High-strength stainless steel seamless steel pipe and processing technology thereof

Abstract

The invention discloses a high-strength stainless steel seamless steel pipe and a machining process thereof, and relates to the technical field of alloy treatment. The processing technology of the high-strength stainless steel seamless steel tube comprises the following steps: step 1, pretreating the stainless steel seamless steel tube to obtain a pretreated stainless steel seamless steel tube; 2, an ion nitriding process is adopted for conducting synchronous nitriding treatment on the inner pipe and the outer pipe of the pretreated stainless steel seamless steel pipe, and the nitrided stainless steel seamless steel pipe is obtained; and 3, the plasma spraying technology is adopted, the surfaces of the inner pipe and the outer pipe of the nitrided stainless steel seamless steel pipe are each coated with a compression-resistant protective layer, and the high-strength stainless steel seamless steel pipe is obtained through microwave treatment. Pretreatment, plasma nitriding treatment and plasma spraying treatment are sequentially conducted on the inner pipe and the outer pipe of the stainless steel seamless steel pipe with the specific component proportion, the compressive strength, the fatigue resistance and other performance of the inner pipe and the outer pipe of the stainless steel seamless steel pipe are synergistically enhanced, and the quality of the stainless steel seamless steel pipe is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy processing, in particular to a high-strength stainless steel seamless pipe and a processing technology thereof. Background Art

[0002] Stainless steel seamless pipes are irreplaceable in high-end fields such as deep-sea oil and gas development, petrochemicals, aerospace, etc. due to their excellent corrosion resistance, high strength and long life. However, with the development of industrial equipment towards high parameters, traditional stainless steel pipes are gradually unable to meet the demand in terms of compressive strength (especially resistance to alternating internal and external pressure loads), fatigue resistance and surface wear resistance. Existing technologies mainly improve performance by optimizing material composition (such as increasing Cr and Ni content) or single surface treatment (such as nitriding and plating), but this method makes it difficult to achieve synergistic enhancement of the surface performance of the inner and outer tubes of stainless steel pipes.

[0003] Based on this, the present invention will provide a high-strength stainless steel seamless pipe and its processing technology, which is of great significance. Summary of the Invention

[0004] The object of the present invention is to provide a high-strength stainless steel seamless pipe and a processing technology thereof to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A processing technology for high-strength stainless steel seamless pipe comprises the following steps:

[0007] Step 1: pre-treating the stainless steel seamless pipe to obtain a pre-treated stainless steel seamless pipe;

[0008] Step 2: Using ion nitriding process, the inner and outer tubes of the pretreated stainless steel seamless pipe are subjected to synchronous nitriding treatment to obtain a nitrided stainless steel seamless pipe;

[0009] Step 3: Use plasma spraying process to coat a pressure-resistant protective layer on the inner and outer surfaces of the nitrided stainless steel seamless pipe, and then microwave treat it to obtain a high-strength stainless steel seamless pipe.

[0010] Furthermore, the composition of the stainless steel seamless pipe, by mass percentage, includes: C 0.05wt%, Si 0.80wt%, Mn 1.50wt%, Cr 17.5wt%, Ni 9.50wt%, V 0.065%, Mo 0.014wt%, Ti 0.013wt%, La 0.08%, and the balance is Fe.

[0011] Furthermore, the pretreatment includes two steps of cleaning and shot blasting; wherein, the cleaning process is as follows: (1) placing the stainless steel seamless pipe in a 5wt% sodium hydroxide aqueous solution, soaking and degreasing it at 80-100°C for 5-15 minutes, taking it out, cleaning it with clean water, and drying it; (2) placing it in a 5wt% hydrochloric acid aqueous solution, pickling it for 5-15 minutes, taking it out, brushing the inner and outer tube surfaces with a wire brush, and finally cleaning it with clean water, vacuum drying, and completing the cleaning process; the shot blasting process is as follows: using shot blasting equipment to shot blast the inner and outer tube surfaces of the cleaned stainless steel seamless pipe to obtain a pretreated stainless steel seamless pipe.

[0012] Furthermore, the parameters of the shot peening treatment are: working pressure of 1.0-1.5 MPa; spray gun feed speed of 30-70 cm / min; shot peening flow rate of 10-20 kg / min; and shot peening is 304 stainless steel shot with a diameter of 0.1-0.2 mm.

