Precipitation strengthening type high-temperature alloy pipe and preparation method thereof

Abstract

The invention belongs to the technical field of high-temperature alloy pipe preparation, and particularly relates to a precipitation strengthening type high-temperature alloy pipe and a preparation method thereof.The preparation method comprises the steps that a precipitation strengthening type nickel-iron-based high-temperature alloy pipe subjected to hot extrusion treatment is heated to 180-200 DEG C below the TiC phase precipitation temperature, then heat preservation is conducted for 3.0-3.5 h, rapid cooling is conducted after heat preservation is finished, and the precipitation strengthening type high-temperature alloy pipe is obtained; the temperature rise rate during heating is 12-15 DEG C / min; the precipitation strengthening type nickel-iron-based high-temperature alloy pipe subjected to high-temperature solution treatment is cold-rolled to the target size, and a cold-rolled pipe is obtained; the rolling deformation is 35%-40%; the cold rolled pipe is subjected to oil removal and drying; the cleaned cold rolled pipe is heated to 260-280 DEG C below the TiC phase precipitation temperature, then heat preservation is conducted for 2.5-3.0 h, air cooling is conducted after heat preservation is finished, the precipitation strengthening type high-temperature alloy pipe is obtained, and the temperature rise rate during heating is 10-12 DEG C / min. The method can solve the problem that in the prior art, no method is suitable for eliminating the Ti-rich phase on the inner wall of the ferro-nickel high-temperature alloy pipe, and the surface quality problem caused by the method is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of high-temperature alloy pipe preparation, and specifically relates to a precipitation-strengthened high-temperature alloy pipe and a preparation method thereof. Background Art

[0002] Electricity is an indispensable energy carrier for all walks of life in modern society, and the power industry has become an important material basis for sustainable economic development. In recent years, with the successive power outages in different regions and the limitations of new energy, the role of coal-fired power in ensuring supply has become more prominent. The energy consumption of thermal power generation has brought huge environmental pollution problems. Therefore, the development of high-parameter ultra-supercritical power generation technology to reduce coal consumption, save resources, and improve environmental pollution is the main direction of technological development in the thermal power industry. Materials and component preparation technology are the key factors restricting high-parameter ultra-supercritical units. The superheater / reheater is the most demanding component in the unit components that withstands temperature and pressure. The commercial new austenitic heat-resistant steel Super304H and HR3C can still meet the design requirements of the superheater / reheater of 600-620℃ units, but for higher parameter 650℃ and 700℃ units, nickel-based and nickel-iron-based high-temperature alloys with better comprehensive performance are required.

[0003] In some precipitation-strengthened nickel-based and nickel-iron-based high-temperature alloys, Ti is an important component element in the alloy. Together with Al and matrix Ni, they are important components of the precipitation-strengthened γ′ phase. The γ′ precipitated in the alloy can promote the high-temperature strength of the alloy. The uniform distribution of Ti in the alloy structure has an important influence on the comprehensive properties of the alloy. In the preparation process of high-temperature alloy pipes, Ti elements are easily enriched on the inner wall of the pipe to produce a layer of MX phase. Excessive MX phases will make the grain boundaries brittle and lead to reduced creep plasticity. Therefore, the use of effective methods to avoid or reduce the enrichment of MX phases on the inner wall of the pipe is important for the quality control of alloy parts and ensuring the comprehensive performance of alloy pipes.

