17-4PH stainless steel powder and preparation method and application thereof

Abstract

The invention relates to the technical field of powder metallurgy material preparation, and particularly discloses 17-4PH stainless steel powder and a preparation method and application thereof. The high-strength and high-toughness alloy material comprises the following raw material components in percentage by weight: 16.0%-17.5% of Cr, 3.5%-4.5% of Ni, 3.5%-5.0% of Cu, 0.25%-0.45% of Mo, 0.25%-0.55% of Nb, 0.01%-0.05% of C, 0.20%-0.60% of Si, 0.10%-0.60% of Mn and 72%-75% of Fe. According to the 17-4PH stainless steel powder and the preparation method thereof, the types and proportions of all the raw material components are reasonably adjusted, the pouring temperature and the water temperature of water atomization are strictly adjusted and controlled, and the prepared 17-4PH stainless steel powder has the beneficial effects of being good in sphericity degree, high in tap density, good in feeding fluidity and good in green body weight stability.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy material preparation, and in particular to a 17-4PH stainless steel powder and a preparation method and application thereof. Background Art

[0002] As a stainless steel material with high strength and strong corrosion resistance, 17-4PH stainless steel parts made by powder injection molding are widely used in automobile parts manufacturing, household appliances, mechanical parts manufacturing, 3C electronic product parts, etc. At present, 17-4PH stainless steel powder for powder injection molding is usually prepared by mechanical ball milling, gas atomization, water atomization or water-gas combined atomization. Among them, (1) ball milling method: the advantage is that it can be produced continuously and is suitable for the preparation of powders of various metals and alloys; the disadvantage is that batch production is difficult and the powder morphology is irregular; (2) gas atomization method: the advantage is that the prepared powder has high sphericity and low oxygen content, and the disadvantage is that the powder particle size is coarse, hollow spheres, and high production cost; (3) water-gas combined atomization method: the powder has the advantage of fine powder particle size. However, the sphericity of 17-4PH stainless steel powder produced by water-gas combined atomization method is poor, and there are many irregular shaped particles, which leads to poor powder fluidity, so the density of the injection compact is low, resulting in low sintering density. The poor fluidity of the powder will also affect the dimensional stability of the injection blank, the sintering shrinkage rate will fluctuate greatly, and the dimensional accuracy of the sintered parts will be poor.

[0003] Therefore, it is necessary to provide a 17-4PH stainless steel powder and a preparation method and application thereof, improve the sphericity of the 17-4PH stainless steel powder, improve the tap density, feeding fluidity, and green weight stability of the powder, thereby improving the sintering shrinkage stability of metal powder injection molding parts and improving the dimensional accuracy of sintered parts. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a 17-4PH stainless steel powder and a preparation method and application thereof, which improves the sphericity of the 17-4PH stainless steel powder, improves the tap density, feed fluidity, and green weight stability of the powder, thereby improving the sintering shrinkage stability of metal powder injection molding parts (MIM parts) and improving the dimensional accuracy of sintered parts.

[0005] A first aspect of the present invention provides a 17-4PH stainless steel powder.

[0006] Specifically, a 17-4PH stainless steel powder includes the following raw material components, measured by weight percentage: Cr16.0-17.5%, Ni 3.5-4.5%, Cu 3.5-5.0%, Mo 0.25-0.45%, Nb 0.25-0.55%, C0.01-0.05%, Si 0.20-0.60%, Mn 0.10-0.60%, and Fe 72-75%.

[0007] Preferably, a 17-4PH stainless steel powder comprises the following raw material components, in weight percentage: Cr17.0-17.5%, Ni 3.5-4.5%, Cu 3.5-5.0%, Mo 0.25-0.45%, Nb 0.25-0.55%, C0.01-0.05%, Si 0.20-0.60%, Mn 0.10-0.60%, Fe 72-73.

[0008] Preferably, inevitable impurities are also included, and the inevitable impurities include P and S.