[0013] Furthermore, the roughness of the pretreated stainless steel seamless pipe is Ra=1.5-3 μm.

[0014] Furthermore, the parameters of the ion nitriding process are: a flow ratio of nitrogen to hydrogen of 1:(4-6); a nitriding temperature of 450-500° C.; a nitriding gas pressure of 50-200 Pa; a nitriding voltage of 650-750 V; and a nitriding time of 1-6 h.

[0015] Furthermore, the spray material used for the plasma spraying comprises the following raw materials in the following mass percentage ratios: Y 0.8-1.2%, graphene / Ti nanomaterial 1-2%, and the rest TiN.

[0016] Furthermore, the preparation method of the graphene / Ti nanomaterial is: adding graphene and Ti in a mass ratio of 1:20 into a ball mill, ball milling for 4 to 6 hours, and then vacuum sintering for 1 to 2 hours at 1000 to 1200° C. and 18 to 25 MPa to obtain the graphene / Ti nanomaterial.

[0017] Furthermore, the parameters of the plasma spraying process are: argon flow rate of 30-50 L / min; hydrogen flow rate of 15-25 L / min; power of 60-80 kW; powder feeding rate of 15-20 g / min; powder feeding pressure of 1.5-3 MPa; and spraying distance of 80-100 mm.

[0018] Furthermore, the thickness of the compression protection layer is 50-100 μm.

[0019] Furthermore, the parameters of the microwave treatment are: power of 200-400W; time of 1-2h.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention adopts a stainless steel seamless steel pipe with a specific composition ratio for subsequent nitriding strengthening. The stainless steel seamless steel pipe prepared under this composition has excellent compressive strength. Furthermore, the core mechanism of nitriding is that N diffuses inside the stainless steel, and then forms a nitride phase with the alloying elements of the stainless steel, thereby achieving the improvement of the performance of the stainless steel. The alloying elements in stainless steel that can form nitrides with N are mainly: Cr, V, Mo, and Ti. Therefore, the present invention limits the composition of the stainless steel seamless steel pipe and introduces a suitable proportion of Cr, V, Mo, and Ti to maximize the formation of nitrides between the alloying elements inside the stainless steel seamless steel pipe and N; at the same time, an appropriate amount of Si, Mn, Ni, and La is added. On the one hand, it can assist in the formation of nitrides, and on the other hand, it can escort the nitriding strengthening process of the stainless steel seamless steel pipe, improve the bonding strength of the nitride layer, and avoid the risk of brittle fracture of the nitride layer.

[0022] 2. In the present invention, the inner and outer tube surfaces of the stainless steel seamless pipe are first subjected to a cleaning treatment for degreasing and removing oxide films, and then the inner and outer tube surfaces are shot peened to obtain a pretreated stainless steel seamless pipe. The cleaning treatment can remove oil stains and oxide films, and has a positive effect on nitriding. On the one hand, shot peening can form a residual compressive stress layer on the inner and outer tube surfaces of the stainless steel seamless pipe, which has the effect of inhibiting crack growth and improving the compressive strength of the stainless steel seamless pipe; on the other hand, shot peening can refine the grains on the inner and outer tube surface areas of the stainless steel seamless pipe, which also plays a positive role in nitriding. In addition, after shot peening, the roughness of the pretreated stainless steel seamless pipe should not be too small or too large. Too small will increase the difficulty of nitriding; too large will make nitriding uneven, and serious microcracks will occur.

[0023] 3. The present invention adopts an ion nitriding process to perform simultaneous nitriding treatment on the inner and outer tubes of the pretreated stainless steel seamless pipe. Both the outer and inner surfaces of the stainless steel pipe are nitrided to obtain a nitrided layer of uniform quality, stable and excellent quality. The nitrided layer contains nitrides such as CrN, Cr2N, MoN, Mo2N, VN, TiN, etc., which can work together to greatly improve the compressive strength and fatigue resistance of the stainless steel pipe.