[0004] High-parameter ultra-supercritical power generation technology places high demands on the surface quality improvement of the superheater / reheater components of the unit. The surface optimization of the components plays an important role in breaking through the bottleneck of high-temperature materials in power plants. In order to improve the thermal efficiency of coal-fired units, the specifications of the superheater / reheater are developing towards a trend of small pipe diameter and large wall thickness. Usually, the wall thickness to outer diameter ratio of the subcritical unit is less than 0.2, and the wall thickness to outer diameter ratio of the superheater tube of the ultra-supercritical unit is 0.2-0.3. The wall thickness to outer diameter ratio of the 650℃ and 700℃ units will be larger, so the control of the surface quality of the inner wall of small-diameter pipes will be more difficult. During operation, the pipe is subjected to the pulse high pressure of the internal medium. The MX phase enriched on the inner or outer wall of the pipe will become a crack source due to stress concentration. Under the action of stress, there is a risk of cracking, resulting in unplanned shutdown accidents and endangering the safe operation of the unit. In traditional processes, the improvement of the inner and outer wall surfaces of pipes only relies on the final inner and outer wall thinning treatment. This process is generally time-consuming, and as the length of the pipe increases, the difficulty of grinding and polishing the inner and outer walls also increases significantly, which is not conducive to the industrial mass production of high-temperature alloy pipes. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a precipitation-strengthened high-temperature alloy tube and a preparation method thereof. The present invention can solve the problem that there is no suitable method for eliminating the Ti-rich phase on the inner wall of the nickel-iron high-temperature alloy tube in the prior art, as well as the surface quality problems caused thereby.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A method for preparing a precipitation-strengthened high-temperature alloy pipe comprises:

[0008] High temperature solution treatment: heat the precipitation-strengthened nickel-iron-based high temperature alloy tube that has undergone hot extrusion treatment to 180-200°C below the TiC phase precipitation temperature, then keep it warm for 3.0-3.5 hours, and quickly cool it after the end of the warming period; wherein, the heating rate during heating is 12-15°C / min;

[0009] Cold rolling process: cold rolling the precipitation-strengthened nickel-iron-based high-temperature alloy tube after high-temperature solid solution treatment to the target size to obtain a cold-rolled tube; wherein the rolling deformation of the cold rolling is 35%-40%;

[0010] Surface cleaning process: degreasing the cold rolled tube, removing the cleaning fluid, and drying;

[0011] Low-temperature solution treatment: heating the cold-rolled tube after surface cleaning to 260-280°C below the TiC phase precipitation temperature, then keeping it warm for 2.5-3.0 hours, and air cooling after the end of the insulation to obtain the precipitation-strengthened high-temperature alloy tube; wherein the heating rate during heating is 10-12°C / min.

[0012] Preferably, during the high-temperature solution treatment, rapid cooling is performed by water quenching.

[0013] Preferably, the precipitation-strengthened nickel-iron-based high-temperature alloy tube after high-temperature solution treatment has a yield strength of not less than 340MPa, a tensile strength of not less than 695MPa, a room temperature elongation of more than 47%, and an impact resistance of not less than 135J / cm 2 .

[0014] Preferably, the cleaning liquid used in degreasing is Na 2 CO 3 , NaOH, sodium silicate, ethanol and water, among which Na 2 CO 3 The mass ratio of NaOH, sodium silicate, ethanol and water is (3.0-4.5):(3.5-5.5):(2-6):(2-4):(30-60).

[0015] Preferably, during the degreasing process, the cleaning liquid temperature is 80-100° C. and the cleaning time is 40-50 min.

[0016] Preferably, the oil removal process uses a cleaning fluid for circulating cleaning.

[0017] Preferably, after the low-temperature solution treatment is completed, the pipe after the low-temperature solution treatment is pressure straightened and descaled.

[0018] The present invention also provides a precipitation-strengthened high-temperature alloy pipe, which is prepared by the preparation method of the present invention as described above.

[0019] Preferably, in terms of mass percentage, the components of the precipitation-strengthened high-temperature alloy pipe include: Ti: 1.0% to 4.5%, Al: 1.0% to 4.5%, Ta: ≤0.1%, Co: 1.0% to 3.4%, W: 0.1% to 1.2%; Si: 0.02% to 1.3%; C: 0.09% to 1.0%, Cr: 12% to 24%, Fe: 20% to 34%, Pb: 0 to 0.005%, Bi: 0.0001% to 0.0005%, Se: 0.002% to 0.005%, and the balance is Ni.

[0020] Preferably, the precipitation-strengthened high-temperature alloy tube has a yield strength of not less than 620 MPa, a tensile strength of not less than 1025 MPa, an elongation at room temperature of more than 35%, and an impact resistance of not less than 89 J / cm 2 .

