Method for strengthening and toughening wear-resistant martensitic stainless steel additive part

Abstract

The invention discloses a strengthening and toughening treatment method for a wear-resistant martensitic stainless steel additive part, and belongs to the field of metal alloys, and the treatment method comprises the following steps: carrying out homogenizing annealing treatment on a wear-resistant martensitic stainless steel sample in inert gas, then carrying out secondary annealing, and finally carrying out isothermal quenching to obtain the strengthened and toughened wear-resistant stainless steel additive part. According to the method, the technological process is simple, the period is short, the treatment method is easy to regulate and control, reinforcing and toughening treatment of the wear-resistant martensitic stainless steel additive part is achieved, and a new method is provided for strengthening and toughening treatment of alloy materials containing grain boundary network carbides and martensitic structures.

Description

Technical Field

[0001] The invention belongs to the technical field of metal alloy processing, and in particular relates to a method for strengthening and toughening a wear-resistant martensitic stainless steel additive component. Background Art

[0002] The economic losses caused by wear and corrosion failure of mechanical equipment are huge every year worldwide. In important application fields such as petrochemicals, mining exploration, aerospace, etc., in addition to certain requirements for corrosion resistance, structural parts also need sufficiently high strength, hardness and wear resistance. This exceeds the requirements that austenitic and ferritic stainless steels can meet, and martensitic stainless steel becomes a necessary choice. Additive manufacturing technology is based on digital models and prepares three-dimensional solid parts by stacking materials layer by layer. Additive manufacturing has become an important symbol of the third industrial revolution and has received great attention from countries around the world. Additive manufacturing technology has a forming principle that is completely different from traditional hot working technology, and its physical metallurgical process is very complicated. The complex residual stress of the alloy block, the phenomenon of difficult to control microstructure, and the brittleness of wear-resistant martensitic stainless steel additive parts seriously affect the quality of the alloy block and restrict the further application of additive manufacturing technology. Summary of the invention

[0003] In order to overcome the brittleness problem of wear-resistant martensitic stainless steel additive parts in the prior art, the purpose of the present invention is to provide a method for strengthening and toughening wear-resistant martensitic stainless steel additive parts, which can achieve strengthening and toughening of wear-resistant martensitic stainless steel additive parts and improve hardness under an inert gas protection atmosphere.

[0004] To achieve the purpose of the present invention, the technical solution adopted by the present invention is as follows: A method for strengthening and toughening a wear-resistant martensitic stainless steel additive component, comprising the following steps: The wear-resistant martensitic stainless steel sample was homogenized and annealed under inert gas, then subjected to secondary annealing, and finally to isothermal quenching to obtain a wear-resistant stainless steel additive part.

[0005] Furthermore, the temperature of the homogenization annealing treatment is 1000-1280︒C, and the holding time is calculated as no more than 150 min / mm thickness.

[0006] Further, the temperature is increased to 1000-1280︒C at a heating rate of 10-30︒C / min.

[0007] Furthermore, the wear-resistant martensitic stainless steel sample was homogenized and annealed under inert gas, cooled to room temperature in a furnace, and then subjected to secondary annealing.

[0008] Furthermore, the temperature of the secondary annealing is 800-1100°C, and the holding time is calculated as no more than 150 min / mm thickness.

[0009] Further, the temperature is increased to 800-1100︒C at a heating rate of 10-30︒C / min.

[0010] Furthermore, after the secondary annealing, the furnace is cooled to an isothermal quenching temperature for isothermal quenching.

[0011] Furthermore, the temperature of isothermal quenching is 300-600︒C, and the holding time is calculated as no more than 150 min / mm thickness.

[0012] Furthermore, the isothermal quenching is followed by air cooling to room temperature.