[0024] 4. Even if the inner and outer tubes of the stainless steel seamless pipe are nitrided simultaneously, the nitriding rate of the inner tube will be slightly lower than that of the outer tube. Therefore, with the increase of nitriding time, the nitriding strengthening effect of the outer surface of the tube will be better than that of the inner surface of the tube. However, the compressive strength of the stainless steel seamless pipe obtained by actual processing is not the same inside and outside the pipe. The compressive strength of the inner tube will be greater than that of the outer tube. If the difference in compressive strength between the inside and outside of the pipe is too large, in actual application, this will cause stress concentration in the stainless steel seamless pipe, thereby causing rupture, and there is a certain quality risk. Therefore, by simultaneously nitriding the inner and outer tubes of the stainless steel seamless pipe, the compressive strength of the inner and outer tubes can be balanced, thereby improving the quality of the stainless steel seamless pipe.

[0025] 5. In the present invention, a compressive protective layer is applied to the inner and outer surfaces of a nitrided stainless steel seamless pipe using plasma spraying technology, followed by microwave treatment to produce a high-strength stainless steel seamless pipe. The compressive protective layer is primarily composed of TiN, with the addition of rare earth metal Y enhancing grain boundary strengthening. The graphene / Ti nanomaterial enhances the compressive strength of the compressive protective layer through a three-dimensional network structure. Furthermore, microwave treatment partially eliminates residual stress in the compressive protective layer, improving its compactness and bonding to the stainless steel seamless pipe.

[0026] In summary, the present invention synergistically enhances the compressive strength and fatigue resistance of the inner and outer tubes of a stainless steel seamless pipe with a specific composition ratio by pre-treating them (cleaning and shot blasting), plasma nitriding, and plasma spraying, thereby improving the quality of the pipe. The optimized high-strength stainless steel seamless pipe boasts significantly higher internal and external compressive strength than the original, offering broader application prospects in fields such as deep-sea transportation, high-pressure boiler systems, petrochemical equipment, and aerospace. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] It should be noted that the following parts are calculated by weight, and the purchasers of all raw materials involved in the present invention include, without any special restrictions, the following examples:

[0029] In the following examples, graphene was in the form of a single-layer sheet with a sheet diameter of 0.2 to 2 μm and was purchased from Shanghai Lianghan Nanotechnology Development Co., Ltd.

[0030] TiN with a purity of 99.99% and an average particle size of 20 nm was purchased from Shanghai Buwei Applied Materials Technology Co., Ltd.

[0031] Ti with a purity of 99.99% and an average particle size of 20 nm was purchased from Shanghai Jiangge Chemical Co., Ltd.

[0032] The composition of the stainless steel seamless pipe, calculated by mass percentage, includes: C 0.05wt%, Si 0.80wt%, Mn 1.50wt%, Cr 17.5wt%, Ni 9.50wt%, V 0.065wt%, Mo 0.014wt%, Ti 0.013wt%, La 0.08%, and the balance is Fe; its outer diameter is 101.6mm and the wall thickness is 2mm.

[0033] Preliminary preparation: Preparation of graphene / Ti nanomaterials: Graphene and Ti were added into a ball mill at a mass ratio of 1:20, ball milled for 5 h, and then vacuum sintered at 1100°C and 20 MPa for 1.5 h to obtain graphene / Ti nanomaterials.

[0034] Example 1: A processing technology for high-strength stainless steel seamless pipe:

[0035] Step 1: pre-treating the stainless steel seamless pipe to obtain a pre-treated stainless steel seamless pipe;

[0036] 1. Cleaning: (1) Place the stainless steel seamless pipe in a 5wt% sodium hydroxide aqueous solution, soak and degrease at 90°C for 10 minutes, remove it, rinse it with clean water, and dry it at 100°C; (2) Place it in a 5wt% hydrochloric acid aqueous solution, pickle it for 10 minutes, remove it, brush the inner and outer surfaces of the pipe with a wire brush, and finally rinse it with clean water, and vacuum dry it at 100°C to complete the cleaning process;

[0037] The composition of the stainless steel seamless pipe, calculated by mass percentage, includes: C 0.05wt%, Si 0.80wt%, Mn 1.50wt%, Cr 17.5wt%, Ni 9.50wt%, V 0.065%, Mo 0.014wt%, Ti 0.013wt%, La 0.08%, and the balance is Fe;

[0038] 2. Shot peening: Shot peening equipment is used to shot peen the inner and outer surfaces of the cleaned stainless steel seamless pipe to obtain a pretreated stainless steel seamless pipe with Ra = 2.5 μm.