[0021] The present invention has the following beneficial effects:

[0022] In the preparation method of the precipitation-strengthened high-temperature alloy pipe provided by the present invention, the surface of the high-temperature alloy pipe can be improved by using the high-temperature solution treatment and the low-temperature solution treatment of the present invention, so that the precipitation-strengthened high-temperature alloy pipe can avoid the formation of carbon enrichment at the inner and outer walls during the solution treatment process. Therefore, the external C element and the Ti element in the alloy cannot combine to form an MX phase mainly composed of TiC, and the formation of the MX phase on the inner and outer walls can be avoided from the source. It can be seen that the present invention effectively solves the problem in the prior art that there is no method suitable for eliminating the Ti-rich phase on the inner wall of the nickel-iron high-temperature alloy pipe, and the surface quality problem caused by it. Furthermore, the present invention can effectively improve the yield rate of the intermediate product and the supply state of the nickel-iron-based high-temperature alloy pipe, greatly improve the surface quality of the pipe, and reduce the cost of component preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a cross-sectional morphology near the surface of a precipitation-strengthened high-temperature alloy tube prepared in Example 1 of the present invention;

[0025] Figure 2 This is a near-surface cross-sectional morphology of a precipitation-strengthened high-temperature alloy tube prepared in Example 2 of the present invention;

[0026] Figure 3 This is a near-surface cross-sectional morphology of a precipitation-strengthened high-temperature alloy tube prepared in Example 3 of the present invention;

[0027] Figure 4 This is a cross-sectional morphology near the surface of a precipitation-strengthened high-temperature alloy tube prepared in Example 4 of the present invention;

[0028] Figure 5 This is a low-magnification morphology image of a cross section near the surface of the alloy prepared in Comparative Example 1 of the present invention;

[0029] Figure 6 This is a high-magnification morphology image of a cross section near the surface of an alloy prepared in Comparative Example 1 of the present invention;

[0030] Figure 7 This is the EDS spectrum of the surface precipitation phase of the alloy prepared in Comparative Example 1 of the present invention;

[0031] Figure 8 This is a low-magnification morphology image of a cross section near the surface of the alloy prepared in Comparative Example 2 of the present invention;

[0032] Fig. 9 This is a high-magnification morphology image of a cross section near the surface of the alloy prepared in Comparative Example 2 of the present invention;

[0033] Fig.10 This is the EDS energy spectrum of the surface precipitation phase of the alloy prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0034] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0035] The method for preparing a precipitation-strengthened high-temperature alloy pipe of the present invention is a method for eliminating the Ti-rich phase on the inner wall during the preparation process of the precipitation-strengthened high-temperature alloy pipe, comprising the following steps:

[0036] Step 1) subjecting the hot extruded precipitation-strengthened nickel-iron-based high-temperature alloy tube to a high-temperature solution treatment, wherein the specific process of the high-temperature solution treatment comprises: heating the alloy tube from room temperature to 180-200° C. below the TiC phase precipitation temperature, then keeping the temperature for 3.0-3.5 hours, and then rapidly cooling the tube by water quenching; wherein the heating rate during heating is 12-15° C. / min.

[0037] Step 2) cold-deform the alloy tube after high-temperature solid solution in step 1) on a tube rolling mill, rolling the alloy tube to a target size to obtain a cold-rolled tube; wherein the rolling deformation is 35%-40%;

[0038] Step 3) Na 2 CO 3 A cleaning solution is prepared by mixing NaOH, sodium silicate, ethanol and water in a mass ratio of (3.0-4.5): (3.5-5.5): (2-6): (2-4): (30-60). The cold-rolled alloy pipe is placed in a cleaning tank for circulation and degreasing to remove the lubricating oil on the surface of the alloy pipe. The cleaning solution temperature is 80-100°C and the cleaning time is 40-50 minutes. After that, the cleaning solution on the surface of the cold-rolled pipe is washed away and then dried. The cleaning of the cold-rolled pipe is completed.

[0039] Step 4) The cleaned cold-rolled tube is subjected to low-temperature solution treatment, and the low-temperature solution treatment process specifically includes: heating the cold-rolled tube treated in step 3) from room temperature to 260-280°C below the TiC phase precipitation temperature, keeping the temperature for 2.5-3.0 hours, and then air cooling; wherein the heating rate during heating is 10-12°C / min.

[0040] 5) Pressure straightening and descaling.

