Preparation process and application of high-carbon 17-4PH stainless steel powder

Abstract

The invention discloses a preparation process and application of high-carbon 17-4PH stainless steel powder, and relates to the technical field of powder metallurgy material preparation, and the powder is prepared from the following production raw materials by weight: 14-15% of industrial pure iron; 55%-58% of waste 304 stainless steel; 3%-4% of waste 316L stainless steel; 5%-7% of high carbon ferro-chrome; 6%-7% of micro-carbon ferrochrome; 0.7%-0.8% of metal molybdenum; 1%-2% of electrolytic manganese; 0.3%-0.6% of ferroniobium; and 9%-11% of electrolytic copper. According to the high-carbon 17-4PH stainless steel material and the preparation method thereof, the carbon content in the material is increased by filling high-carbon ferrochrome, so that the application performance of the 17-4 stainless steel material in the aspects of hardness and strength is improved, the preparation requirements of parts with higher hardness, strength and wear resistance are met, meanwhile, certain corrosion resistance of the material is kept, and the high-carbon 17-4PH stainless steel material has wider application fields.

Description

Technical Field

[0001] The present invention relates to the technical field of powder metallurgy material preparation, and specifically to a preparation process and application of high-carbon 17-4PH stainless steel powder. Background Art

[0002] 17-4PH stainless steel is a martensitic precipitation-hardening stainless steel with high strength and high corrosion resistance. Its main chemical components include chromium (Cr), nickel (Ni), copper (Cu), and a small amount of carbon (C), niobium (Nb) / columbium, manganese (Mn), silicon (Si), phosphorus (P), sulfur (S), etc. Among them, chromium, nickel, and copper are its main alloying elements, which play a decisive role in the properties of the material. The performance characteristics of 17-4PH stainless steel include: high strength and hardness, excellent corrosion resistance, good heat treatment performance, good workability and weldability, and stable high-temperature performance. It is widely used in many fields and occupies an important position, including but not limited to aerospace, ocean engineering, nuclear industry, chemical industry, medical devices and other fields.

[0003] The carbon content of 17-4PH stainless steel is usually below 0.07%. Although carbon is a key element to improve the strength and hardness of stainless steel, too high a carbon content may reduce its corrosion resistance and may have an adverse impact on the overall performance of the material. In current practical applications, the hardness of stainless steel is usually not improved by deliberately increasing the carbon content, but by other means to improve the material properties, such as adjusting the alloying element content (increasing the content of nickel can improve the corrosion resistance and toughness of the material, increasing the content of copper can improve the strength and hardness of the material), optimizing the heat treatment process (such as solution treatment, precipitation hardening treatment, etc. to further optimize the mechanical properties and corrosion resistance of the material), surface treatment technology (such as pickling, passivation treatment, which can improve the surface finish and corrosion resistance of the material), and so on.

[0004] In the actual application process, the production of some components requires 17-4PH stainless steel materials with higher strength, higher hardness and wear resistance while maintaining a certain corrosion resistance, such as cutting tools, bearings, valve components, pump parts, aerospace components, etc. Therefore, it is necessary to prepare 17-4PH stainless steel materials with more excellent performance to meet the market demand. Summary of the Invention

[0005] To solve the above-mentioned existing technical problems, the present invention provides a preparation process and application of high-carbon 17-4PH stainless steel powder, which greatly increases the carbon content in the material while maintaining the corrosion resistance of the material, making the material have high performance with higher strength, hardness and wear resistance, and having a wider application field.

