Corrosion-resistant composite seamless steel tube and preparation process thereof

Abstract

The invention relates to a corrosion-resistant composite seamless steel pipe and a preparation process thereof, and belongs to the technical field of seamless steel pipes, the corrosion-resistant composite seamless steel pipe comprises an outer-layer base pipe and a lining pipe, the lining pipe is located on the inner side of the outer-layer base pipe, and the outer-layer base pipe comprises the following components in percentage by mass: 0.18-0.22% of C, 0.18-0.22% of B, 0.18-0.22% of C, and the balance of Fe and inevitable impurities; 0.2 to 0.3 percent of Si; 0.8% to 1.2% of Cr; mn: 0.2 to 0.4%; 0.18% to 0.22% of W; cu: 0.05 to 0.07%; less than or equal to 0.010% of P; s is less than or equal to 0.005%, and the balance is Fe; the lining pipe comprises the following components: 0.06 to 0.10 percent of C; 0.25 to 0.35 percent of Si; 16.0% to 20.0% of Cr; 7.5 to 8.5 percent of Ni; 0.12% to 0.18% of Al; 0.4 to 0.8 percent of Mn; ti: 0.05 to 0.15%; less than or equal to 0.010% of P; s is less than or equal to 0.005%, and the balance is Fe. The prepared corrosion-resistant composite seamless steel pipe is high in interface bonding strength, and the service life can be prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of seamless steel pipes, and in particular relates to a corrosion-resistant composite seamless steel pipe and a preparation process thereof. Background Art

[0002] Corrosion-resistant composite seamless steel pipe is a new type of composite pipe with corrosion resistance, which is composed of an outer base pipe and an inner liner pipe. Generally, the outer base pipe is the outer layer of the steel pipe, which has high mechanical strength and low price; the inner liner pipe is the inner layer of the steel pipe, which is thinner.

[0003] In order to ensure the anti-corrosion performance indicators, the outer base pipe and the inner liner pipe are usually combined so that the composite steel pipe can reduce the cost while combining the advantages of different metal materials to meet the performance requirements.

[0004] In the prior art, the interface bonding tightness of the inner and outer layers of the corrosion-resistant composite seamless steel pipe is poor, which leads to the inner and outer pipes being easily separated after long-term use, and ultimately the advantages of the inner and outer layer materials cannot be complemented, affecting subsequent use.

[0005] Metal tungsten is added during the preparation of seamless steel pipes to enhance the bonding strength between the outer base pipe and the inner liner pipe by using the anchor fixing effect of tungsten. However, during the quenching process, the workpiece cools quickly, which will cause the volume change of the material. Due to the different thicknesses of the pipes on both sides of the composite steel pipe interface, there will be a large difference in the volume change of the materials on both sides of the interface, causing the inner and outer pipes to slip relative to each other at the bonding surface, thereby gradually making the anchoring enhancement effect of tungsten fail and causing the interface bonding strength to decrease. Summary of the invention

[0006] 1. Technical issues to be solved

[0007] In view of the deficiencies in the prior art, the present invention provides a corrosion-resistant composite seamless steel pipe and a preparation process thereof.

[0008] (II) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0010] A corrosion-resistant composite seamless steel pipe comprises an outer base pipe and an inner liner pipe, wherein the inner liner pipe is located inside the outer base pipe, and the raw materials of the outer base pipe comprise the following components by mass percentage: C: 0.18-0.22%; Si: 0.2-0.3%; Cr: 0.8-1.2%; Mn: 0.2-0.4%; W: 0.18-0.22%; Cu: 0.05-0.07%; P≤0.010%; S≤0. 005%, the balance is Fe; the raw materials of the inner lining pipe include the following components in percentage by mass: C: 0.06-0.10%; Si: 0.25-0.35%; Cr: 16.0-20.0%; Ni: 7.5-8.5%; Al: 0.12-0.18%; Mn: 0.4-0.8%; Ti: 0.05-0.15%; P≤0.010%; S≤0.005%, the balance is Fe.

[0011] Furthermore, the raw material of the outer layer substrate tube includes the following components in percentage by mass: C: 0.2%; Si: 0.25%; Cr: 1.0%; Mn: 0.3%; W: 0.20%; Cu: 0.06%; P: 0.010%; S: 0.005%, and the balance is Fe.

[0012] Furthermore, the raw material of the inner lining pipe includes the following components in percentage by mass: C: 0.08%; Si: 0.30%; Cr: 18.0%; Ni: 8.0%; Al: 0.15%; Mn: 0.6%; Ti: 0.10%; P: 0.010%; S: 0.005%, and the balance is Fe.

[0013] A preparation process of a corrosion-resistant composite seamless steel pipe comprises the following steps:

[0014] S1: After mixing the raw materials of the outer layer base pipe, molten steel A is smelted through the process of converter + LF furnace refining + vacuum degassing; after mixing the raw materials of the inner liner pipe, molten steel B is smelted through the process of converter + LF furnace refining + vacuum degassing;

[0015] S2: Using the centrifugal casting method, the outer base pipe is cast using molten steel A, and after the outer base pipe is solidified, the inner liner pipe is cast inside the outer base pipe using molten steel B to form a composite pipe blank;

[0016] S3: rolling the composite tube blank in S2 to obtain a composite tube blank;

[0017] S4: cooling the composite pipe blank in S3 at a cooling rate of 80°C / min until the temperature reaches 450-550°C, then heating the cooled composite pipe blank to a temperature of 950-980°C and then keeping it warm. After keeping warm, the composite pipe blank is transported to a quenching system and quenched and cooled using a quenching liquid. The quenching is performed by internal spraying and external showering. The inner liner pipe is cooled by a quenching liquid, and the outer base pipe is cooled by water. After the quenching is completed, the steel pipe is transported to a tempering furnace for tempering to obtain a preliminary composite steel pipe. The tempering furnace temperature is 770-790°C.

[0018] S5: The preliminary composite steel pipe of S4 is taken out of the furnace and cooled to obtain a corrosion-resistant composite seamless steel pipe.

[0019] Furthermore, during the pouring process of S2, the centrifugal rotation speed is 8 to 12 r / s.

[0020] Furthermore, during the pouring process of S2, the thickness ratio between the inner lining pipe and the outer base pipe is 3:0.8-1.2.