[0039] The parameters of the shot peening treatment are as follows: working pressure of 1.2 MPa; feed speed of the spray gun of 50 cm / min; shot flow rate of 15 kg / min; shot peening is 304 stainless steel shot with a diameter of 0.15 mm;

[0040] Step 2: Using ion nitriding process, the inner and outer tubes of the pretreated stainless steel seamless pipe are subjected to synchronous nitriding treatment to obtain a nitrided stainless steel seamless pipe;

[0041] The parameters of the ion nitriding process are: nitrogen and hydrogen flow ratio of 1:5; nitriding temperature of 480°C; nitriding pressure of 120Pa; nitriding voltage of 700V; nitriding time of 4h;

[0042] Step 3: A 50 μm thick compressive protective layer is coated on the inner and outer surfaces of the nitrided stainless steel seamless pipe using a plasma spraying process, and then microwave-treated to obtain a high-strength stainless steel seamless pipe.

[0043] The spray coating used in the plasma spraying comprises the following raw materials in the following mass percentage ratios: Y 1%, graphene / Ti nanomaterial 1.5%, and the remainder TiN;

[0044] The parameters of the plasma spraying process are: argon flow rate of 40 L / min; hydrogen flow rate of 20 L / min; power of 70 kW; powder feeding rate of 18 g / min; powder feeding pressure of 2 MPa; spraying distance of 90 mm;

[0045] The parameters of the microwave treatment are: power of 300 W and time of 1.5 h.

[0046] Example 2: A processing technology for high-strength stainless steel seamless pipe:

[0047] Step 1: pre-treating the stainless steel seamless pipe to obtain a pre-treated stainless steel seamless pipe;

[0048] 1. Cleaning: (1) Place the stainless steel seamless pipe in a 5wt% sodium hydroxide aqueous solution, soak and degrease at 90°C for 5 minutes, remove it, rinse it with clean water, and dry it at 100°C; (2) Place it in a 5wt% hydrochloric acid aqueous solution, pickle it for 5 minutes, remove it, brush the inner and outer surfaces of the pipe with a wire brush, and finally rinse it with clean water, and vacuum dry it at 100°C to complete the cleaning process;

[0049] The composition of the stainless steel seamless pipe, calculated by mass percentage, includes: C 0.05wt%, Si 0.80wt%, Mn 1.50wt%, Cr 17.5wt%, Ni 9.50wt%, V 0.065%, Mo 0.014wt%, Ti 0.013wt%, La 0.08%, and the balance is Fe;

[0050] 2. Shot peening: Shot peening equipment is used to shot peen the inner and outer surfaces of the cleaned stainless steel seamless pipe to obtain a pretreated stainless steel seamless pipe with Ra = 1.5 μm.

[0051] The parameters of the shot peening treatment are as follows: working pressure of 1.2 MPa; feed speed of the spray gun of 50 cm / min; shot flow rate of 15 kg / min; shot peening is 304 stainless steel shot with a diameter of 0.15 mm;

[0052] Step 2: Using ion nitriding process, the inner and outer tubes of the pretreated stainless steel seamless pipe are subjected to synchronous nitriding treatment to obtain a nitrided stainless steel seamless pipe;

[0053] The parameters of the ion nitriding process are: the flow ratio of nitrogen and hydrogen is 1:6; the nitriding temperature is 450°C; the nitriding pressure is 50Pa; the nitriding voltage is 650V; and the nitriding time is 1h.

[0054] Step 3: A 50 μm thick compressive protective layer is coated on the inner and outer surfaces of the nitrided stainless steel seamless pipe using a plasma spraying process, and then microwave-treated to obtain a high-strength stainless steel seamless pipe.

[0055] The spray coating material used in the plasma spraying comprises the following raw materials in the following mass percentage ratios: Y 0.8%, graphene / Ti nanomaterial 1%, and the remainder TiN;

[0056] The parameters of the plasma spraying process are: argon flow rate of 30 L / min; hydrogen flow rate of 15 L / min; power of 60 kW; powder feeding rate of 15 g / min; powder feeding pressure of 1.5 MPa; spraying distance of 100 mm;

[0057] The parameters of the microwave treatment are: power of 200 W and time of 1 h.