[0006] To achieve the above object, the technical solution adopted by the present invention is: First aspect: The present invention provides a high-carbon 17-4PH stainless steel powder, which is prepared from the following production raw materials by weight percentage: industrial pure iron 14%-15%; waste 304 stainless steel 55%-58%; waste 316L stainless steel 3%-4%; high-carbon ferrochrome 5%-7%; micro-carbon ferrochrome 6%-7%; metallic molybdenum 0.7%-0.8%; electrolytic manganese 1%-2%; ferroniobium 0.3%-0.6%; electrolytic copper 9%-11%. Second aspect: The present invention provides a preparation method of a high-carbon 17-4PH stainless steel powder, which comprises the following steps: 1) Weigh the required production raw materials by weight percentage; 2) Use an intermediate frequency melting furnace. After starting, first add industrial pure iron, waste 304 stainless steel and electrolytic copper, and gradually add waste 316L sheet material after complete melting; 3) When the molten steel in the melting reaches half of the volume of the intermediate frequency melting furnace, add high-carbon ferrochrome and micro-carbon ferrochrome. The molten steel should cover the two added ferrochromes, and the feeding method is batch feeding; 4) After the two added ferrochromes are completely melted, gradually add the remaining waste 304 stainless steel. When the molten steel in the melting reaches 2 / 3 of the volume of the intermediate frequency melting furnace, evenly disperse and add ferroniobium; 5) After adding the remaining waste 304 stainless steel, wait for the steel material to be completely melted, and then cover it with a slag removing agent. At this time, the furnace is still continuously heated. When the temperature of the molten steel reaches 1630-1640°C, slagging is carried out. After slagging, measure the temperature. When the temperature of the molten steel is 1640-1650°C, add a deoxidizer, and then add a slag removing agent to cover the deoxidizer. Reduce the power to 30-40KW, keep it for 1-2 minutes and then carry out slagging until the slag in the furnace is completely removed; 6) Keep the molten steel after slagging at 1630-1650°C for pouring. During pouring, the atomization pressure of the high-pressure pump is kept at 110-120MPa. The atomized powder is dehydrated, and then vacuum dried. The drying temperature is set at 150-200°C and the time is set to 3-4 hours; 7) Screen the obtained dried powder with a sieve; 8) The screened powder is batch-mixed, sampled and tested. After passing the test, it is packaged and stored in the warehouse. The test result shows that the carbon content is higher than 0.4%, and the hardness of the sample block after heat treatment test is higher than HRC 50.

[0007] In step 2), if starting from a cold furnace, start with low power and gradually increase the power later; if starting from a hot furnace, start with full power.

[0008] In step 5), use an air gun to clean the residue in the pouring port during the last slagging.

[0009] In step 2), if starting from a cold furnace, start with low power and gradually increase the power later; if starting from a hot furnace, start with full power.

[0010] In a third aspect, the present invention provides an application of high-carbon 17-4PH powder in the field of preparing components with high hardness, strength and wear resistance.

[0011] The present invention describes a preparation method and application of 17-4PH stainless steel powder with a high carbon content. By adding high-carbon ferrochrome to increase the carbon content in the material, the application performance of the 17-4 stainless steel material in terms of hardness and strength is improved, so as to meet the preparation requirements of components with higher hardness, strength and wear resistance. At the same time, a certain corrosion resistance of the material is maintained, enabling the high-carbon 17-4PH stainless steel material to have a wider application field.

[0012] Specifically, in the present invention, the carbon content exceeds 0.4%, far exceeding the content of <0.07% in the existing 17-4PH stainless steel material, greatly improving the strength and hardness of the material. After testing, the hardness HRC exceeds 50; among other components, the chromium content is high, which is the key element to improve the corrosion resistance of stainless steel; the contents of nickel, copper and niobium elements are also at high values compared with the prior art, playing an auxiliary role in the corrosion resistance of the material; especially the high copper content improves the acid corrosion resistance of the material to sulfuric acid, phosphoric acid, etc., and can promote the stability of the passivation film; the high content of niobium combines with carbon to form niobium carbide, reducing the formation of chromium carbide, avoiding intergranular corrosion, preventing sensitization, and improving the intergranular corrosion resistance of the material. Specific embodiments