[0021] Furthermore, during the S3 rolling process, the rolling speed is 6-8 m / min, the rotating speed of the rotary table is 180-240 r / min, the inlet temperature of the tube rolling mill is 1100-1140°C, and the outlet temperature is 910-930°C.

[0022] Furthermore, during the S4 heat treatment process, the insulation time during heating and insulation is controlled according to the wall thickness coefficient of 2 min / mm.

[0023] Furthermore, during the S4 heat treatment process, the tempering holding time during tempering is controlled according to the wall thickness coefficient of 3 min / mm.

[0024] Furthermore, the preparation of the quenching liquid includes the following steps:

[0025] Q1: Weigh 70 parts of paraffin-based white oil by weight, heat to 55-65° C., add 2-4 parts of sodium dioctyl sulfonate dibutyrate and 0.5-0.7 parts of alkylated diphenylamine, stir evenly, and obtain quenching preformed liquid A for standby use;

[0026] Q2: Weigh 25-35 parts of 100SN base oil by weight, add 1.2-1.8 parts of polyisobutylene succinate at room temperature, stir evenly, and obtain quenching prefabricated liquid B;

[0027] Q3: Under stirring conditions, the quenching pre-liquid B prepared in Q2 is added dropwise to the quenching pre-liquid A prepared in Q1, stirred for 20 to 40 minutes, and cooled to room temperature to obtain the quenching liquid.

[0028] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0029] 1. Since tungsten has a high melting point and is difficult to melt, when pouring the inner layer of molten steel, hard protrusions will form on the inner wall of the outer base tube. These protrusions will increase the surface roughness and the contact area, and will also form anchor points after the molten steel solidifies, thereby enhancing the bonding strength of the interface, and ultimately allowing the outer base tube and the inner liner tube to be tightly fused together.

[0030] 2. The present invention uses different quenching materials to quench the inner and outer surfaces of the composite pipe respectively. The inner lining pipe inside the composite steel pipe is cooled by quenching liquid, and the outer base pipe is cooled by water.

[0031] The quenching liquid contains polyisobutylene succinate, which can improve the diffusion capacity of the quenching liquid, so that the quenching liquid can cover the inner wall of the liner more evenly, and achieve uniform heat dispersion on the wall of the liner. In addition, the wall of the liner is thinner, and the quenching liquid can make the thinner pipe on the inside produce a matching volume change with the outer base pipe at the joint surface at a specific cooling rate, giving full play to the anchoring enhancement effect caused by the addition of tungsten in the preparation process of the corrosion-resistant seamless steel pipe, thereby ensuring the bonding tightness and interface bonding strength between the outer base pipe and the liner, and extending the service life of the composite steel pipe. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] A corrosion-resistant composite seamless steel pipe comprises an outer base pipe and an inner liner pipe, wherein the inner liner pipe is located inside the outer base pipe.

[0035] The raw materials of the outer layer base pipe include the following components in percentage by mass: C: 0.2%; Si: 0.25%; Cr: 1.0%; Mn: 0.3%; W: 0.20%; Cu: 0.06%; P: 0.010%; S: 0.005%, and the balance is Fe; the raw materials of the inner lining pipe include the following components in percentage by mass: C: 0.08%; Si: 0.30%; Cr: 18.0%; Ni: 8.0%; Al: 0.15%; Mn: 0.6%; Ti: 0.10%; P: 0.010%; S: 0.005%, and the balance is Fe.

[0036] A preparation process of a corrosion-resistant composite seamless steel pipe comprises the following steps:

[0037] S1: After mixing the raw materials of the outer layer base pipe, molten steel A is smelted through the process of converter + LF furnace refining + vacuum degassing; after mixing the raw materials of the inner liner pipe, molten steel B is smelted through the process of converter + LF furnace refining + vacuum degassing;

[0038] S2: Using the centrifugal casting method, the outer base pipe is cast using molten steel A, and after the outer base pipe is solidified, the inner liner pipe is cast inside the outer base pipe using molten steel B to form a composite pipe blank;

[0039] S3: rolling the composite tube blank in S2 to obtain a composite tube blank;

[0040] S4: cooling the composite tube blank in S3 at a cooling rate of 80°C / min until the temperature reaches 500°C, then heating the cooled composite tube blank to a temperature of 965°C and then keeping it warm, after keeping it warm, transporting the composite tube blank to a quenching system and using a quenching liquid for quenching and cooling, the quenching adopts an internal spraying and external showering method, the inner lining tube is cooled by a quenching liquid, and the outer base tube is cooled by water, after the quenching is completed, the steel pipe is transported to a tempering furnace for tempering to obtain a preliminary composite steel pipe, and the tempering furnace temperature is 780°C;

[0041] S5: The preliminary composite steel pipe of S4 is taken out of the furnace and cooled to obtain a corrosion-resistant composite seamless steel pipe.

[0042] During the S2 pouring process, the centrifugal rotation speed is 10r / s.

[0043] During the S2 pouring process, the thickness ratio between the inner lining pipe and the outer base pipe is 3:1.

[0044] During the S3 rolling process, the rolling speed is 7 m / min, the rotating speed of the rotary table is 180 r / min, the inlet temperature of the tube rolling mill is 1120° C., and the outlet temperature is 920° C.

[0045] During the S4 heat treatment process, the insulation time during heating and insulation is controlled according to the wall thickness coefficient of 2min / mm.

[0046] During the S4 heat treatment process, the tempering holding time during tempering is controlled according to the wall thickness coefficient of 3min / mm.

[0047] The preparation of the quenching liquid includes the following contents:

[0048] Q1: Weigh 70 parts of paraffin-based white oil by weight, heat to 60°C, add 3 parts of sodium dioctyl sulfonate dibutyrate and 0.6 parts of alkylated diphenylamine, stir evenly, and obtain quenching prefabricated liquid A for standby use;

[0049] Q2: Weigh 30 parts of 100SN base oil by weight, add 1.5 parts of polyisobutylene succinate at room temperature, stir evenly, and obtain quenching prefabricated liquid B;

[0050] Q3: Under stirring conditions, the quenching pre-liquid B prepared in Q2 is added dropwise to the quenching pre-liquid A prepared in Q1, stirred for 30 minutes, and cooled to room temperature to obtain the quenching liquid.

[0051] Example 2

[0052] A corrosion-resistant composite seamless steel pipe comprises an outer base pipe and an inner liner pipe, wherein the inner liner pipe is located inside the outer base pipe.