[0009] Preferably, by weight percentage, P is 0.001 to 0.035%, and S is 0.001 to 0.030%.

[0010] A second aspect of the present invention provides a method for preparing 17-4PH stainless steel powder.

[0011] Specifically, the following steps are included:

[0012] (1) Mixing and smelting the raw material components, adding a slag remover and a deoxidizer, standing the mixture to remove the slag, and obtaining a 17-4PH alloy melt;

[0013] (2) pouring the 17-4PH alloy melt obtained in step (1), atomizing the alloy, cooling the alloy, and solidifying the alloy to obtain a cooled powder;

[0014] (3) centrifugally dehydrating the powder obtained in step (2) after cooling to obtain a semi-finished wet powder, and drying to obtain 17-4PH stainless steel powder;

[0015] In step (2), the pouring temperature is 1660-1680°C;

[0016] In step (2), the water temperature of the water atomization powder making is 40-60°C.

[0017] Further preferably, the pouring temperature is 1670-1680°C.

[0018] More preferably, the pouring temperature is 1675-1680°C.

[0019] More preferably, the water temperature of the water atomization powder making is 45-55°C.

[0020] More preferably, the water temperature of the water atomization powder making is 48-55°C.

[0021] Preferably, in step (1), the temperature of the mixed smelting is 1650-1700°C.

[0022] Further preferably, in step (1), the temperature of the mixed smelting is 1660-1665°C.

[0023] Preferably, in step (1), the slag remover comprises calcium silicate particles.

[0024] Preferably, in step (1), the amount of the slag remover added is 0.20 to 0.40% of the total mass of the raw material components.

[0025] Further preferably, in step (1), the amount of the slag remover added is 0.25 to 0.35% of the total mass of the raw material components.

[0026] More preferably, in step (1), the amount of the slag remover added is 0.25% of the total mass of the raw material components.

[0027] Preferably, in step (1), the deoxidizer comprises metallic silicon particles.

[0028] Preferably, in step (1), the amount of the deoxidizer added is 0.15-0.35% of the total mass of the raw material components.

[0029] Further preferably, in step (1), the amount of the deoxidizer added is 0.20-0.30% of the total mass of the raw material components.

[0030] More preferably, in step (1), the amount of the deoxidizer added is 0.30% of the total mass of the raw material components.

[0031] Preferably, in step (1), the standing time is 1 to 3 minutes.

[0032] More preferably, in step (1), the standing time is 2 to 3 minutes.

[0033] More preferably, in step (1), the standing time is 2 minutes.

[0034] Preferably, in step (2), the pressure of the water atomization powder making is 110-140 MPa.

[0035] Further preferably, in step (2), the pressure of the water atomization powder making is 120-140 MPa.

[0036] More preferably, in step (2), the pressure of the water atomization powder making is 130-135 MPa.

[0037] Preferably, the water atomization spray plate for water atomization powder making contains 4 nozzles.

[0038] Preferably, in step (2), the 17-4PH alloy melt obtained in step (1) is poured into an atomizing tundish.

[0039] More preferably, the temperature inside the atomizing tundish is 1200-1400°C.

[0040] More preferably, the temperature inside the atomizing tundish is 1250-1350°C.

[0041] Preferably, in step (2), the water atomization powder making step also includes the 17-4PH alloy melt flowing out from the guide tube of the atomization tundish, and the flowing 17-4PH alloy melt is crushed by high-pressure water to obtain alloy powder droplets.

[0042] Further preferably, the guide tube is made of corundum or zirconium oxide.

[0043] More preferably, the guide tube is made of zirconium oxide.

[0044] Preferably, the diameter of the flow guide tube is 3.0-5.0 mm.

[0045] Further preferably, the diameter of the flow guide tube is 3.5-4.5 mm.

[0046] More preferably, the diameter of the flow guide tube is 3.5 mm.

[0047] Preferably, in step (3), the moisture content of the semi-finished wet powder is 6-10%.