[0013] The present invention will be described in detail below with reference to specific embodiments: A high-carbon 17-4PH stainless steel powder is prepared from the following production raw materials by weight percentage: 14%-15% of industrial pure iron; 55%-58% of waste 304 stainless steel; 3%-4% of waste 316L stainless steel; 5%-7% of high-carbon ferrochrome; 6%-7% of micro-carbon ferrochrome; 0.7%-0.8% of metal molybdenum; 1%-2% of electrolytic manganese; 0.3%-0.6% of ferroniobium; 9%-11% of electrolytic copper. A preparation method of high-carbon 17-4PH stainless steel powder includes the following steps: 1) Weigh the required production raw materials according to the weight percentage; 2) Use an intermediate frequency melting furnace. After starting, first add industrial pure iron, waste 304 stainless steel and electrolytic copper, and gradually add waste 316L sheet material after complete melting; 3) When the molten steel in the intermediate frequency melting furnace reaches half of the inner volume, add high-carbon ferrochrome and micro-carbon ferrochrome. The molten steel should cover the two kinds of ferrochrome added, and the feeding method is batch addition; 4) After the two kinds of ferrochrome added are completely melted, gradually add the remaining waste 304 stainless steel, and disperse and evenly add ferroniobium when the molten steel in the intermediate frequency melting furnace reaches 2 / 3 of the inner volume; 5) After adding the remaining waste 304 stainless steel, wait for the steel materials to completely melt, and then cover them with slag remover. At this time, the furnace is still continuously heated. When the temperature of the molten steel reaches 1630 - 1640 °C, slagging is carried out. After slagging, the temperature is measured. When the temperature of the molten steel is 1640 - 1650 °C, deoxidizer is added, and then slag remover is added to cover the deoxidizer. The power is reduced to 30 - 40 KW, and after maintaining for 1 - 2 minutes, slagging is carried out again until the slag in the furnace is completely removed; 6) Keep the molten steel after slagging at 1630 - 1650 °C for pouring. During pouring, the atomization pressure of the high-pressure pump is maintained at 110 - 120 MPa. The atomized powder is dehydrated, and then vacuum dried. The drying temperature is set at 150 - 200 °C, and the time is set to 3 - 4 hours; 7) Screen the obtained dry powder through a sieve; 8) The screened powder is batch-mixed, sampled and tested. After passing the test, it is packaged and stored in the warehouse. The test results show that the carbon content is higher than 0.4%, and the hardness of the sample block after heat treatment test is higher than HRC 50.

[0014] As a preferred method, in this embodiment, in step 5), the residue in the pouring port is cleaned with an air gun during the last slagging.

[0015] As a preferred method, in step 2), if starting with a cold furnace pneumatically, start with a low power and gradually increase the power later; if starting with a hot furnace, start with full power.

[0016] The present invention provides an application of high-carbon 17 - 4PH powder in the field of preparing high-hardness, high-strength and wear-resistant parts, such as specific applications like cutting tools, bearings, valve components, pump parts, aerospace components, etc.

[0017] Example 1: 1) Weigh the required production raw materials by weight percentage: industrial pure iron 14%; waste 304 stainless steel 57%; waste 316L stainless steel 3%; high-carbon ferrochrome 6%; micro-carbon ferrochrome 65%; metallic molybdenum 0.7%; electrolytic manganese 2%; ferro-niobium 0.3%; electrolytic copper 10.5%; 2) Use an intermediate frequency melting furnace. After starting, first add industrial pure iron, waste 304 stainless steel and electrolytic copper. After complete melting, gradually add waste 316L sheet materials; 3) When the molten steel in the melting reaches half of the volume of the intermediate frequency melting furnace, add high-carbon ferrochrome and micro-carbon ferrochrome. The molten steel should cover the two added ferrochromes, and the feeding method is batch addition; 4) After the two added ferrochromes are completely melted, gradually add the remaining waste 304 stainless steel. When the molten steel in the melting reaches 2 / 3 of the volume of the intermediate frequency melting furnace, add ferro-niobium evenly; 5) After adding the remaining waste 304 stainless steel, wait for the steel material to completely melt, then cover it with slag remover. At this time, the furnace is still continuously heated. When the temperature of the molten steel reaches 1630 °C, slagging is carried out. After slagging, the temperature is measured. When the temperature of the molten steel is 1650 °C, deoxidizer is added, and then slag remover is added to cover the deoxidizer. The power is reduced to 30 KW and kept for 2 minutes, and then slagging is carried out. Finally, the slag in the furnace is completely removed; 6) Keep the molten steel after slagging at 1630 °C for pouring. During pouring, the atomization pressure of the high-pressure pump is kept at 120 MPa. The atomized powder is dehydrated, and then vacuum dried. The drying temperature is set at 200 °C and the time is set at 3 hours; 7) The obtained dried powder is screened by a sieve; 8) The screened powder is batch-mixed, sampled and tested. After passing the test, it is packaged and stored in the warehouse. The test result shows that the carbon content is 0.4089%, and the hardness of the sample block after heat treatment test is HRC 53.5.