[0053] The raw materials of the outer layer base pipe include the following components in percentage by mass: C: 0.18%; Si: 0.2%; Cr: 0.8%; Mn: 0.2%; W: 0.18%; Cu: 0.05%; P: 0.010%; S: 0.005%, and the balance is Fe; the raw materials of the inner lining pipe include the following components in percentage by mass: C: 0.06%; Si: 0.25%; Cr: 16.0%; Ni: 7.5%; Al: 0.12%; Mn: 0.4%; Ti: 0.05%; P: 0.010%; S: 0.005%, and the balance is Fe.

[0054] A preparation process of a corrosion-resistant composite seamless steel pipe comprises the following steps:

[0055] S1: After mixing the raw materials of the outer layer base pipe, molten steel A is smelted through the process of converter + LF furnace refining + vacuum degassing; after mixing the raw materials of the inner liner pipe, molten steel B is smelted through the process of converter + LF furnace refining + vacuum degassing;

[0056] S2: Using the centrifugal casting method, the outer base pipe is cast using molten steel A, and after the outer base pipe is solidified, the inner liner pipe is cast inside the outer base pipe using molten steel B to form a composite pipe blank;

[0057] S3: rolling the composite tube blank in S2 to obtain a composite tube blank;

[0058] S4: cooling the composite pipe blank in S3 at a cooling rate of 80°C / min until the temperature reaches 450°C, then heating the cooled composite pipe blank to a temperature of 950°C and then keeping it warm. After keeping warm, the composite pipe blank is transported to a quenching system for quenching and cooling using a quenching liquid. The quenching is performed by internal spraying and external showering. The inner liner pipe is cooled by a quenching liquid, and the outer base pipe is cooled by water. After the quenching is completed, the steel pipe is transported to a tempering furnace for tempering to obtain a preliminary composite steel pipe. The tempering furnace temperature is 770°C.

[0059] S5: The preliminary composite steel pipe of S4 is taken out of the furnace and cooled to obtain a corrosion-resistant composite seamless steel pipe.

[0060] During the S2 pouring process, the centrifugal rotation speed is 8r / s.

[0061] During the S2 pouring process, the thickness ratio between the inner lining pipe and the outer base pipe is 3:0.8.

[0062] During the S3 rolling process, the rolling speed was 6 m / min, the rotating speed of the rotary table was 180 r / min, the inlet temperature of the tube rolling mill was 1100° C., and the outlet temperature was 910° C.

[0063] During the S4 heat treatment process, the insulation time during heating and insulation is controlled according to the wall thickness coefficient of 2min / mm.

[0064] During the S4 heat treatment process, the tempering holding time during tempering is controlled according to the wall thickness coefficient of 3min / mm.

[0065] The preparation of the quenching liquid includes the following contents:

[0066] Q1: Weigh 70 parts of paraffin-based white oil by weight, heat to 55°C, add 2 parts of sodium dioctyl sulfonate dibutyrate and 0.5 parts of alkylated diphenylamine, stir evenly, and obtain quenching prefabricated liquid A for standby use;

[0067] Q2: Weigh 25 parts of 100SN base oil by weight, add 1.2 parts of polyisobutylene succinate at room temperature, stir evenly, and obtain quenching prefabricated liquid B;

[0068] Q3: Under stirring conditions, the quenching pre-liquid B prepared in Q2 is added dropwise to the quenching pre-liquid A prepared in Q1, stirred for 20 minutes, and cooled to room temperature to obtain the quenching liquid.

[0069] Example 3

[0070] A corrosion-resistant composite seamless steel pipe comprises an outer base pipe and an inner liner pipe, wherein the inner liner pipe is located inside the outer base pipe.

[0071] The raw materials of the outer layer base pipe include the following components in percentage by mass: C: 0.22%; Si: 0.3%; Cr: 1.2%; Mn: 0.4%; W: 0.22%; Cu: 0.07%; P: 0.010%; S: 0.005%, and the balance is Fe; the raw materials of the inner lining pipe include the following components in percentage by mass: C: 0.10%; Si: 0.35%; Cr: 20.0%; Ni: 8.5%; Al: 0.18%; Mn: 0.8%; Ti: 0.15%; P: 0.010%; S: 0.005%, and the balance is Fe.

[0072] A preparation process of a corrosion-resistant composite seamless steel pipe comprises the following steps:

[0073] S1: After mixing the raw materials of the outer layer base pipe, molten steel A is smelted through the process of converter + LF furnace refining + vacuum degassing; after mixing the raw materials of the inner liner pipe, molten steel B is smelted through the process of converter + LF furnace refining + vacuum degassing;

[0074] S2: Using the centrifugal casting method, the outer base pipe is cast using molten steel A, and after the outer base pipe is solidified, the inner liner pipe is cast inside the outer base pipe using molten steel B to form a composite pipe blank;

[0075] S3: rolling the composite tube blank in S2 to obtain a composite tube blank;

[0076] S4: cooling the composite tube blank in S3 at a cooling rate of 80°C / min until the temperature reaches 550°C, then heating the cooled composite tube blank to a temperature of 980°C and then keeping it warm. After keeping warm, the composite tube blank is transported to a quenching system for quenching and cooling using a quenching liquid. The quenching is performed by internal spraying and external showering. The inner lining tube is cooled by a quenching liquid, and the outer base tube is cooled by water. After the quenching is completed, the steel tube is transported to a tempering furnace for tempering to obtain a preliminary composite steel tube. The tempering furnace temperature is 790°C.

[0077] S5: The preliminary composite steel pipe of S4 is taken out of the furnace and cooled to obtain a corrosion-resistant composite seamless steel pipe.

[0078] During the S2 pouring process, the centrifugal rotation speed is 12r / s.

[0079] During the S2 pouring process, the thickness ratio between the inner lining pipe and the outer base pipe is 3:1.2.

[0080] During the S3 rolling process, the rolling speed was 8 m / min, the rotating speed of the rotary table was 240 r / min, the inlet temperature of the tube rolling mill was 1140° C., and the outlet temperature was 930° C.

[0081] During the S4 heat treatment process, the insulation time during heating and insulation is controlled according to the wall thickness coefficient of 2min / mm.

[0082] During the S4 heat treatment process, the tempering holding time during tempering is controlled according to the wall thickness coefficient of 3min / mm.