[0013] Furthermore, the inert gas is argon gas with a purity of 99.99%.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts a double austenitization combined with an austempering process on the basis of additive manufacturing of wear-resistant martensitic stainless steel additive parts, and realizes the strengthening and toughening treatment of high wear-resistant martensitic stainless steel. In the treatment method of the present invention, since the homogenization annealing process in the first stage is combined with the secondary annealing in the second stage for austenitization, the damage of the network eutectoid carbide to the mechanical properties of the additive parts can be reduced, which is conducive to the reduction of residual stress and the embrittlement of the wear-resistant martensitic stainless steel. The austempering process in the third stage can minimize the adverse effects of the martensitic lath structure on the mechanical properties of the additive parts. At the same time, during the implementation of the heat treatment process, the interaction between the nanophase precipitated in the matrix of the additive part organization and the dislocation also plays a certain role in improving the strength and microhardness of the additive part. The process flow of the present invention is simple, the cycle is short, and the treatment method is easy to control, which realizes the strengthening and toughening treatment of the wear-resistant martensitic stainless steel additive parts, and provides a new method for the strengthening and toughening treatment of alloy materials containing grain boundary network carbides and martensitic structures. The method of the present invention is applicable to, but not limited to, wear-resistant martensitic stainless steel prepared by various additive manufacturing methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The microhardness distribution results of the wear-resistant stainless steel additive component samples along the deposition direction before and after heat treatment in Example 1 of the present invention; Figure 2 The tensile properties of the wear-resistant stainless steel additive component samples before and after heat treatment in Example 1 of the present invention are shown; Figure 3 The microhardness distribution results of the wear-resistant stainless steel additive component samples along the deposition direction before and after heat treatment in Comparative Example 1 of the present invention; Figure 4 The tensile properties of the wear-resistant stainless steel additive parts before and after heat treatment in Comparative Example 1 of the present invention are shown; Figure 5 The microhardness distribution results of the wear-resistant stainless steel additive component samples along the deposition direction before and after heat treatment in Example 2 of the present invention; Figure 6 The tensile properties of the wear-resistant stainless steel additive component samples before and after heat treatment in Example 2 of the present invention are shown; Figure 7 TEM images of nano-precipitated phases and dislocation morphologies in the tissue matrix of the wear-resistant stainless steel additive parts samples prepared in Examples 1-8 of the present invention. DETAILED DESCRIPTION

[0016] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly and comprehensively understood.

[0017] On the basis of additive preparation of wear-resistant martensitic stainless steel alloy blocks, the wear-resistant martensitic stainless steel additive parts are strengthened and toughened by formulating heat treatment processes, which has important guiding significance for the further promotion and application of martensitic stainless steel additive parts.

[0018] The present invention provides a method for strengthening and toughening a wear-resistant martensitic stainless steel additive part. Different from the traditional method for strengthening and toughening a wear-resistant martensitic stainless steel additive part, the present invention adopts an additive part prepared by martensitic steel powder prepared in patent ZL201911024959.8, and adopts a double annealing combined with an isothermal quenching process for wear-resistant stainless steel additive parts containing grain boundary network carbides and martensitic structures, thereby realizing strengthening and toughening treatment of the wear-resistant martensitic stainless steel additive part, which specifically includes the following steps: S1. A 1 mm thick layer was removed from the upper surface of the additive part by wire cutting, and then tensile specimens and metallographic specimens were sampled. A 20 mm × 10 mm × 3 mm metallographic specimen was cut out along the deposition direction to obtain a wear-resistant martensitic stainless steel additive part sample.

[0019] S2. Clean the crucible hearth of the heat treatment furnace, and use acetone and alcohol to clean the wear-resistant martensitic stainless steel sample to be heat treated in turn.

[0020] S3. Place the cleaned wear-resistant martensitic stainless steel sample into the crucible furnace and seal the furnace. Evacuate the crucible furnace of the heat treatment furnace and fill it with inert gas. Repeat this process 2-4 times, then evacuate and fill it with inert gas to ensure that the wear-resistant martensitic stainless steel sample is always in a pure inert gas (99.99% high-purity argon) atmosphere during heating, heat preservation and cooling.

[0021] S4. Heat the wear-resistant martensitic stainless steel sample to a temperature range of 1000-1280︒C for homogenization annealing, and then cool it to room temperature in the furnace. The homogenization annealing treatment heating rate is 10-30︒C / min, and the holding time is calculated as no more than 150 min / mm thickness.