[0058] Example 3: A processing technology for high-strength stainless steel seamless pipe:

[0059] Step 1: pre-treating the stainless steel seamless pipe to obtain a pre-treated stainless steel seamless pipe;

[0060] 1. Cleaning: (1) Place the stainless steel seamless pipe in a 5wt% sodium hydroxide aqueous solution, soak and degrease at 90°C for 15 minutes, remove it, rinse it with clean water, and dry it at 100°C; (2) Place it in a 5wt% hydrochloric acid aqueous solution, pickle it for 15 minutes, remove it, brush the inner and outer surfaces of the pipe with a wire brush, and finally rinse it with clean water, and vacuum dry it at 100°C to complete the cleaning process;

[0061] The composition of the stainless steel seamless pipe, calculated by mass percentage, includes: C 0.05wt%, Si 0.80wt%, Mn 1.50wt%, Cr 17.5wt%, Ni 9.50wt%, V 0.065%, Mo 0.014wt%, Ti 0.013wt%, La 0.08%, and the balance is Fe;

[0062] 2. Shot peening: Shot peening equipment is used to shot peen the inner and outer surfaces of the cleaned stainless steel seamless pipe to obtain a pretreated stainless steel seamless pipe with Ra = 3μm.

[0063] The parameters of the shot peening treatment are as follows: working pressure of 1.2 MPa; feed speed of the spray gun of 50 cm / min; shot flow rate of 15 kg / min; shot peening is 304 stainless steel shot with a diameter of 0.15 mm;

[0064] Step 2: Using ion nitriding process, the inner and outer tubes of the pretreated stainless steel seamless pipe are subjected to synchronous nitriding treatment to obtain a nitrided stainless steel seamless pipe;

[0065] The parameters of the ion nitriding process are: the flow ratio of nitrogen and hydrogen is 1:4; the nitriding temperature is 500°C; the nitriding pressure is 200 Pa; the nitriding voltage is 750V; and the nitriding time is 6 hours.

[0066] Step 3: A 50 μm thick compressive protective layer is coated on the inner and outer surfaces of the nitrided stainless steel seamless pipe using a plasma spraying process, and then microwave-treated to obtain a high-strength stainless steel seamless pipe.

[0067] The spray coating used in the plasma spraying comprises the following raw materials in the following mass percentage ratios: Y 1.2%, graphene / Ti nanomaterial 2%, and the remainder TiN;

[0068] The parameters of the plasma spraying process are: argon flow rate of 50 L / min; hydrogen flow rate of 25 L / min; power of 80 kW; powder feeding rate of 20 g / min; powder feeding pressure of 3 MPa; spraying distance of 80 mm;

[0069] The parameters of the microwave treatment are: power of 400 W and time of 2 h.

[0070] The following comparative experiments were conducted based on Example 1, and comparative examples 1 to 4 were set as follows:

[0071] Comparative Example 1: Comparative Example 1 is based on Example 1, with the following adjustments: no pretreatment is performed on the stainless steel seamless steel pipe, and other processes remain unchanged, specifically:

[0072] A processing technology for high-strength stainless steel seamless pipe:

[0073] Step 1: Use ion nitriding process to synchronously nitriding the inner and outer tubes of the stainless steel seamless pipe to obtain a nitrided stainless steel seamless pipe;

[0074] The composition of the stainless steel seamless pipe, calculated by mass percentage, includes: C 0.05wt%, Si 0.80wt%, Mn 1.50wt%, Cr 17.5wt%, Ni 9.50wt%, V 0.065%, Mo 0.014wt%, Ti 0.013wt%, La 0.08%, and the balance is Fe;

[0075] The parameters of the ion nitriding process are: nitrogen and hydrogen flow ratio of 1:5; nitriding temperature of 480°C; nitriding pressure of 120Pa; nitriding voltage of 700V; nitriding time of 4h;

[0076] Step 2: Using a plasma spraying process, a 50 μm thick compressive protective layer is plated on the inner and outer surfaces of the nitrided stainless steel seamless pipe, and then microwave-treated to obtain a high-strength stainless steel seamless pipe;

[0077] The spray coating used in the plasma spraying comprises the following raw materials in the following mass percentage ratios: Y 1%, graphene / Ti nanomaterial 1.5%, and the remainder TiN;

[0078] The parameters of the plasma spraying process are: argon flow rate of 40 L / min; hydrogen flow rate of 20 L / min; power of 70 kW; powder feeding rate of 18 g / min; powder feeding pressure of 2 MPa; spraying distance of 90 mm;

[0079] The parameters of the microwave treatment are: power of 300 W and time of 1.5 h.