[0083] The preparation of the quenching liquid includes the following contents:

[0084] Q1: Weigh 70 parts of paraffin-based white oil by weight, heat to 65°C, add 4 parts of sodium dioctyl dibutyrate sulfonate and 0.7 parts of alkylated diphenylamine, stir evenly, and obtain quenching prefabricated liquid A for standby use;

[0085] Q2: Weigh 35 parts of 100SN base oil by weight, add 1.8 parts of polyisobutylene succinate at room temperature, stir evenly, and obtain quenching prefabricated liquid B;

[0086] Q3: Under stirring conditions, the quenching pre-liquid B prepared in Q2 is added dropwise to the quenching pre-liquid A prepared in Q1, stirred for 40 minutes, and cooled to room temperature to obtain the quenching liquid.

[0087] Example 4

[0088] A corrosion-resistant composite seamless steel pipe comprises an outer base pipe and an inner lining pipe, wherein the inner lining pipe is located on the inner side of the outer base pipe. The raw materials of the outer base pipe comprise the following components by mass percentage: C: 0.19%; Si: 0.23%; Cr: 0.9%; Mn: 0.25%; W: 0.19%; Cu: 0.055%; P: 0.010%; S: 0.005%, and the balance is Fe; the raw materials of the inner lining pipe comprise the following components by mass percentage: C: 0.07%; Si: 0.28%; Cr: 17.0%; Ni: 7.8%; Al: 0.13%; Mn: 0.5%; Ti: 0.08%; P: 0.010%; S: 0.005%, and the balance is Fe.

[0089] A preparation process of a corrosion-resistant composite seamless steel pipe comprises the following steps:

[0090] S1: After mixing the raw materials of the outer layer base pipe, molten steel A is smelted through the process of converter + LF furnace refining + vacuum degassing; after mixing the raw materials of the inner liner pipe, molten steel B is smelted through the process of converter + LF furnace refining + vacuum degassing;

[0091] S2: Using the centrifugal casting method, the outer base pipe is cast using molten steel A, and after the outer base pipe is solidified, the inner liner pipe is cast inside the outer base pipe using molten steel B to form a composite pipe blank;

[0092] S3: rolling the composite tube blank in S2 to obtain a composite tube blank;

[0093] S4: cooling the composite pipe blank in S3 at a cooling rate of 80°C / min until the temperature reaches 480°C, then heating the cooled composite pipe blank to a temperature of 960°C and then keeping it warm. After keeping warm, the composite pipe blank is transported to a quenching system for quenching and cooling using a quenching liquid. The quenching is performed by internal spraying and external showering. The inner lining pipe is cooled by a quenching liquid, and the outer base pipe is cooled by water. After the quenching is completed, the steel pipe is transported to a tempering furnace for tempering to obtain a preliminary composite steel pipe. The tempering furnace temperature is 775°C.

[0094] S5: The preliminary composite steel pipe of S4 is taken out of the furnace and cooled to obtain a corrosion-resistant composite seamless steel pipe.

[0095] During the S2 pouring process, the centrifugal rotation speed is 9r / s.

[0096] During the S2 pouring process, the thickness ratio between the inner lining pipe and the outer base pipe is 3:0.9.

[0097] During the S3 rolling process, the rolling speed was 6.5 m / min, the rotating speed of the rotary table was 190 r / min, the inlet temperature of the tube rolling mill was 1110° C., and the outlet temperature was 915° C.

[0098] During the S4 heat treatment process, the insulation time during heating and insulation is controlled according to the wall thickness coefficient of 2min / mm.

[0099] During the S4 heat treatment process, the tempering holding time during tempering is controlled according to the wall thickness coefficient of 3min / mm.

[0100] The preparation of the quenching liquid includes the following contents:

[0101] Q1: Weigh 70 parts of paraffin-based white oil by weight, heat to 58°C, add 2.5 parts of sodium dioctyl sulfonate dibutyrate and 0.55 parts of alkylated diphenylamine, stir evenly, and obtain quenching prefabricated liquid A for standby use;

[0102] Q2: Weigh 28 parts of 100SN base oil by weight, add 1.3 parts of polyisobutylene succinate at room temperature, stir evenly, and obtain quenching prefabricated liquid B;

[0103] Q3: Under stirring conditions, the quenching pre-liquid B prepared in Q2 is added dropwise to the quenching pre-liquid A prepared in Q1, stirred for 25 minutes, and cooled to room temperature to obtain the quenching liquid.

[0104] Example 5

[0105] A corrosion-resistant composite seamless steel pipe comprises an outer base pipe and an inner liner pipe, wherein the inner liner pipe is located inside the outer base pipe.

[0106] The raw materials of the outer layer base pipe include the following components in percentage by mass: C: 0.21%; Si: 0.28%; Cr: 1.1%; Mn: 0.35%; W: 0.21%; Cu: 0.065%; P: 0.010%; S: 0.005%, and the balance is Fe; the raw materials of the inner lining pipe include the following components in percentage by mass: C: 0.08%; Si: 0.32%; Cr: 19.0%; Ni: 8.3%; Al: 0.17%; Mn: 0.7%; Ti: 0.13%; P: 0.010%; S: 0.005%, and the balance is Fe.

[0107] A preparation process of a corrosion-resistant composite seamless steel pipe comprises the following steps:

[0108] S1: After mixing the raw materials of the outer layer base pipe, molten steel A is smelted through the process of converter + LF furnace refining + vacuum degassing; after mixing the raw materials of the inner liner pipe, molten steel B is smelted through the process of converter + LF furnace refining + vacuum degassing;

[0109] S2: Using the centrifugal casting method, the outer base pipe is cast using molten steel A, and after the outer base pipe is solidified, the inner liner pipe is cast inside the outer base pipe using molten steel B to form a composite pipe blank;

[0110] S3: rolling the composite tube blank in S2 to obtain a composite tube blank;

[0111] S4: cooling the composite tube blank in S3 at a cooling rate of 80°C / min until the temperature reaches 540°C, then heating the cooled composite tube blank to a temperature of 970°C and then keeping it warm. After keeping warm, the composite tube blank is transported to a quenching system for quenching and cooling using a quenching liquid. The quenching is performed by internal spraying and external showering. The inner liner is cooled by a quenching liquid, and the outer base tube is cooled by water. After the quenching is completed, the steel pipe is transported to a tempering furnace for tempering to obtain a preliminary composite steel pipe. The tempering furnace temperature is 780°C.