[0041] The preparation method of the precipitation-strengthened high-temperature alloy pipe of the present invention is suitable for precipitation-strengthened high-temperature alloy pipes with the following components. In terms of mass percentage, the components of the precipitation-strengthened high-temperature alloy pipes meet the following conditions: Ti: 1.0% to 4.5%, Al: 1.0% to 4.5%, Ta: ≤0.1%, Co: 1.0% to 3.4%, W: 0.1% to 1.2%; Si: 0.02% to 1.3%; C: 0.09% to 1.0%, Cr: 12% to 24%, Fe: 20% to 34%, Pb: 0 to 0.005%, Bi: 0.0001% to 0.0005%, Se: 0.002% to 0.005%, and the balance is Ni.

[0042] After the precipitation-strengthened high-temperature alloy tube of the present invention is treated in step 1), the yield strength is not less than 340MPa, the tensile strength is not less than 695MPa, the room temperature elongation is greater than 47%, and the impact performance is not less than 135J / cm 2 .

[0043] After the precipitation-strengthened high-temperature alloy tube of the above composition is treated in step 4), the yield strength of the alloy tube is not less than 620MPa, the tensile strength is not less than 1025MPa, the room temperature elongation is above 35%, and the impact performance is not less than 89J / cm 2 .

[0044] Example 1

[0045] In this embodiment, the components in the precipitation-strengthened high-temperature alloy tube include, in terms of mass percentage: Ti: 3.0%, Al: 2.5%, Ta: 0.04%, Co: 2.4%, W: 0.2%; Si: 1.0%; C: 0.3%, Cr: 20%, Fe: 24%, Pb: 0.002%, Bi: 0.0003%, Se: 0.002%, and the balance is Ni. The precipitation-strengthened nickel-iron-based high-temperature alloy tube that has undergone hot extrusion treatment is subjected to high-temperature solid solution treatment. The specific process of the high-temperature solid solution treatment includes: heating the alloy tube from room temperature to 180°C below the TiC phase precipitation temperature at a heating rate of 15°C / min, then keeping it warm for 3.5 hours, and water quenching after the end of the insulation. Afterwards, the alloy tube that has undergone high-temperature solid solution treatment is cold-deformed and rolled on a tube rolling mill, with a rolling deformation of 35%, to obtain a cold-rolled tube;

[0046] Will Na 2 CO 3, NaOH, sodium silicate, ethanol and water are prepared into a cleaning solution in a mass ratio of 3.0:3.9:6:3:50, and then the cold-rolled pipe is placed in a cleaning tank for circulation and degreasing. During the circulation and degreasing, the cleaning liquid temperature is 80°C and the cleaning time is 50 minutes. Then the cleaning liquid on the surface of the cold-rolled pipe is washed away, and then dried, and the cold-rolled pipe cleaning is completed. The cleaned cold-rolled pipe is subjected to low-temperature solid solution treatment. The low-temperature solid solution treatment process specifically includes: heating the cleaned cold-rolled pipe from room temperature at a heating rate of 12°C / min to 270°C below the TiC phase precipitation temperature, and then keeping it warm for 2.5 hours, and air cooling after the end of the insulation. After the low-temperature solid solution treatment, the alloy pipe is pressure straightened and the surface oxide scale is removed.

[0047] Figure 1 This is the cross-sectional morphology of the precipitation-strengthened high-temperature alloy tube near the inner surface in this embodiment. It can be seen that the grain structure on the inner surface is normal and no TiC phase is precipitated.

[0048] Example 2

[0049] In this embodiment, the components in the precipitation-strengthened high-temperature alloy tube include, in terms of mass percentage: Ti: 2.0%, Al: 1.9%, Ta: 0.03%, Co: 3.0%, W: 1.0%; Si: 0.02%; C: 0.03%, Cr: 19%, Fe: 25%, Pb: 0.001%, Bi: 0.0001%, Se: 0.002%, and the balance is Ni. The precipitation-strengthened nickel-iron-based high-temperature alloy tube that has undergone hot extrusion treatment is subjected to high-temperature solid solution treatment. The specific process of the high-temperature solid solution treatment includes: heating the alloy tube from room temperature to 180°C below the TiC phase precipitation temperature at a heating rate of 12°C / min, then keeping the temperature for 3.0 hours, and water quenching after the end of the heat preservation. Afterwards, the alloy tube that has undergone high-temperature solid solution treatment is cold-deformed and rolled on a tube rolling mill, with a rolling deformation of 35%, to obtain a cold-rolled tube;