[0080] Comparative Example 2: Comparative Example 2 is based on Example 1, with the following adjustments: ion nitriding treatment is not performed on the pretreated stainless steel seamless pipe, and other processes remain unchanged, specifically:

[0081] A processing technology for high-strength stainless steel seamless pipe:

[0082] Step 1: pre-treating the stainless steel seamless pipe to obtain a pre-treated stainless steel seamless pipe;

[0083] 1. Cleaning: (1) Place the stainless steel seamless pipe in a 5wt% sodium hydroxide aqueous solution, soak and degrease at 90°C for 10 minutes, remove it, rinse it with clean water, and dry it at 100°C; (2) Place it in a 5wt% hydrochloric acid aqueous solution, pickle it for 10 minutes, remove it, brush the inner and outer surfaces of the pipe with a wire brush, and finally rinse it with clean water, and vacuum dry it at 100°C to complete the cleaning process;

[0084] The composition of the stainless steel seamless pipe, calculated by mass percentage, includes: C 0.05wt%, Si 0.80wt%, Mn 1.50wt%, Cr 17.5wt%, Ni 9.50wt%, V 0.065%, Mo 0.014wt%, Ti 0.013wt%, La 0.08%, and the balance is Fe;

[0085] 2. Shot peening: Shot peening equipment is used to shot peen the inner and outer surfaces of the cleaned stainless steel seamless pipe to obtain a pretreated stainless steel seamless pipe with Ra = 2.5 μm.

[0086] The parameters of the shot peening treatment are as follows: working pressure of 1.2 MPa; feed speed of the spray gun of 50 cm / min; shot flow rate of 15 kg / min; shot peening is 304 stainless steel shot with a diameter of 0.15 mm;

[0087] Step 2: Using a plasma spraying process, a 50 μm thick compressive protective layer is plated on the inner and outer surfaces of the pretreated stainless steel seamless pipe, and then microwave treated to obtain a high-strength stainless steel seamless pipe;

[0088] The spray coating used in the plasma spraying comprises the following raw materials in the following mass percentage ratios: Y 1%, graphene / Ti nanomaterial 1.5%, and the remainder TiN;

[0089] The parameters of the plasma spraying process are: argon flow rate of 40 L / min; hydrogen flow rate of 20 L / min; power of 70 kW; powder feeding rate of 18 g / min; powder feeding pressure of 2 MPa; spraying distance of 90 mm;

[0090] The parameters of the microwave treatment are: power of 300 W and time of 1.5 h.

[0091] Comparative Example 3: Comparative Example 3 is based on Example 1, with the following adjustments: the nitrided stainless steel seamless pipe is not subjected to plasma spraying treatment, and other processes remain unchanged, specifically:

[0092] A processing technology for high-strength stainless steel seamless pipe:

[0093] Step 1: pre-treating the stainless steel seamless pipe to obtain a pre-treated stainless steel seamless pipe;

[0094] 1. Cleaning: (1) Place the stainless steel seamless pipe in a 5wt% sodium hydroxide aqueous solution, soak and degrease at 90°C for 10 minutes, remove it, rinse it with clean water, and dry it at 100°C; (2) Place it in a 5wt% hydrochloric acid aqueous solution, pickle it for 10 minutes, remove it, brush the inner and outer surfaces of the pipe with a wire brush, and finally rinse it with clean water, and vacuum dry it at 100°C to complete the cleaning process;

[0095] The composition of the stainless steel seamless pipe, calculated by mass percentage, includes: C 0.05wt%, Si 0.80wt%, Mn 1.50wt%, Cr 17.5wt%, Ni 9.50wt%, V 0.065%, Mo 0.014wt%, Ti 0.013wt%, La 0.08%, and the balance is Fe;

[0096] 2. Shot peening: Shot peening equipment is used to shot peen the inner and outer surfaces of the cleaned stainless steel seamless pipe to obtain a pretreated stainless steel seamless pipe with Ra = 2.5 μm.