[0112] S5: The preliminary composite steel pipe of S4 is taken out of the furnace and cooled to obtain a corrosion-resistant composite seamless steel pipe.

[0113] During the S2 pouring process, the centrifugal rotation speed is 11r / s.

[0114] During the S2 pouring process, the thickness ratio between the inner lining pipe and the outer base pipe is 3:1.1.

[0115] During the S3 rolling process, the rolling speed was 7.5 m / min, the rotating speed of the rotary table was 230 r / min, the inlet temperature of the tube rolling mill was 1130° C., and the outlet temperature was 925° C.

[0116] During the S4 heat treatment process, the insulation time during heating and insulation is controlled according to the wall thickness coefficient of 2min / mm.

[0117] During the S4 heat treatment process, the tempering holding time during tempering is controlled according to the wall thickness coefficient of 3min / mm.

[0118] The preparation of the quenching liquid includes the following contents:

[0119] Q1: Weigh 70 parts of paraffin-based white oil by weight, heat to 63°C, add 3.5 parts of sodium dioctyl sulfonate dibutyrate and 0.65 parts of alkylated diphenylamine, stir evenly, and obtain quenching prefabricated liquid A for standby use;

[0120] Q2: Weigh 33 parts of 100SN base oil by weight, add 1.6 parts of polyisobutylene succinate at room temperature, stir evenly, and obtain quenching prefabricated liquid B;

[0121] Q3: Under stirring conditions, the quenching pre-liquid B prepared in Q2 is added dropwise to the quenching pre-liquid A prepared in Q1, stirred for 35 minutes, and cooled to room temperature to obtain the quenching liquid.

[0122] Comparative Example 1

[0123] The only difference from Example 1 is that no tungsten is added to the chemical composition of the outer substrate tube.

[0124] A corrosion-resistant composite seamless steel pipe comprises an outer base pipe and an inner liner pipe, wherein the inner liner pipe is located inside the outer base pipe.

[0125] The raw materials of the outer layer base pipe include the following components in percentage by mass: C: 0.2%; Si: 0.25%; Cr: 1.0%; Mn: 0.3%; Cu: 0.06%; P: 0.010%; S: 0.005%, and the balance is Fe; the raw materials of the inner lining pipe include the following components in percentage by mass: C: 0.08%; Si: 0.30%; Cr: 18.0%; Ni: 8.0%; Al: 0.15%; Mn: 0.6%; Ti: 0.10%; P: 0.010%; S: 0.005%, and the balance is Fe.

[0126] A preparation process of a corrosion-resistant composite seamless steel pipe comprises the following steps:

[0127] S1: After mixing the raw materials of the outer layer base pipe, molten steel A is smelted through the process of converter + LF furnace refining + vacuum degassing; after mixing the raw materials of the inner liner pipe, molten steel B is smelted through the process of converter + LF furnace refining + vacuum degassing;

[0128] S2: Using the centrifugal casting method, the outer base pipe is cast using molten steel A, and after the outer base pipe is solidified, the inner liner pipe is cast inside the outer base pipe using molten steel B to form a composite pipe blank;

[0129] S3: rolling the composite tube blank in S2 to obtain a composite tube blank;

[0130] S4: cooling the composite tube blank in S3 at a cooling rate of 80°C / min until the temperature reaches 500°C, then heating the cooled composite tube blank to a temperature of 965°C and then keeping it warm, after keeping it warm, transporting the composite tube blank to a quenching system and using a quenching liquid for quenching and cooling, the quenching adopts an internal spraying and external showering method, the inner lining tube is cooled by a quenching liquid, and the outer base tube is cooled by water, after the quenching is completed, the steel pipe is transported to a tempering furnace for tempering to obtain a preliminary composite steel pipe, and the tempering furnace temperature is 780°C;

[0131] S5: The preliminary composite steel pipe of S4 is taken out of the furnace and cooled to obtain a corrosion-resistant composite seamless steel pipe.

[0132] During the S2 pouring process, the centrifugal rotation speed is 10r / s.

[0133] During the S2 pouring process, the thickness ratio between the inner lining pipe and the outer base pipe is 3:1.

[0134] During the S3 rolling process, the rolling speed is 7 m / min, the rotating speed of the rotary table is 180 r / min, the inlet temperature of the tube rolling mill is 1120° C., and the outlet temperature is 920° C.

[0135] During the S4 heat treatment process, the insulation time during heating and insulation is controlled according to the wall thickness coefficient of 2min / mm.

[0136] During the S4 heat treatment process, the tempering holding time during tempering is controlled according to the wall thickness coefficient of 3min / mm.

[0137] The preparation of the quenching liquid includes the following contents:

[0138] Q1: Weigh 70 parts of paraffin-based white oil by weight, heat to 60°C, add 3 parts of sodium dioctyl sulfonate dibutyrate and 0.6 parts of alkylated diphenylamine, stir evenly, and obtain quenching prefabricated liquid A for standby use;

[0139] Q2: Weigh 30 parts of 100SN base oil by weight, add 1.5 parts of polyisobutylene succinate at room temperature, stir evenly, and obtain quenching prefabricated liquid B;

[0140] Q3: Under stirring conditions, the quenching pre-liquid B prepared in Q2 is added dropwise to the quenching pre-liquid A prepared in Q1, stirred for 30 minutes, and cooled to room temperature to obtain the quenching liquid.

[0141] Comparative Example 2

[0142] The only difference from Example 1 is that polyisobutylene succinate is not added in the preparation of the quenching liquid.

[0143] A corrosion-resistant composite seamless steel pipe comprises an outer base pipe and an inner liner pipe, wherein the inner liner pipe is located inside the outer base pipe.

[0144] The raw materials of the outer layer base pipe include the following components in percentage by mass: C: 0.2%; Si: 0.25%; Cr: 1.0%; Mn: 0.3%; W: 0.20%; Cu: 0.06%; P: 0.010%; S: 0.005%, and the balance is Fe; the raw materials of the inner lining pipe include the following components in percentage by mass: C: 0.08%; Si: 0.30%; Cr: 18.0%; Ni: 8.0%; Al: 0.15%; Mn: 0.6%; Ti: 0.10%; P: 0.010%; S: 0.005%, and the balance is Fe.