[0048] Further preferably, in step (3), the moisture content of the semi-finished wet powder is 7-9%.

[0049] Preferably, in step (3), the drying time is 8 to 14 hours.

[0050] Further preferably, in step (3), the drying time is 10 to 12 hours.

[0051] Preferably, in step (3), the drying rotation speed is 8 to 12 rpm.

[0052] Further preferably, in step (3), the drying rotation speed is 10 to 11 rpm.

[0053] More preferably, in step (3), the drying speed is 10 rpm.

[0054] Preferably, the drying temperature is 160-175°C.

[0055] A third aspect of the present invention provides an application of 17-4PH stainless steel powder in the field of preparing precision parts.

[0056] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0057] The invention reasonably mixes the types and proportions of various raw material components, strictly controls the pouring temperature and the water temperature of water atomization, and obtains 17-4PH stainless steel powder with the characteristics of good sphericity, high tap density, good feeding fluidity and good green weight stability, which is beneficial to improving the sintering shrinkage stability of MIM parts and improving the dimensional accuracy of sintered parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a microscopic morphology analysis diagram of the 17-4PH stainless steel powder of Example 1 under a scanning electron microscope;

[0059] Figure 2 This is a microscopic morphology analysis diagram of the 17-4PH stainless steel powder of Example 2 under a scanning electron microscope;

[0060] Figure 3 This is a microscopic morphology analysis diagram of the 17-4PH stainless steel powder of Example 3 under a scanning electron microscope;

[0061] Figure 4 This is a microscopic morphology analysis diagram of the 17-4PH stainless steel powder of Comparative Example 1 under a scanning electron microscope;

[0062] Figure 5 This is a microscopic morphology analysis diagram of the 17-4PH stainless steel powder of Comparative Example 2 under a scanning electron microscope. DETAILED DESCRIPTION

[0063] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0064] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0065] Example 1

[0066] A 17-4PH stainless steel powder and a preparation method thereof.

[0067] The 17-4PH stainless steel powder comprises the following raw material components by weight percentage: Cr 17.2%, Ni 4.2%, Cu4.4%, Mo 0.35%, Nb 0.40%, C 0.02%, Si 0.40%, Mn 0.50%, Fe 72.525%;

[0068] The contents of inevitable impurities are P 0.002% and S 0.003%.

[0069] The specific preparation method is as follows:

[0070] (1) The raw material components were put into an induction furnace for mixed smelting at 1660° C. After all the materials were melted, 0.25% of the total weight of silicon calcium particles and 0.30% of metal silicon particles were added, and the mixture was allowed to stand for 2 minutes and slag was removed to obtain a 17-4PH alloy melt.

[0071] (2) The 17-4PH alloy melt obtained in step (1) is poured into an atomizing tundish at a pouring temperature of 1675°C and a temperature inside the atomizing tundish of 1250°C. The 17-4PH alloy melt then flows out from a guide tube of the atomizing tundish. The guide tube is made of zirconium oxide and has a diameter of 3.5 mm. The 17-4PH alloy melt is crushed by high-pressure water. The pressure of the high-pressure water (pressure of water atomization powder making) is 135 MPa and the temperature of the high-pressure water (water temperature of water atomization powder making) is 48°C. The water atomization spray plate has four nozzles to obtain alloy powder droplets. The alloy powder droplets are cooled and solidified to obtain a cooled powder.

[0072] (3) The powder obtained in step (2) is centrifugally dehydrated after cooling to obtain a semi-finished wet powder with a moisture content of 8%, and the semi-finished wet powder is vacuum dried for 12 hours at a speed of 10 rpm, and further ultrasonically vibrated screened and air flow graded to obtain a 17-4PH stainless steel powder with a specification of 500 mesh.

[0073] Example 2

[0074] A 17-4PH stainless steel powder and a preparation method thereof.