[0097] The parameters of the shot peening treatment are as follows: working pressure of 1.2 MPa; feed speed of the spray gun of 50 cm / min; shot flow rate of 15 kg / min; shot peening is 304 stainless steel shot with a diameter of 0.15 mm;

[0098] Step 2: Using ion nitriding process, the inner and outer tubes of the pretreated stainless steel seamless pipe are synchronously nitrided to obtain a nitrided stainless steel seamless pipe (high-strength stainless steel seamless pipe);

[0099] The parameters of the ion nitriding process are: a flow ratio of nitrogen to hydrogen of 1:5; a nitriding temperature of 480° C.; a nitriding pressure of 120 Pa; a nitriding voltage of 700 V; and a nitriding time of 4 h.

[0100] Comparative Example 4: Comparative Example 4 is based on Example 1, with the following adjustments: only the outer tube surface of the stainless steel seamless pipe is treated accordingly, and other processes remain unchanged, specifically:

[0101] A processing technology for high-strength stainless steel seamless pipe:

[0102] Step 1: pre-treating the stainless steel seamless pipe to obtain a pre-treated stainless steel seamless pipe;

[0103] 1. Cleaning: (1) Place the stainless steel seamless pipe in a 5wt% sodium hydroxide aqueous solution, soak and degrease at 90°C for 10 minutes, remove it, rinse it with clean water, and dry it at 100°C; (2) Place it in a 5wt% hydrochloric acid aqueous solution, pickle it for 10 minutes, remove it, brush the outer surface of the pipe with a wire brush, and finally rinse it with clean water, and vacuum dry it at 100°C to complete the cleaning process;

[0104] The composition of the stainless steel seamless pipe, calculated by mass percentage, includes: C 0.05wt%, Si 0.80wt%, Mn 1.50wt%, Cr 17.5wt%, Ni 9.50wt%, V 0.065%, Mo 0.014wt%, Ti 0.013wt%, La 0.08%, and the balance is Fe;

[0105] 2. Shot peening: The outer surface of the cleaned stainless steel seamless pipe is shot peened using a shot peening device to obtain a pretreated stainless steel seamless pipe with Ra = 2.5 μm.

[0106] The parameters of the shot peening treatment are as follows: working pressure of 1.2 MPa; feed speed of the spray gun of 50 cm / min; shot flow rate of 15 kg / min; shot peening is 304 stainless steel shot with a diameter of 0.15 mm;

[0107] Step 2: Using ion nitriding process, nitriding the outer tube of the pretreated stainless steel seamless pipe to obtain a nitrided stainless steel seamless pipe;

[0108] The parameters of the ion nitriding process are: nitrogen and hydrogen flow ratio of 1:5; nitriding temperature of 480°C; nitriding pressure of 120Pa; nitriding voltage of 700V; nitriding time of 4h;

[0109] Step 3: A 50 μm thick compressive protective layer is plated on the outer surface of the nitrided stainless steel seamless pipe using a plasma spraying process, and then microwave-treated to obtain a high-strength stainless steel seamless pipe;

[0110] The spray coating used in the plasma spraying comprises the following raw materials in the following mass percentage ratios: Y 1%, graphene / Ti nanomaterial 1.5%, and the remainder TiN;

[0111] The parameters of the plasma spraying process are: argon flow rate of 40 L / min; hydrogen flow rate of 20 L / min; power of 70 kW; powder feeding rate of 18 g / min; powder feeding pressure of 2 MPa; spraying distance of 90 mm;

[0112] The parameters of the microwave treatment are: power of 300 W and time of 1.5 h.

[0113] Performance test: The high-strength stainless steel seamless pipes prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to compressive strength tests, and their external and internal pressure resistance were tested respectively. The specific test results are shown in Table 1 below:

[0114] Table 1

[0115]

[0116] Result analysis: From the data in Table 1 above, it can be seen that: by comprehensively comparing the embodiment and comparative examples 1 to 4 and the stainless steel seamless pipe, it can be seen that: the present invention performs pretreatment, plasma nitriding treatment, and plasma spraying treatment on the inner and outer pipes of the stainless steel seamless pipe with a specific composition ratio, and finally synergistically enhances the compressive strength of the inner and outer pipes of the stainless steel seamless pipe, and its internal pressure resistance and external pressure resistance are much higher than those of the original stainless steel seamless pipe; in addition, the compressive strength of the inner and outer pipes of the stainless steel seamless pipe also tends to be uniform, which can greatly guarantee the quality of the stainless steel seamless pipe.