[0145] A preparation process of a corrosion-resistant composite seamless steel pipe comprises the following steps:

[0146] S1: After mixing the raw materials of the outer layer base pipe, molten steel A is smelted through the process of converter + LF furnace refining + vacuum degassing; after mixing the raw materials of the inner liner pipe, molten steel B is smelted through the process of converter + LF furnace refining + vacuum degassing;

[0147] S2: Using the centrifugal casting method, the outer base pipe is cast using molten steel A, and after the outer base pipe is solidified, the inner liner pipe is cast inside the outer base pipe using molten steel B to form a composite pipe blank;

[0148] S3: rolling the composite tube blank in S2 to obtain a composite tube blank;

[0149] S4: cooling the composite tube blank in S3 at a cooling rate of 80°C / min until the temperature reaches 500°C, then heating the cooled composite tube blank to a temperature of 965°C and then keeping it warm, after keeping it warm, transporting the composite tube blank to a quenching system and using a quenching liquid for quenching and cooling, the quenching adopts an internal spraying and external showering method, the inner lining tube is cooled by a quenching liquid, and the outer base tube is cooled by water, after the quenching is completed, the steel pipe is transported to a tempering furnace for tempering to obtain a preliminary composite steel pipe, and the tempering furnace temperature is 780°C;

[0150] S5: The preliminary composite steel pipe of S4 is taken out of the furnace and cooled to obtain a corrosion-resistant composite seamless steel pipe.

[0151] During the S2 pouring process, the centrifugal rotation speed is 10r / s.

[0152] During the S2 pouring process, the thickness ratio between the inner lining pipe and the outer base pipe is 3:1.

[0153] During the S3 rolling process, the rolling speed is 7 m / min, the rotating speed of the rotary table is 180 r / min, the inlet temperature of the tube rolling mill is 1120° C., and the outlet temperature is 920° C.

[0154] During the S4 heat treatment process, the insulation time during heating and insulation is controlled according to the wall thickness coefficient of 2min / mm.

[0155] During the S4 heat treatment process, the tempering holding time during tempering is controlled according to the wall thickness coefficient of 3min / mm.

[0156] The preparation of the quenching liquid includes the following contents:

[0157] Q1: Weigh 70 parts of paraffin-based white oil by weight, heat to 60°C, add 3 parts of sodium dioctyl sulfonate dibutyrate and 0.6 parts of alkylated diphenylamine, stir evenly, and obtain quenching prefabricated liquid A for standby use;

[0158] Q2: Weigh 30 parts of 100SN base oil by weight to obtain quenching prefabricated liquid B;

[0159] Q3: Under stirring conditions, the quenching pre-liquid B prepared in Q2 is added dropwise to the quenching pre-liquid A prepared in Q1, stirred for 30 minutes, and cooled to room temperature to obtain the quenching liquid.

[0160] Comparative Example 3

[0161] The only difference from Example 1 is that during the quenching treatment, both the outer base pipe and the inner liner pipe are cooled by quenching liquid.

[0162] A corrosion-resistant composite seamless steel pipe comprises an outer base pipe and an inner liner pipe, wherein the inner liner pipe is located inside the outer base pipe.

[0163] In terms of mass percentage, the raw materials of the outer layer base pipe include the following components: C: 0.2%; Si: 0.25%; Cr: 1.0%; Mn: 0.3%; W: 0.20%; Cu: 0.06%; P: 0.010%; S: 0.005%, and the balance is Fe; in terms of mass percentage, the raw materials of the inner lining pipe include the following components: C: 0.08%; Si: 0.30%; Cr: 18.0%; Ni: 8.0%; Al: 0.15%; Mn: 0.6%; Ti: 0.10%; P: 0.010%; S: 0.005%, and the balance is Fe.

[0164] A preparation process of a corrosion-resistant composite seamless steel pipe comprises the following steps:

[0165] S1: After mixing the raw materials of the outer layer base pipe, molten steel A is smelted through the process of converter + LF furnace refining + vacuum degassing; after mixing the raw materials of the inner liner pipe, molten steel B is smelted through the process of converter + LF furnace refining + vacuum degassing;

[0166] S2: Using the centrifugal casting method, the outer base pipe is cast using molten steel A, and after the outer base pipe is solidified, the inner liner pipe is cast inside the outer base pipe using molten steel B to form a composite pipe blank;

[0167] S3: rolling the composite tube blank in S2 to obtain a composite tube blank;

[0168] S4: cooling the composite tube blank in S3 at a cooling rate of 80°C / min until the temperature reaches 500°C, then heating the cooled composite tube blank to a temperature of 965°C and then keeping it warm, after keeping it warm, transporting the composite tube blank to a quenching system and using a quenching liquid for quenching and cooling, the quenching adopts an internal spraying and external showering method, the inside is cooled by a quenching liquid, and the outside is cooled by a quenching liquid, after the quenching is completed, the steel pipe is transported to a tempering furnace for tempering to obtain a preliminary composite steel pipe, and the tempering furnace temperature is 780°C;

[0169] S5: The preliminary composite steel pipe of S4 is taken out of the furnace and cooled to obtain a corrosion-resistant composite seamless steel pipe.

[0170] During the S2 pouring process, the centrifugal rotation speed is 10r / s.

[0171] During the S2 pouring process, the thickness ratio between the inner lining pipe and the outer base pipe is 3:1.

[0172] During the S3 rolling process, the rolling speed is 7 m / min, the rotating speed of the rotary table is 180 r / min, the inlet temperature of the tube rolling mill is 1120° C., and the outlet temperature is 920° C.

[0173] During the S4 heat treatment process, the insulation time during heating and insulation is controlled according to the wall thickness coefficient of 2min / mm.

[0174] During the S4 heat treatment process, the tempering holding time during tempering is controlled according to the wall thickness coefficient of 3min / mm.

[0175] The preparation of the quenching liquid includes the following contents:

[0176] Q1: Weigh 70 parts of paraffin-based white oil by weight, heat to 60°C, add 3 parts of sodium dioctyl sulfonate dibutyrate and 0.6 parts of alkylated diphenylamine, stir evenly, and obtain quenching prefabricated liquid A for standby use;

[0177] Q2: Weigh 30 parts of 100SN base oil by weight, add 1.5 parts of polyisobutylene succinate at room temperature, stir evenly, and obtain quenching prefabricated liquid B;

[0178] Q3: Under stirring conditions, the quenching pre-liquid B prepared in Q2 is added dropwise to the quenching pre-liquid A prepared in Q1, stirred for 30 minutes, and cooled to room temperature to obtain the quenching liquid.