[0050] Will Na 2 CO 3 , NaOH, sodium silicate, ethanol and water are prepared into a cleaning solution in a mass ratio of 4.3:5.1:5:4:60, and then the cold-rolled pipe is placed in a cleaning tank for circulation and degreasing. During the circulation and degreasing, the cleaning liquid temperature is 100°C and the cleaning time is 40 minutes. Then the cleaning liquid on the surface of the cold-rolled pipe is washed away, and then dried, and the cold-rolled pipe cleaning is completed. The cleaned pipe is subjected to low-temperature solution treatment. The low-temperature solution treatment process specifically includes: heating the cleaned cold-rolled pipe from room temperature at a heating rate of 10°C / min to 280°C below the TiC phase precipitation temperature, and then keeping it warm for 3.0 hours, and air cooling after the end of the insulation. After the low-temperature solution treatment, the alloy pipe is pressure straightened and the surface oxide scale is removed.

[0051] Figure 2 This is the cross-sectional morphology of the precipitation-strengthened high-temperature alloy tube near the inner surface in this embodiment. It can be seen that the grain structure on the inner surface is normal and no TiC phase is precipitated.

[0052] Example 3

[0053] In this embodiment, the components in the precipitation-strengthened high-temperature alloy tube include, by mass percentage: Ti: 1.2%, Al: 1.3%, Ta: 0.09%, Co: 1.0%, W: 0.1%; Si: 0.1%; C: 0.01%, Cr: 15%, Fe: 22%, Pb: 0.001%, Bi: 0.0001%, Se: 0.002%, and the balance is Ni. The precipitation-strengthened nickel-iron-based high-temperature alloy tube that has undergone hot extrusion treatment is subjected to high-temperature solution treatment. The specific process of the high-temperature solution treatment includes: heating the alloy tube from room temperature to 200°C below the TiC phase precipitation temperature at a heating rate of 13°C / min, then keeping it warm for 3 hours and 20 minutes, and water quenching after the end of the insulation. Afterwards, the alloy tube that has undergone high-temperature solution treatment is cold-deformed and rolled on a tube rolling mill, with a rolling deformation of 38%, to obtain a cold-rolled tube;

[0054] Will Na 2 CO 3 , NaOH, sodium silicate, ethanol and water are prepared into a cleaning solution in a mass ratio of 3.8:3.6:5.8:4:30, and then the cold-rolled pipe is placed in a cleaning tank for circulation and degreasing. During the circulation and degreasing, the cleaning liquid temperature is 90°C and the cleaning time is 45 minutes. Then the cleaning liquid on the surface of the cold-rolled pipe is washed away, and then dried, and the cold-rolled pipe cleaning is completed. The cleaned pipe is subjected to low-temperature solution treatment. The low-temperature solution treatment process specifically includes: heating the cleaned cold-rolled pipe from room temperature to 260°C below the TiC phase precipitation temperature at a heating rate of 11°C / min, and then keeping it warm for 2 hours and 50 minutes, and air cooling after the insulation is completed. After the low-temperature solution treatment, the alloy pipe is pressure straightened and the surface oxide scale is removed.

[0055] Figure 3 This is the cross-sectional morphology of the precipitation-strengthened high-temperature alloy tube near the inner surface in this embodiment. It can be seen that the grain structure on the inner surface is normal and no TiC phase is precipitated.