[0117] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A processing technology for high-strength stainless steel seamless pipe, characterized by: The following steps are involved: Step 1: pre-treating the stainless steel seamless pipe to obtain a pre-treated stainless steel seamless pipe; Step 2: Using ion nitriding process, the inner and outer tubes of the pretreated stainless steel seamless pipe are subjected to synchronous nitriding treatment to obtain a nitrided stainless steel seamless pipe; Step 3: A plasma spraying process is used to coat a compressive protective layer on the inner and outer surfaces of the nitrided stainless steel seamless pipe, and then microwave treatment is performed to obtain a high-strength stainless steel seamless pipe; The composition of the stainless steel seamless pipe, by mass percentage, includes: C 0.05wt%, Si 0.80wt%, Mn 1.50wt%, Cr 17.5wt%, Ni 9.50wt%, V 0.065%, Mo 0.014wt%, Ti 0.013wt%, La 0.08%, and the balance is Fe.

2. The processing technology of a high-strength stainless steel seamless pipe according to claim 1, characterized in that: The pretreatment includes two steps of cleaning and shot blasting; The cleaning process is as follows: (1) placing the stainless steel seamless pipe in a 5wt% sodium hydroxide aqueous solution, soaking it at 80-100°C for degreasing for 5-15 minutes, taking it out, cleaning it with clean water, and drying it; (2) placing it in a 5wt% hydrochloric acid aqueous solution, pickling it for 5-15 minutes, taking it out, brushing the inner and outer surfaces of the pipe with a wire brush, and finally cleaning it with clean water, vacuum drying it, and completing the cleaning process; The shot peening process is as follows: using a shot peening device to shot peen the inner and outer surfaces of the cleaned stainless steel seamless pipe to obtain a pretreated stainless steel seamless pipe; The parameters of the shot peening treatment are as follows: working pressure of 1.0-1.5 MPa; feed speed of the spray gun of 30-70 cm / min; shot flow rate of 10-20 kg / min; and shot peening is 304 stainless steel shot with a diameter of 0.1-0.2 mm.

3. The processing technology of a high-strength stainless steel seamless pipe according to claim 1, characterized in that: The roughness of the pretreated stainless steel seamless pipe is Ra=1.5-3 μm.

4. The processing technology of a high-strength stainless steel seamless pipe according to claim 1, characterized in that: The parameters of the ion nitriding process are: a flow ratio of nitrogen to hydrogen of 1:(4-6); a nitriding temperature of 450-500° C.; a nitriding pressure of 50-200 Pa; a nitriding voltage of 650-750 V; and a nitriding time of 1-6 hours.

5. The processing technology of a high-strength stainless steel seamless pipe according to claim 1, characterized in that: The spray coating material used for plasma spraying comprises the following raw materials in the following mass percentage ratios: Y 0.8-1.2%, graphene / Ti nanomaterial 1-2%, and the rest TiN.

6. The processing technology of a high-strength stainless steel seamless pipe according to claim 5, characterized in that: The preparation method of the graphene / Ti nanomaterial comprises: adding graphene and Ti in a mass ratio of 1:20 into a ball mill, ball milling for 4-6 hours, and then vacuum sintering for 1-2 hours at 1000-1200° C. and 18-25 MPa to obtain the graphene / Ti nanomaterial.

7. The processing technology of a high-strength stainless steel seamless pipe according to claim 1, characterized in that: The parameters of the plasma spraying process are: argon flow rate of 30-50 L / min; hydrogen flow rate of 15-25 L / min; power of 60-80 kW; powder feeding rate of 15-20 g / min; powder feeding pressure of 1.5-3 MPa; and spraying distance of 80-100 mm.

8. The processing technology of a high-strength stainless steel seamless pipe according to claim 1, characterized in that: The thickness of the compression protection layer is 50-100 μm.

9. The processing technology of a high-strength stainless steel seamless pipe according to claim 1, characterized in that: The parameters of the microwave treatment are: power of 200-400W; time of 1-2h.

10. A high-strength stainless steel seamless pipe obtained by processing the high-strength stainless steel seamless pipe according to any one of claims 1 to 9.

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