[0179] Comparative Example 4

[0180] The only difference from Example 1 is that tungsten is not added to the chemical composition of the outer layer base tube, and during the quenching treatment, the inside and outside of the composite steel tube are cooled by quenching liquid.

[0181] A corrosion-resistant composite seamless steel pipe comprises an outer base pipe and an inner liner pipe, wherein the inner liner pipe is located inside the outer base pipe.

[0182] The raw materials of the outer layer base pipe include the following components in percentage by mass: C: 0.2%; Si: 0.25%; Cr: 1.0%; Mn: 0.3%; Cu: 0.06%; P: 0.010%; S: 0.005%, and the balance is Fe; the raw materials of the inner lining pipe include the following components in percentage by mass: C: 0.08%; Si: 0.30%; Cr: 18.0%; Ni: 8.0%; Al: 0.15%; Mn: 0.6%; Ti: 0.10%; P: 0.010%; S: 0.005%, and the balance is Fe.

[0183] A preparation process of a corrosion-resistant composite seamless steel pipe comprises the following steps:

[0184] S1: After mixing the raw materials of the outer layer base pipe, molten steel A is smelted through the process of converter + LF furnace refining + vacuum degassing; after mixing the raw materials of the inner liner pipe, molten steel B is smelted through the process of converter + LF furnace refining + vacuum degassing;

[0185] S2: Using the centrifugal casting method, the outer base pipe is cast using molten steel A, and after the outer base pipe is solidified, the inner liner pipe is cast inside the outer base pipe using molten steel B to form a composite pipe blank;

[0186] S3: rolling the composite tube blank in S2 to obtain a composite tube blank;

[0187] S4: cooling the composite tube blank in S3 at a cooling rate of 80°C / min until the temperature reaches 500°C, then heating the cooled composite tube blank to a temperature of 965°C and then keeping it warm, after keeping it warm, transporting the composite tube blank to a quenching system and using a quenching liquid for quenching and cooling, the quenching adopts an internal spraying and external showering method, the inside is cooled by a quenching liquid, and the outside is also cooled by a quenching liquid, after the quenching is completed, the steel pipe is transported to a tempering furnace for tempering to obtain a preliminary composite steel pipe, and the tempering furnace temperature is 780°C;

[0188] S5: The preliminary composite steel pipe of S4 is taken out of the furnace and cooled to obtain a corrosion-resistant composite seamless steel pipe.

[0189] During the S2 pouring process, the centrifugal rotation speed is 10r / s.

[0190] During the S2 pouring process, the thickness ratio between the inner lining pipe and the outer base pipe is 3:1.

[0191] During the S3 rolling process, the rolling speed is 7 m / min, the rotating speed of the rotary table is 180 r / min, the inlet temperature of the tube rolling mill is 1120° C., and the outlet temperature is 920° C.

[0192] During the S4 heat treatment process, the insulation time during heating and insulation is controlled according to the wall thickness coefficient of 2min / mm.

[0193] During the S4 heat treatment process, the tempering holding time during tempering is controlled according to the wall thickness coefficient of 3min / mm.

[0194] The preparation of the quenching liquid includes the following contents:

[0195] Q1: Weigh 70 parts of paraffin-based white oil by weight, heat to 60°C, add 3 parts of sodium dioctyl sulfonate dibutyrate and 0.6 parts of alkylated diphenylamine, stir evenly, and obtain quenching prefabricated liquid A for standby use;

[0196] Q2: Weigh 30 parts of 100SN base oil by weight, add 1.5 parts of polyisobutylene succinate at room temperature, stir evenly, and obtain quenching prefabricated liquid B;

[0197] Q3: Under stirring conditions, the quenching pre-liquid B prepared in Q2 is added dropwise to the quenching pre-liquid A prepared in Q1, stirred for 30 minutes, and cooled to room temperature to obtain the quenching liquid.

[0198] Proven results

[0199] The corrosion-resistant composite steel pipes prepared in the embodiments and comparative examples were subjected to an interface bonding strength test. The specific detection method is as follows: after the steel pipe is cut, a CMT 5105 microcomputer-controlled electronic universal (tensile) testing machine is used to clamp the inner and outer sides of the steel pipe, and the tensile speed is controlled to be 1 mm / min. The tensile force at the time of fracture is recorded, wherein the interface bonding strength = tensile force / interface contact area. The specific test results are shown in Table 1.

[0200] Table 1

[0201] Interface bonding strength / Mpa Example 1 72.6 Example 2 70.3 Example 3 71.6 Example 4 71.2 Example 5 72.1 Comparative Example 1 66.5 Comparative Example 2 68.8 Comparative Example 3 64.7 Comparative Example 4 61.9

[0202] From the interfacial bonding strength of the corrosion-resistant composite seamless steel pipes in Examples 1 to 5 in Table 1, it can be seen that the corrosion-resistant composite seamless steel pipes prepared in the present invention have excellent mechanical properties.

[0203] The only difference between Comparative Example 1 and Example 1 is that no tungsten is added to the chemical composition of the outer layer substrate tube.

[0204] The interface bonding strength of the corrosion-resistant composite seamless steel pipe prepared in Comparative Example 1 is significantly lower than the interface bonding strength of the corrosion-resistant composite seamless steel pipe prepared in Example 1.

[0205] The above results show that the addition of tungsten improves the bonding tightness between the inner liner pipe and the outer base pipe of the corrosion-resistant composite seamless steel pipe, and improves the service quality of the composite steel pipe.

[0206] The only difference between Comparative Example 2 and Example 1 is that polyisobutylene succinate is not added in the preparation of the quenching liquid.

[0207] The interface bonding strength of the corrosion-resistant composite seamless steel pipe prepared in Comparative Example 2 is significantly lower than the interface bonding strength of the corrosion-resistant composite seamless steel pipe prepared in Example 1.

[0208] The above results show that the addition of polyisobutylene succinate in the quenching liquid can improve the quenching performance of the quenching liquid, thereby improving the bonding tightness between the inner liner pipe and the outer base pipe of the corrosion-resistant composite seamless steel pipe, thereby improving the service quality of the composite steel pipe.

[0209] The only difference between Comparative Example 3 and Example 1 is that during the quenching treatment, quenching liquid is used for cooling both inside and outside.

[0210] The interface bonding strength of the corrosion-resistant composite seamless steel pipe prepared in Comparative Example 3 is significantly lower than the interface bonding strength of the corrosion-resistant composite seamless steel pipe prepared in Example 1.