[0018] Example 2: 1) Weigh the required production raw materials by weight percentage: industrial pure iron 14.6%; waste 304 stainless steel 55%; waste 316L stainless steel 4%; high-carbon ferrochrome 7%; micro-carbon ferrochrome 6%; metal molybdenum 08%; electrolytic manganese 1%; ferro-niobium 0.6%; electrolytic copper 11%; 2) Use an intermediate frequency melting furnace. After starting, first add industrial pure iron, waste 304 stainless steel and electrolytic copper. After completely melting, gradually add waste 316L sheet materials; 3) When the molten steel in the melting reaches half of the volume of the intermediate frequency melting furnace, add high-carbon ferrochrome and micro-carbon ferrochrome. The molten steel should cover the two kinds of ferrochrome added. The feeding method is batch feeding; 4) After the two kinds of ferrochrome added are completely melted, gradually add the remaining waste 304 stainless steel. When the molten steel in the melting reaches 2 / 3 of the volume of the intermediate frequency melting furnace, add ferro-niobium evenly; 5) After adding the remaining waste 304 stainless steel, wait for the steel material to completely melt, then cover it with slag remover. At this time, the furnace is still continuously heated. When the temperature of the molten steel reaches 1640 °C, slagging is carried out. After slagging, the temperature is measured. When the temperature of the molten steel is 1645 °C, deoxidizer is added, and then slag remover is added to cover the deoxidizer. The power is reduced to 40 KW and kept for 1 minute, and then slagging is carried out. Finally, the slag in the furnace is completely removed; 6) Keep the molten steel after slagging at 1640 °C for pouring. During pouring, the atomization pressure of the high-pressure pump is kept at 110 MPa. The atomized powder is dehydrated, and then vacuum dried. The drying temperature is set at 150 °C and the time is set at 4 hours; 7) The obtained dried powder is screened by a sieve; 8) The sieved powder is batch - mixed, sampled for testing, and after passing the test, it is packaged and stored in the warehouse. The test result shows that the carbon content is 0.4162%, and the hardness of the sample block after heat treatment test is HRC 52.2.

[0019] Example 3: 1) Weigh the required production raw materials by weight percentage: 15% industrial pure iron; 58% waste 304 stainless steel; 3.6% waste 316L stainless steel; 5% high - carbon ferrochrome; 7% micro - carbon ferrochrome; 0.75% molybdenum metal; 1.25% electrolytic manganese; 0.4% ferro - niobium; 9% electrolytic copper. 2) Use an intermediate - frequency melting furnace. After starting, first add industrial pure iron, waste 304 stainless steel, and electrolytic copper. After complete melting, gradually add waste 316L sheet materials. 3) When the molten steel in the intermediate - frequency melting furnace reaches half of its volume, add high - carbon ferrochrome and micro - carbon ferrochrome. The molten steel should cover the two added ferrochromes. The feeding method is batch - wise addition. 4) After the two added ferrochromes are completely melted, gradually add the remaining waste 304 stainless steel. When the molten steel in the intermediate - frequency melting furnace reaches 2 / 3 of its volume, evenly disperse and add ferro - niobium. 5) After adding the remaining waste 304 stainless steel, wait for the steel materials to completely melt, then cover with a slag - removing agent. At this time, the furnace is still continuously heated. When the temperature of the molten steel reaches 1635 °C, slag - tapping is carried out. After slag - tapping, the temperature is measured. When the temperature of the molten steel is 1640 °C, a deoxidizer is added, and then a slag - removing agent is added to cover the deoxidizer. The power is reduced to 35 KW, and after maintaining for 1.5 minutes, slag - tapping is carried out again until all the slag in the furnace is completely removed. 6) Keep the molten steel at 1650 °C for pouring. During pouring, the atomization pressure of the high - pressure pump is maintained at 115 MPa. The atomized powder is dehydrated, and then vacuum - dried. The drying temperature is set at 160 °C, and the time is set to 3.6 hours. 7) The obtained dried powder is screened through a sieve. 8) The sieved powder is batch - mixed, sampled for testing, and after passing the test, it is packaged and stored in the warehouse. The test result shows that the carbon content is 0.4224%, and the hardness of the sample block after heat treatment test is HRC 55.2.

