, this solution is described below through a specific implementation method.

[0012] like Figure 1 As shown, a powder metallurgy low-nickel non-magnetic stainless steel powder of the present invention includes the following compositions by mass percentage: carbon: 1.3-1.4%, silicon: 0.6-1.0%, manganese: 10-13%, sulfur ≤0.04%, phosphorus ≤0.04%, chromium: 19-21%, nickel: 1.0-2.0%, oxygen ≤0.5%, and the balance is iron. The raw materials can be obtained from scrap steel. By calculating the material components in each scrap steel, suitable scrap steel is smelted to make low-nickel non-magnetic stainless steel powder.

[0013] The stainless steel iron powder prepared with this formula has greatly reduced magnetism compared to existing stainless steel iron powder, thereby improving its application scenarios.

[0014] A method for preparing a powder metallurgy low-nickel non-magnetic stainless steel powder comprises the following steps: S1. First add raw materials except silicon into the medium frequency furnace. If scrap steel is used as raw material, the silicon content in the initial scrap steel should be less than the required silicon content, so as to facilitate the subsequent addition of silicon. Heat up to 1200℃. After the molten steel is dissolved, heat up to 1500-1580℃, melt it, and add silicon. Since silicon is a strong reducing agent, adding silicon as a reducing agent during steelmaking can reduce the oxide in the iron ore to metallic iron. At high temperature, this can reduce the oxygen content, increase the oxygen content in the slag, and promote the iron smelting reaction to proceed.

[0015] After alloying, add deoxidizer, slag, let it stand for 3-5 minutes to allow the slag to float, then remove the slag, add deoxidizer again until no slag is generated, heat to 1580-1600℃, pour the molten steel into the ladle, transport it by transport vehicle, and then carry out subsequent steel tapping atomization.

[0016] S2. Fill the atomizing barrel with inert gas and exclude air to prevent oxidation of the powder. The inert gas is nitrogen or argon.

[0017] S3, using high-pressure water as the atomizing medium, the high-pressure atomizing pump is turned on the pressure test mode, the pressure is tested, and after the flow rate is stable, the pressure is increased to 10-20MPa; an annular seam spray disc is used, the angle of the atomizing spray disc is 40°-30°, the diameter of the molten steel guide pipe is 3.5mm, and the flow rate of the molten steel is 8-10kg / min; the pump operation is stopped 3 minutes after the molten steel pouring in the ladle is completed, and the inert gas is turned off after 5 minutes, so that the deoxidized and deslagging molten steel is atomized into stainless steel powder through the powder making device; S4. Nitrogen is flushed into the mixed slurry of atomized stainless steel powder and water, and then introduced into a centrifugal dehydrator for dehydration and drying to remove moisture from the metal powder. The dehydrated stainless steel powder is placed in a hot air dryer for drying at a drying temperature of 120°C. Then screening and grading are performed to obtain low-nickel non-magnetic stainless steel powder, which is finally sealed and packaged.

[0018] Of course, the above description is not limited to the above examples. Technical features not described in the present invention can be achieved by or by using existing technologies, which will not be described here. The above embodiments and drawings are only used to illustrate the technical scheme of the present invention and are not limitations of the present invention. The present invention is described in detail with reference to the preferred implementation methods. Ordinary technicians in this field should understand that changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention do not depart from the purpose of the present invention, and should also fall within the scope of protection of the claims of the present invention.

Claims

1. A powder metallurgy low-nickel non-magnetic stainless steel powder, characterized in that: The composition, by mass percentage, is as follows: carbon: 1.3-1.4%, silicon: 0.6-1.0%, manganese: 10-13%, sulfur ≤0.04%, phosphorus ≤0.04%, chromium: 19-21%, nickel: 1.0-2.0%, oxygen ≤0.5%, and the balance is iron.

2. A method for preparing the powder metallurgy low-nickel non-magnetic stainless steel powder according to claim 1, characterized in that: The steps include: S1. Smelting each raw material in a medium frequency furnace and deoxidizing and deslagging the molten steel; S2. Fill the atomizing barrel with inert gas and exclude air to prevent powder oxidation; S3, using high-pressure water as atomizing medium, atomizing the deoxidized and deslagging molten steel into stainless steel powder through a powder making device; S4. Dehydrating and drying the stainless steel powder obtained by atomization to remove moisture from the metal powder, and then sieving and grading the powder to obtain low-nickel non-magnetic stainless steel powder.

3. The preparation method according to claim 2, characterized in that: The step S1 comprises the following steps: firstly, adding raw materials except silicon into the medium frequency furnace, heating to 1200°C, heating to 1500-1580°C after the molten steel is dissolved, melting, adding silicon, alloying, adding deoxidizer, slagging, standing for 3-5 minutes to make the slag float, then removing the slag, adding deoxidizer again, until no slag is generated, heating to 1580-1600°C, and atomizing the steel.

4. The preparation method according to claim 2, characterized in that: The inert gas in step S2 is nitrogen or argon.

5. The preparation method according to claim 2, characterized in that: The step S3 comprises the following steps: starting the high-pressure atomizing pump in the pressure test mode, testing the pressure, and increasing the pressure to 10-20 MPa after the flow rate is stable; using an annular seam spray disc, the angle of the atomizing spray disc is 40°-30°, the diameter of the molten steel flow guide pipe is 3.5 mm, and the flow rate of the molten steel is 8-10 kg / min; stopping the pump operation 3 minutes after the molten steel pouring in the leaking ladle is completed, and turning off the inert gas after 5 minutes.

6. The preparation method according to claim 2, characterized in that: The step S4 comprises the following steps: introducing the mixed slurry of the atomized stainless steel powder and water into a centrifugal dehydrator for dehydration; and placing the dehydrated stainless steel powder into a hot air dryer for drying at a drying temperature of 120°C.

7. The preparation method according to claim 6, characterized in that: Nitrogen is injected into the mixed slurry of the stainless steel powder and water, and then introduced into a centrifugal dehydrator.

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