[0022] S5. Heat the sample again to a temperature range of 800-1100︒C for secondary annealing to perform double austenitization, then cool it to 300-600︒C in the furnace, and perform isothermal quenching treatment in the temperature range of 300-600︒C. The holding time is calculated as no more than 300min / mm thickness. Take out the sample and air cool it to room temperature to obtain a stainless steel sample. Among them, the heating rate of the secondary annealing is 10-30︒C / min, and the holding time is calculated as no more than 150 min / mm thickness.

[0023] The present invention adopts the process of double austenitization combined with isothermal quenching to prepare a stainless steel sample with high strength, toughness and hardness.

[0024] S6. In order to detect the change of the overall microhardness of the additively manufactured parts, the microhardness distribution trend was characterized along the deposition direction on the surface of the intercepted metallographic sample, and the metallographic sample was observed by 50,000 times transmission electron microscope bright field image.

[0025] In the above step S6, in order to ensure that the nano-precipitated phase produced during the heat treatment process can be clearly observed, the YOZ surface of the metallographic sample is used as the cross section to be observed, and a mixed solution of 10 g of anhydrous copper sulfate, 50 mL of concentrated hydrochloric acid (mass concentration 37.5%) and 50 mL of distilled water is used as the etching reagent for the metallographic sample. The corroded sample is placed in a JEM-200CX transmission electron microscope (TEM) at an accelerating voltage of 200 kV for further resolution.

[0026] In order to ensure accurate observation of the microhardness change trend before and after sample treatment, the overall microhardness value along the deposition direction was characterized on the surface of the intercepted metallographic sample. During the microhardness test, the loading load was always kept at 300 gf, the holding time was 15 s, and the distance between the test hardness points was kept at 0.3 mm. In order to observe the changes in the tensile properties of the samples before and after treatment, the tensile properties of the additive parts before and after heat treatment were tested using a quasi-static uniaxial tensile testing machine INSTRON 1195 equipped with a 12.5 mm INSTRON extensometer, all at 0.5 mm min. −1 The specimen is stretched at a constant displacement speed.

[0027] The method of the present invention is applicable to, but not limited to, wear-resistant martensitic stainless steel prepared by various additive manufacturing methods.

[0028] The following are specific embodiments.

[0029] Example 1 S1. A 1 mm thick layer was removed from the upper surface of the additive part by wire cutting, and then tensile specimens and metallographic specimens were sampled. A 20 mm × 10 mm × 3 mm metallographic specimen was cut out along the deposition direction to obtain a wear-resistant martensitic stainless steel sample.

[0030] S2. Clean the crucible hearth of the heat treatment furnace, and use acetone and alcohol to clean the wear-resistant martensitic stainless steel sample to be heat treated in turn.

[0031] S3. Place the cleaned wear-resistant martensitic stainless steel sample into the crucible furnace and seal the furnace. Repeat the process of vacuuming and filling the crucible furnace of the heat treatment furnace 2-4 times, and then vacuuming and filling with argon to ensure that the sample is always in a high-purity argon (99.99%) atmosphere during the heating, insulation and cooling process.

[0032] S4. The sample obtained in step S3 is heated to 1140°C for homogenization annealing at a heating rate of 10°C / min and a holding time of 120 min, and then cooled to room temperature in the furnace.

[0033] S5. Heat the sample obtained in step S4 to 940︒C for secondary annealing again, with a heating rate of 10︒C / min and a holding time of 60 min, and then cool it to 420︒C in the furnace.

[0034] S6. Keep the sample obtained in step S5 at 420°C for 60 min. After the heat preservation, take out the sample and air-cool it to room temperature.

[0035] S7. To ensure accurate observation of the microhardness trend before and after sample treatment, the overall microhardness value along the deposition direction is characterized on the surface of the intercepted metallographic sample. During the microhardness test, the loading load is always kept at 300gf, the holding time is 15 s, and the distance between the test hardness points is kept at 0.3 mm. The tensile properties of the additive parts before and after heat treatment are tested using a quasi-static uniaxial tensile testing machine INSTRON 1195 equipped with a 12.5 mm INSTRON extensometer.