[0020] Example 4: 1) Weigh the required production raw materials by weight percentage: 14.4% industrial pure iron; 57% waste 304 stainless steel; 3.4% waste 316L stainless steel; 6% high - carbon ferrochrome; 6.65% micro - carbon ferrochrome; 0.76% molybdenum metal; 1.33% electrolytic manganese; 0.46% ferro - niobium; 10% electrolytic copper. 2) Use an intermediate - frequency melting furnace. After starting, first add industrial pure iron, waste 304 stainless steel, and electrolytic copper. After complete melting, gradually add waste 316L sheet materials. 3) When the molten steel in the medium-frequency melting furnace reaches half of its internal volume, high-carbon ferrochrome and micro-carbon ferrochrome are added. The molten steel should cover the two kinds of ferrochrome added. The feeding method is to add in batches. 4) After the two kinds of ferrochrome added are completely melted, the remaining waste 304 stainless steel is gradually added. When the molten steel in the medium-frequency melting furnace reaches 2 / 3 of its internal volume, ferrocolumbium is added evenly and dispersedly. 5) After all the remaining waste 304 stainless steel is added, wait for the steel materials to be completely melted, and then cover with slag remover. At this time, the furnace is still continuously heated. When the temperature of the molten steel reaches 1638 °C, slagging is carried out. After slagging, the temperature is measured. When the temperature of the molten steel is 1645 °C, a deoxidizer is added, and then a slag remover is added to cover the deoxidizer. The power is reduced to 35 KW and kept for 1.8 minutes, and then slagging is carried out until the slag in the furnace is completely removed. 6) The molten steel after slagging is kept at 1645 °C for pouring. When pouring, the atomization pressure of the high-pressure pump is kept at 118 MPa. The atomized powder is dehydrated, and then vacuum dried. The drying temperature is set at 180 °C and the time is set at 3.8 hours. 7) The obtained dried powder is screened by a sieve. 8) The screened powder is batch-mixed, sampled and tested. After passing the test, it is packaged and stored in the warehouse. The test result shows that the carbon content is 0.4173%, and the hardness HRC of the sample block test after heat treatment is 50.4.

[0021] Comparative example: 17-4PH stainless steel powder is prepared according to the existing technology method, which meets the existing standards of each element content.

[0022] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the scope of the essence of the present invention should also fall within the protection scope of the present invention.

Claims

1. A high-carbon 17-4PH stainless steel powder, characterized in that, It is prepared from the following production raw materials by weight percentage: 14%-15% of industrial pure iron; 55%-58% of waste 304 stainless steel; 3%-4% of waste 316L stainless steel; 5%-7% of high-carbon ferrochrome; 6%-7% of micro-carbon ferrochrome; 0.7%-0.8% of metallic molybdenum; 1%-2% of electrolytic manganese; 0.3%-0.6% of ferroniobium; 9%-11% of electrolytic copper.

2. The preparation method of a high-carbon 17-4PH stainless steel powder as described in claim 1, characterized in that, It includes the following steps: 1) Weigh the required production raw materials according to the weight percentage. 2) Use an intermediate frequency melting furnace. After starting, first add industrial pure iron, waste 304 stainless steel and electrolytic copper. After complete melting, gradually add waste 316L sheet material. 3) When the molten steel in the intermediate frequency melting furnace reaches half of its volume, add high-carbon ferrochrome and micro-carbon ferrochrome. The molten steel should cover the two added ferrochromes. The feeding method is in batches. 4) After the two added ferrochromes are completely melted, gradually add the remaining waste 304 stainless steel. When the molten steel in the intermediate frequency melting furnace reaches 2 / 3 of its volume, evenly disperse and add ferroniobium. 5) After adding the remaining waste 304 stainless steel, wait for the steel material to completely melt, and then cover it with a slag removing agent. At this time, the furnace is still continuously heated. When the temperature of the molten steel reaches 1630-1640 °C, slagging is carried out. After slagging, measure the temperature. When the temperature of the molten steel is 1640-1650 °C, add a deoxidizer, and then add a slag removing agent to cover the deoxidizer. Reduce the power to 30-40 KW, keep it for 1-2 minutes and then carry out slagging until the slag in the furnace is completely removed. 6) Keep the molten steel after slagging at 1630-1650 °C for pouring. During pouring, the atomization pressure of the high-pressure pump is kept at 110-120 MPa. The atomized powder is dehydrated, and then vacuum dried. The drying temperature is set at 150-200 °C, and the time is set to 3-4 hours. 7) Screen the obtained dried powder through a sieve. 8) The screened powder is batch-mixed, sampled and tested. After passing the test, it is packaged and stored in the warehouse. The test result shows that the carbon content is higher than 0.4%, and the hardness of the sample block tested by heat treatment is higher than HRC 50.

3. The preparation method of a high-carbon 17-4PH stainless steel powder according to claim 2, characterized in that, In step 5), the residue in the pouring port is cleaned with an air gun during the last slagging.

5. The preparation method of a high-carbon 17-4PH stainless steel powder according to claim 2, characterized in that, in step 2), if starting from a cold furnace pneumatically, start with a low power and gradually increase the power later; if starting from a hot furnace, start with full power.

4. The application of the high-carbon 17-4PH powder according to any one of claims 1-4 in the field of preparing high-hardness, high-strength and wear-resistant parts.

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