[0075] The 17-4PH stainless steel powder comprises the following raw material components by weight percentage: Cr 17.2%, Ni 4.2%, Cu4.4%, Mo 0.35%, Nb 0.40%, C 0.02%, Si 0.40%, Mn 0.50%, Fe 72.525%;

[0076] The contents of inevitable impurities are P 0.002% and S 0.003%.

[0077] The specific preparation method is as follows:

[0078] (1) The raw material components were put into an induction furnace for mixed smelting at 1660° C. After all the materials were melted, 0.25% of the total weight of silicon calcium particles and 0.30% of metal silicon particles were added, and the mixture was allowed to stand for 2 minutes and slag was removed to obtain a 17-4PH alloy melt.

[0079] (2) The 17-4PH alloy melt obtained in step (1) is poured into an atomizing tundish at a pouring temperature of 1675°C and a temperature inside the atomizing tundish of 1250°C. The 17-4PH alloy melt then flows out from a draft tube of the atomizing tundish. The draft tube is made of zirconium oxide and has a diameter of 3.5 mm. The 17-4PH alloy melt is crushed by high-pressure water. The pressure of the high-pressure water (pressure of water atomization powder making) is 135 MPa and the temperature of the high-pressure water (water temperature of water atomization powder making) is 55°C. The water atomization spray plate has four nozzles to obtain alloy powder droplets. The alloy powder droplets are cooled and solidified to obtain a cooled powder.

[0080] (3) The powder obtained in step (2) is centrifugally dehydrated after cooling to obtain a semi-finished wet powder with a moisture content of 8%, and the semi-finished wet powder is vacuum dried for 12 hours at a speed of 10 rpm, and further ultrasonically vibrated screened and air flow graded to obtain a 17-4PH stainless steel powder with a specification of 500 mesh.

[0081] Example 3

[0082] A 17-4PH stainless steel powder and a preparation method thereof.

[0083] The 17-4PH stainless steel powder comprises the following raw material components by weight percentage: Cr 17.2%, Ni 4.2%, Cu4.4%, Mo 0.35%, Nb 0.40%, C 0.02%, Si 0.40%, Mn 0.50%, Fe 72.525%;

[0084] The contents of inevitable impurities are P 0.002% and S 0.003%.

[0085] The specific preparation method is as follows:

[0086] (1) The raw material components were put into an induction furnace for mixed smelting at 1665° C. After all the materials were melted, 0.25% of the total weight of calcium silicon particles and 0.30% of metal silicon particles were added, and the mixture was allowed to stand for 2 minutes and slag was removed to obtain a 17-4PH alloy melt.

[0087] (2) The 17-4PH alloy melt obtained in step (1) is poured into an atomizing tundish at a pouring temperature of 1675°C and a temperature inside the atomizing tundish of 1250°C. The 17-4PH alloy melt then flows out from a draft tube of the atomizing tundish. The draft tube is made of zirconium oxide and has a diameter of 3.5 mm. The 17-4PH alloy melt is crushed by high-pressure water. The pressure of the high-pressure water (pressure of water atomization powder making) is 135 MPa and the temperature of the high-pressure water (water temperature of water atomization powder making) is 55°C. The water atomization spray plate has four nozzles to obtain alloy powder droplets. The alloy powder droplets are cooled and solidified to obtain a cooled powder.

[0088] (3) The powder obtained in step (2) is centrifugally dehydrated after cooling to obtain a semi-finished wet powder with a moisture content of 8%, and the semi-finished wet powder is vacuum dried for 12 hours at a speed of 10 rpm, and further ultrasonically vibrated screened and air flow graded to obtain a 17-4PH stainless steel powder with a specification of 500 mesh.

[0089] Comparative Example 1

[0090] A 17-4PH stainless steel powder and a preparation method thereof.

[0091] The difference from Example 1 is that the pouring temperature in step (2) of Comparative Example 1 is 1650°C.