[0036] See also Figure 1 and Figure 2 It can be seen that before and after heat treatment, the microhardness of the additive part has been significantly improved as a whole, the tensile strength has been significantly improved (from 1463 MPa of the additive part to 1708 MPa), and the elongation has also been significantly improved (from 0.7% of the additive part to 3.8%).

[0037] Comparative Example 1 S1. A 1 mm thick layer was removed from the upper surface of the additive part by wire cutting, and then tensile specimens and metallographic specimens were sampled. A 20 mm × 10 mm × 3 mm metallographic specimen was cut out along the deposition direction to obtain a wear-resistant martensitic stainless steel sample.

[0038] S2. Clean the crucible hearth of the heat treatment furnace, and use acetone and alcohol to clean the wear-resistant martensitic stainless steel sample to be heat treated in turn.

[0039] S3. Place the cleaned wear-resistant martensitic stainless steel sample into the crucible furnace and seal the furnace. Repeat the process of vacuuming and filling the crucible furnace of the heat treatment furnace 2-4 times, and then vacuuming and filling with argon to ensure that the sample is always in a high-purity argon (99.99%) atmosphere during the heating, insulation and cooling process.

[0040] S4. The sample obtained in step S3 is heated to 1140°C for homogenization annealing at a heating rate of 10°C / min and a holding time of 120 min, and then cooled to room temperature in the furnace.

[0041] S5. The sample obtained in step S4 is heated to 940°C for secondary annealing at a heating rate of 10°C / min and a holding time of 60 min, and then cooled to room temperature in the furnace.

[0042] S6. Heat the sample obtained in step S5 to 420°C again for 60 min. After the insulation, take out the sample and air-cool it to room temperature.

[0043] S7. Characterize the overall microhardness value along the deposition direction on the surface of the cut metallographic sample. Use a quasi-static uniaxial tensile testing machine INSTRON 1195 equipped with a 12.5 mm INSTRON extensometer to test the tensile properties of the additive parts before and after heat treatment.

[0044] See also Figure 3 and Figure 4 It can be seen that before and after heat treatment, the microhardness of the additive part was slightly improved, but the tensile strength was reduced (from 1463 MPa of the additive part to 1268 MPa), and the elongation was almost not improved (from 0.7% of the additive part to 0.97%).

[0045] By comparing Example 1 with Comparative Example 1, it can be seen that, relative to the additive parts in the deposited state before heat treatment, the stainless steel additive parts prepared by the double austenitizing combined with austempering process have the performance characteristics of high strength and high hardness, while the mechanical properties of the stainless steel additive parts prepared by the double austenitizing combined with tempering process do not change much.

[0046] Example 2 S1. A 1 mm thick layer was removed from the upper surface of the additive part by wire cutting, and then tensile specimens and metallographic specimens were sampled. A 20 mm × 10 mm × 3 mm metallographic specimen was cut out along the deposition direction to obtain a wear-resistant martensitic stainless steel sample.

[0047] S2. Clean the crucible hearth of the heat treatment furnace, and use acetone and alcohol to clean the wear-resistant martensitic stainless steel sample to be heat treated in turn.

[0048] S3. Place the cleaned wear-resistant martensitic stainless steel sample into the crucible furnace and seal the furnace. Repeat the process of vacuuming and filling the crucible furnace of the heat treatment furnace 2-4 times, and then vacuuming and filling with argon to ensure that the sample is always in a high-purity argon (99.99%) atmosphere during the heating, insulation and cooling process.

[0049] S4. The sample obtained in step S3 is heated to a temperature range of 1050︒C for homogenization annealing treatment, with a heating rate of 10︒C / min and a holding time of 120 min, and then cooled to room temperature in the furnace.

[0050] S5. The sample obtained in step S4 is heated again to a temperature range of 940°C for secondary annealing, with a heating rate of 10°C / min and a holding time of 60 min, and then cooled to 420°C in the furnace.

[0051] S6. Keep the sample in a temperature range of 420︒C for 60 min. After the insulation, take out the sample and air-cool it to room temperature.