[0211] The above results show that in the preparation process of corrosion-resistant composite seamless steel pipe, the inner liner pipe is cooled by quenching liquid and the outer base pipe is cooled by water. This combined quenching method is more conducive to improving the bonding tightness between the inner liner pipe and the outer base pipe of the corrosion-resistant composite seamless steel pipe.

[0212] The only difference between Comparative Example 4 and Example 1 is that no tungsten is added to the chemical composition of the outer layer base tube, and during the quenching treatment, the inside and outside of the composite steel tube are cooled by quenching liquid.

[0213] The interface bonding strength of the corrosion-resistant composite seamless steel pipe prepared in Comparative Example 4 is significantly lower than the interface bonding strength of the corrosion-resistant composite seamless steel pipe prepared in Example 1.

[0214] In combination with Comparative Example 1 and Comparative Example 3, in the preparation of the corrosion-resistant composite seamless steel pipe, tungsten is added to the outer base pipe component, the inner lining pipe is cooled by the quenching liquid of the present invention and the outer base pipe is water-cooled, and there is a synergistic effect between the two, which can synergistically improve the bonding tightness between the inner lining pipe and the outer base pipe of the corrosion-resistant composite seamless steel pipe, that is, synergistically improve the use quality of the composite steel pipe.

[0215] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A corrosion-resistant composite seamless steel pipe, characterized in that: It comprises an outer layer base pipe and an inner liner pipe, wherein the inner liner pipe is located inside the outer layer base pipe, and the raw materials of the outer layer base pipe include the following components by mass percentage: C: 0.18~0.22%; Si: 0.2~0.3%; Cr: 0.8~1.2%; Mn: 0.2~0.4%; W: 0.18~0.22%; Cu: 0.05~0.07%; P≤0.010％； S≤0.005%, the balance is Fe; the raw materials of the inner lining pipe include the following components in percentage by mass: C: 0.06-0.10%; Si: 0.25-0.35%; Cr: 16.0-20.0%; Ni: 7.5-8.5%; Al: 0.12-0.18%; Mn: 0.4-0.8%; Ti: 0.05-0.15%; P≤0.010%; S≤0.005%, the balance is Fe.

2. The corrosion-resistant composite seamless steel pipe according to claim 1, characterized in that: The raw material of the outer layer substrate tube includes the following components in terms of mass percentage: C: 0.2%; Si: 0.25%; Cr: 1.0%; Mn: 0.3%; W: 0.20%; Cu: 0.06%; P: 0.010%; S: 0.005%, and the balance is Fe.

3. The corrosion-resistant composite seamless steel pipe according to claim 1, characterized in that: The raw material of the inner lining pipe includes the following components in percentage by mass: C: 0.08%; Si: 0.30%; Cr: 18.0%; Ni: 8.0%; Al: 0.15%; Mn: 0.6%; Ti: 0.10%; P: 0.010%; S: 0.005%, and the balance is Fe.

4. A process for preparing a corrosion-resistant composite seamless steel pipe according to any one of claims 1 to 3, comprising the following steps: S1: After mixing the raw materials of the outer layer base pipe, molten steel A is smelted through the process of converter + LF furnace refining + vacuum degassing; after mixing the raw materials of the inner liner pipe, molten steel B is smelted through the process of converter + LF furnace refining + vacuum degassing; S2: Using the centrifugal casting method, the outer base pipe is cast using molten steel A, and after the outer base pipe is solidified, the inner liner pipe is cast inside the outer base pipe using molten steel B to form a composite pipe blank; S3: rolling the composite tube blank in S2 to obtain a composite tube blank; S4: cooling the composite pipe blank in S3 at a cooling rate of 80°C / min until the temperature reaches 450-550°C, then heating the cooled composite pipe blank to a temperature of 950-980°C and then keeping it warm. After keeping warm, the composite pipe blank is transported to a quenching system for quenching and cooling. The quenching is performed by internal spraying and external showering. The inner lining pipe is cooled by quenching liquid and the outer base pipe is cooled by water. After the quenching is completed, the steel pipe is transported to a tempering furnace for tempering to obtain a preliminary composite steel pipe. The tempering furnace temperature is 770-790°C. S5: The preliminary composite steel pipe of S4 is taken out of the furnace and cooled to obtain a corrosion-resistant composite seamless steel pipe.

5. The process for preparing a corrosion-resistant composite seamless steel pipe according to claim 4, characterized in that: During the S2 pouring process, the centrifugal rotation speed is 8 to 12 r / s.

6. The process for preparing a corrosion-resistant composite seamless steel pipe according to claim 4, characterized in that: During the S2 pouring process, the thickness ratio between the inner lining pipe and the outer base pipe is 3:0.8-1.

2.

7. The process for preparing a corrosion-resistant composite seamless steel pipe according to claim 4, characterized in that: During the S3 rolling process, the rolling speed is 6-8 m / min, the rotating speed of the rotary table is 180-240 r / min, the inlet temperature of the tube rolling mill is 1100-1140°C, and the outlet temperature is 910-930°C.

8. The process for preparing a corrosion-resistant composite seamless steel pipe according to claim 4, characterized in that: During the S4 heat treatment process, the insulation time during heating and insulation is controlled according to the wall thickness coefficient of 2min / mm.

9. The process for preparing a corrosion-resistant composite seamless steel pipe according to claim 4, characterized in that: During the S4 heat treatment process, the tempering holding time during tempering is controlled according to the wall thickness coefficient of 3min / mm.

10. The process for preparing a corrosion-resistant composite seamless steel pipe according to claim 4, characterized in that: The preparation of the quenching liquid includes the following contents: Q1: Weigh 70 parts of paraffin-based white oil by weight, heat to 55-65° C., add 2-4 parts of sodium dioctyl sulfonate dibutyrate and 0.5-0.7 parts of alkylated diphenylamine, stir evenly, and obtain quenching preformed liquid A for standby use; Q2: Weigh 25-35 parts of 100SN base oil by weight, add 1.2-1.8 parts of polyisobutylene succinate at room temperature, stir evenly, and obtain quenching prefabricated liquid B; Q3: Under stirring conditions, the quenching pre-liquid B prepared in Q2 is added dropwise to the quenching pre-liquid A prepared in Q1, stirred for 20 to 40 minutes, and cooled to room temperature to obtain the quenching liquid.