[0092] Comparative Example 2

[0093] A 17-4PH stainless steel powder and a preparation method thereof.

[0094] The difference from Example 1 is that the water temperature of the water atomization in step (2) of Comparative Example 2 is 35°C.

[0095] 1. The 17-4PH stainless steel powder obtained in Examples 1 to 3 and Comparative Examples 1 to 2 was tested for performance: tap density (TD), oxygen content ([O]), and laser particle size distribution. The detailed results are shown in Table 1. TD: refer to GB / T 5162-2021; [O]: refer to GB / T 14265-2017; laser particle size distribution: refer to GB / T 19077-2016.

[0096] Table 1 Performance test results of 17-4PH stainless steel powder

[0097]

[0098]

[0099] It can be seen from Table 1 that the tap density of the 17-4PH stainless steel powders prepared in Examples 1 to 3 is higher than that in Comparative Examples 1 to 2.

[0100] 2. The microscopic morphology of the 17-4PH stainless steel powders of Examples 1 to 3 and Comparative Examples 1 to 2 was analyzed using a scanning electron microscope. Figures 1 to 5 .

[0101] As shown in the figure, Examples 1 to 3 are all nearly spherical under a scanning electron microscope, with better morphology, while Comparative Examples 1 to 2 have poor morphology, and there are more irregularly shaped 17-4PH stainless steel powders in Comparative Examples 1 to 2.

[0102] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution obtained by any modification, equivalent replacement, improvement, etc. made by a person skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection determined by the claims.

Claims

1. A 17-4PH stainless steel powder, It is characterized in that Calculated in weight percentage, the raw material components include: Cr 16.0-17.5%, Ni 3.5-4.5%, Cu 3.5-5.0%, Mo 0.25-0.45%, Nb 0.25-0.55%, C 0.01-0.05%, Si 0.20-0.60%, Mn 0.10-0.60%, and Fe 72-75%.

2. The 17-4PH stainless steel powder according to claim 1, It is characterized in that Calculated in weight percentage, the raw material components include: Cr 17.0-17.5%, Ni 3.5-4.5%, Cu 3.5-5.0%, Mo 0.25-0.45%, Nb 0.25-0.55%, C 0.01-0.05%, Si 0.20-0.60%, Mn 0.10-0.60%, Fe 72-73.

3. The 17-4PH stainless steel powder according to claim 1, It is characterized in that It also includes inevitable impurities, including P and S.

4. The 17-4PH stainless steel powder according to claim 3, It is characterized in that In terms of weight percentage, P 0.001~0.035%, S 0.001~0.030%.

5. The method for preparing the 17-4PH stainless steel powder according to any one of claims 1 to 4, It is characterized in that The following steps are involved: (1) Mixing and smelting the raw material components, adding a slag remover and a deoxidizer, standing the mixture to remove the slag, and obtaining a 17-4PH alloy melt; (2) pouring the 17-4PH alloy melt obtained in step (1), atomizing the alloy, cooling the alloy, and solidifying the alloy to obtain a cooled powder; (3) centrifugally dehydrating the powder obtained in step (2) after cooling to obtain a semi-finished wet powder, and drying to obtain 17-4PH stainless steel powder; In step (2), the pouring temperature is 1660-1680°C; In step (2), the water temperature of the water atomization powder making is 40-60°C.

6. The preparation method according to claim 5, It is characterized in that In step (1), the temperature of the mixed smelting is 1650-1700°C.

7. The preparation method according to claim 5, It is characterized in that In step (2), the pressure of the water atomization powder making is 110-140 MPa.

8. The preparation method according to claim 5, It is characterized in that In step (3), the moisture content of the semi-finished wet powder is 6-10%.

9. The preparation method according to claim 5, It is characterized in that In step (3), the drying time is 8 to 14 hours and the rotation speed is 8 to 12 rpm.

10. Use of the 17-4PH stainless steel powder according to any one of claims 1 to 4 in the field of preparing precision parts.

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