[0052] S7. Characterize the overall microhardness value along the deposition direction on the surface of the cut metallographic sample. Use a quasi-static uniaxial tensile testing machine INSTRON 1195 equipped with a 12.5 mm INSTRON extensometer to test the tensile properties of the additive parts before and after heat treatment.

[0053] See also Figure 5 and Figure 6 It can be seen that the microhardness of the additive part does not change significantly before and after heat treatment, the tensile strength is slightly improved (from 1463 MPa of the additive part to 1575 MPa), but the elongation is significantly improved (from 0.7% of the additive part to 4.0%).

[0054] Example 3 S1. A 1 mm thick layer was removed from the upper surface of the additive part by wire cutting, and then tensile specimens and metallographic specimens were sampled. A 20 mm × 10 mm × 3 mm metallographic specimen was cut out along the deposition direction to obtain a wear-resistant martensitic stainless steel sample.

[0055] S2. Clean the crucible hearth of the heat treatment furnace, and use acetone and alcohol to clean the wear-resistant martensitic stainless steel sample to be heat treated in turn.

[0056] S3. Place the cleaned wear-resistant martensitic stainless steel sample into the crucible furnace and seal the furnace. Repeat the process of vacuuming and filling the crucible furnace of the heat treatment furnace 2-4 times, and then vacuuming and filling with argon to ensure that the sample is always in a high-purity argon (99.99%) atmosphere during the heating, insulation and cooling process.

[0057] S4. The sample obtained in step S3 is heated to a temperature range of 1140°C for homogenization annealing treatment, with a heating rate of 10°C / min and a holding time of 120 min, and then cooled to room temperature in the furnace.

[0058] S5. The sample obtained in step S4 is heated again to a temperature range of 960°C for secondary annealing, with a heating rate of 10°C / min and a holding time of 60 min, and then cooled to 450°C in the furnace.

[0059] S6. Keep the sample obtained in step S5 in a temperature range of 450︒C for 60 min. After the heat preservation, take out the sample and air-cool it to room temperature.

[0060] Example 4 S1. A 1 mm thick layer was removed from the upper surface of the additive part by wire cutting, and then a 20 mm × 10 mm × 3 mm metallographic sample was cut out along the deposition direction to obtain a wear-resistant martensitic stainless steel sample.

[0061] S2. Clean the crucible hearth of the heat treatment furnace, and use acetone and alcohol to clean the wear-resistant martensitic stainless steel sample to be heat treated in turn.

[0062] S3. Place the cleaned wear-resistant martensitic stainless steel sample into the crucible furnace and seal the furnace. Repeat the process of vacuuming and filling the crucible furnace of the heat treatment furnace 2-4 times, and then vacuuming and filling with argon to ensure that the sample is always in a high-purity argon (99.99%) atmosphere during the heating, insulation and cooling process.

[0063] S4. The sample obtained in step S3 is heated to a temperature range of 1140°C for homogenization annealing treatment, with a heating rate of 10°C / min and a holding time of 120 min, and then cooled to room temperature in the furnace.

[0064] S5. The sample obtained in step S4 is heated again to a temperature range of 940°C for secondary annealing, with a heating rate of 10°C / min and a holding time of 60 min, and then cooled to 400°C in the furnace.

[0065] S6. Keep the sample obtained in step S5 in a temperature range of 400︒C for 60 min. After the heat preservation, take out the sample and air cool it to room temperature.

[0066] Example 5 S1. A 1 mm thick layer was removed from the upper surface of the additive part by wire cutting, and then a 20 mm × 10 mm × 3 mm metallographic sample was cut out along the deposition direction to obtain a wear-resistant martensitic stainless steel sample.

[0067] S2. Clean the crucible hearth of the heat treatment furnace, and use acetone and alcohol to clean the wear-resistant martensitic stainless steel sample to be heat treated in turn.

[0068] S3. Place the cleaned wear-resistant martensitic stainless steel sample into the crucible furnace and seal the furnace. Repeat the process of vacuuming and filling the crucible furnace of the heat treatment furnace 2-4 times, and then vacuuming and filling with argon to ensure that the sample is always in a high-purity argon (99.99%) atmosphere during the heating, insulation and cooling process.

[0069] S4. The sample obtained in step S3 is heated to a temperature range of 1000°C for homogenization annealing treatment, with a heating rate of 10°C / min and a holding time of 600 min, and then cooled to room temperature in the furnace.

[0070] S5. The sample obtained in step S4 is heated again to a temperature range of 800°C for secondary annealing, with a heating rate of 20°C / min and a holding time of 600 min, and then cooled to 400°C in the furnace.

[0071] S6. Keep the sample obtained in step S5 in a temperature range of 400︒C for 600 min. After the heat preservation, take out the sample and cool it to room temperature by air cooling.

[0072] Example 6 S1. A 1 mm thick layer was removed from the upper surface of the additive part by wire cutting, and then a 20 mm × 10 mm × 3 mm metallographic sample was cut out along the deposition direction to obtain a wear-resistant martensitic stainless steel sample.

[0073] S2. Clean the crucible hearth of the heat treatment furnace, and use acetone and alcohol to clean the wear-resistant martensitic stainless steel sample to be heat treated in turn.

[0074] S3. Place the cleaned wear-resistant martensitic stainless steel sample into the crucible furnace and seal the furnace. Repeat the process of vacuuming and filling the crucible furnace of the heat treatment furnace 2-4 times, and then vacuuming and filling with argon to ensure that the sample is always in a high-purity argon (99.99%) atmosphere during the heating, insulation and cooling process.

[0075] S4. The sample obtained in step S3 is heated to a temperature range of 1100°C for homogenization annealing treatment, with a heating rate of 30°C / min and a holding time of 350 min, and then cooled to room temperature in the furnace.

[0076] S5. The sample obtained in step S4 is heated again to a temperature range of 1100°C for secondary annealing, with a heating rate of 10°C / min and a holding time of 30 min, and then cooled to 500°C in the furnace.

[0077] S6. Keep the sample obtained in step S5 in a temperature range of 500︒C for 30 min. After the heat preservation, take out the sample and air cool it to room temperature.

[0078] Example 7 S1. A 1 mm thick layer was removed from the upper surface of the additive part by wire cutting, and then a 20 mm × 10 mm × 3 mm metallographic sample was cut out along the deposition direction to obtain a wear-resistant martensitic stainless steel sample.

[0079] S2. Clean the crucible hearth of the heat treatment furnace, and use acetone and alcohol to clean the wear-resistant martensitic stainless steel sample to be heat treated in turn.

[0080] S3. Place the cleaned wear-resistant martensitic stainless steel sample into the crucible furnace and seal the furnace. Repeat the process of vacuuming and filling the crucible furnace of the heat treatment furnace 2-4 times, and then vacuuming and filling with argon to ensure that the sample is always in a high-purity argon (99.99%) atmosphere during the heating, insulation and cooling process.

[0081] S4. The sample obtained in step S3 is heated to a temperature range of 1200°C for homogenization annealing treatment, with a heating rate of 15°C / min and a holding time of 60 min, and then cooled to room temperature in the furnace.

[0082] S5. The sample obtained in step S4 is heated again to a temperature range of 900°C for secondary annealing, with a heating rate of 30°C / min and a holding time of 450 min, and then cooled to 300°C in the furnace.

[0083] S6. Keep the sample obtained in step S5 in a temperature range of 300°C for 300 min. After the heat preservation, take out the sample and cool it to room temperature through air cooling.

[0084] Example 8 S1. A 1 mm thick layer was removed from the upper surface of the additive part by wire cutting, and then a 20 mm × 10 mm × 3 mm metallographic sample was cut out along the deposition direction to obtain a wear-resistant martensitic stainless steel sample.

[0085] S2. Clean the crucible hearth of the heat treatment furnace, and use acetone and alcohol to clean the wear-resistant martensitic stainless steel sample to be heat treated in turn.

[0086] S3. Place the cleaned wear-resistant martensitic stainless steel sample into the crucible furnace and seal the furnace. Repeat the process of vacuuming and filling the crucible furnace of the heat treatment furnace 2-4 times, and then vacuuming and filling with argon to ensure that the sample is always in a high-purity argon (99.99%) atmosphere during the heating, insulation and cooling process.

[0087] S4. The sample obtained in step S3 is heated to a temperature range of 1280°C for homogenization annealing treatment, with a heating rate of 20°C / min and a holding time of 200 min, and then cooled to room temperature in the furnace.

[0088] S5. The sample obtained in step S4 is heated again to a temperature range of 1050︒C for secondary annealing, with a heating rate of 25︒C / min and a holding time of 250 min, and then cooled to 600︒C in the furnace.

[0089] S6. Keep the sample obtained in step S5 in a temperature range of 600︒C for 450 min. After the heat preservation, take out the sample and cool it to room temperature by air cooling.

[0090] See also Figure 7 This is the TEM bright field image result of the nano-precipitation phase and dislocation morphology in the heat-treated sample. Before the start of uniaxial stretching, the dislocations in the grains have not yet started. As the uniaxial stretching progresses, the dislocation density in the grains increases, and the nanoparticles will hinder the movement of some dislocations, causing dislocation entanglement and increasing the strength of the metal.

[0091] Based on the brittleness problem of wear-resistant martensitic stainless steel additive parts, the present invention adopts a heat treatment process of double austenitization combined with austempering to achieve the strengthening and toughening of stainless steel additive parts while also improving the tensile strength and microhardness. The tensile strength is 1575-1708 MPa, and the elongation is 3.8%-4.0%. It can be extended to but not limited to wear-resistant martensitic stainless steel additive parts prepared by various additive manufacturing methods.

[0092] This embodiment is only used to illustrate the method of the present invention, and does not limit the objects and parameter ranges involved in the method. Other modifications or equivalent substitutions made to the present invention by those skilled in the art should be included in the scope of the patent claims of the present invention as long as they do not depart from the spirit and scope of the present invention.

Claims

1. A method for strengthening and toughening a wear-resistant martensitic stainless steel additive component, characterized in that: The following steps are involved: The wear-resistant martensitic stainless steel sample was homogenized and annealed under inert gas, then subjected to secondary annealing, and finally to isothermal quenching to obtain a toughened wear-resistant stainless steel additive part.

2. The method for strengthening and toughening a wear-resistant martensitic stainless steel additive component according to claim 1, characterized in that: The temperature of homogenization annealing treatment is 1000-1280︒C, and the holding time is calculated as no more than 150 min / mm thickness.

3. The method for strengthening and toughening a wear-resistant martensitic stainless steel additive component according to claim 2, characterized in that: Increase the temperature to 1000-1280︒C at a rate of 10-30︒C / min.

4. The method for strengthening and toughening a wear-resistant martensitic stainless steel additive component according to claim 1, characterized in that: The wear-resistant martensitic stainless steel sample was homogenized and annealed under inert gas, cooled to room temperature in a furnace, and then subjected to secondary annealing.

5. The method for strengthening and toughening a wear-resistant martensitic stainless steel additive component according to claim 1, characterized in that: The temperature of secondary annealing is 800-1100︒C, and the holding time is calculated as no more than 150 min / mm thickness.

6. The method for strengthening and toughening a wear-resistant martensitic stainless steel additive component according to claim 5, characterized in that: The temperature was raised to 800-1100︒C at a heating rate of 10-30︒C / min.

7. The method for strengthening and toughening a wear-resistant martensitic stainless steel additive component according to claim 1, characterized in that: After the secondary annealing, the furnace is cooled to the isothermal quenching temperature for isothermal quenching.

8. The method for strengthening and toughening a wear-resistant martensitic stainless steel additive component according to claim 1, characterized in that: The temperature of isothermal quenching is 300-600︒C, and the holding time is calculated as no more than 300 min / mm thickness.

9. The method for strengthening and toughening a wear-resistant martensitic stainless steel additive component according to claim 1, characterized in that: After isothermal quenching, cool to room temperature in air.

10. The method for strengthening and toughening a wear-resistant martensitic stainless steel additive component according to claim 1, characterized in that: The inert gas is argon gas with a purity of 99.99%.

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