[0056] Example 4

[0057] In this embodiment, the components in the precipitation-strengthened high-temperature alloy tube include, in terms of mass percentage: Ti: 1.5%, Al: 1.8%, Ta: 0.05%, Co: 3.1%, W: 1.0%; Si: 1.1%; C: 0.5%, Cr: 23%, Fe: 22%, Pb: 0.004%, Bi: 0.0002%, Se: 0.004%, and the balance is Ni. The precipitation-strengthened nickel-iron-based high-temperature alloy tube that has undergone hot extrusion treatment is subjected to high-temperature solution treatment. The specific process of the high-temperature solution treatment includes: heating the alloy tube from room temperature to 190°C below the TiC phase precipitation temperature at a heating rate of 13°C / min, then keeping the temperature for 3 hours and 10 minutes, and water quenching after the end of the insulation. Afterwards, the alloy tube that has undergone high-temperature solution treatment is cold-deformed and rolled on a tube rolling mill, with a rolling deformation of 40%, to obtain a cold-rolled tube;

[0058] Will Na 2 CO 3 , NaOH, sodium silicate, ethanol and water are prepared into a cleaning solution in a mass ratio of 4.0:5.0:2:2:40, and then the cold-rolled pipe is placed in a cleaning tank for circulation and degreasing. During the circulation and degreasing, the cleaning liquid temperature is 80°C and the cleaning time is 45 minutes. Then the cleaning liquid on the surface of the cold-rolled pipe is washed away, and then dried, and the cold-rolled pipe cleaning is completed. The cleaned pipe is subjected to low-temperature solution treatment. The low-temperature solution treatment process specifically includes: heating the cleaned cold-rolled pipe from room temperature to 265°C below the TiC phase precipitation temperature at a heating rate of 10°C / min, and then keeping it warm for 2.5 hours, and air cooling after the insulation is completed. After the low-temperature solution treatment, the alloy pipe is pressure straightened and the surface oxide scale is removed.

[0059] Figure 4 This is the cross-sectional morphology of the precipitation-strengthened high-temperature alloy tube near the inner surface in this embodiment. It can be seen that the grain structure on the inner surface is normal and no TiC phase is precipitated.

[0060] Comparative Example 1

[0061] In this comparative example, the components in the precipitation-strengthened high-temperature alloy pipe include, in terms of mass percentage: Ti: 3.0%, Al: 2.5%, Ta: 0.04%, Co: 2.4%, W: 0.2%; Si: 1.0%; C: 0.3%, Cr: 20%, Fe: 24%, Pb: 0.002%, Bi: 0.0003%, Se: 0.002%, and the balance is Ni. The precipitation-strengthened nickel-iron-based high-temperature alloy pipe that has undergone hot extrusion treatment is subjected to high-temperature solution treatment. The specific process of the high-temperature solution treatment includes: heating the alloy pipe from room temperature to 160°C below the TiC phase precipitation temperature at a heating rate of 15°C / min, then keeping it warm for 2.5 hours, and water quenching after the end of the insulation. The alloy pipe after the high-temperature solution treatment is then cold-deformed on a pipe rolling mill, with a rolling deformation of 35%, to obtain a cold-rolled pipe;

[0062] Will Na 2 CO 3 , NaOH, sodium silicate, ethanol and water are prepared into a cleaning solution in a mass ratio of 3.0:3.9:6:3:50, and then the cold-rolled pipe is placed in a cleaning tank for circulation and degreasing. During the circulation and degreasing, the cleaning liquid temperature is 80°C and the cleaning time is 50 minutes. Then the cleaning liquid on the surface of the cold-rolled pipe is washed away, and then dried, and the cold-rolled pipe cleaning is completed. The cleaned cold-rolled pipe is subjected to low-temperature solution treatment. The low-temperature solution treatment process specifically includes: heating the cleaned cold-rolled pipe from room temperature at a heating rate of 12°C / min to 300°C below the TiC phase precipitation temperature, and then keeping it warm for 2.5, and air cooling after the insulation is completed. After the low-temperature solution treatment, the alloy pipe is pressure straightened and the surface oxide scale is removed.

[0063] Figure 5 This is the low-magnification cross-sectional morphology of the precipitation-strengthened high-temperature alloy tube near the inner surface in Comparative Example 1. It can be seen that there are many abnormal precipitated phases in the inner surface crystals and at the grain boundaries. Figure 6 This is the high-magnification morphology of the precipitated phase. Figure 7 is the EDS spectrum result of the corresponding precipitated phase, and the results show that the precipitated phase is TiC phase.

[0064] Comparative Example 2

[0065] In this comparative example, the components in the precipitation-strengthened high-temperature alloy pipe include, in terms of mass percentage: Ti: 2.0%, Al: 1.9%, Ta: 0.03%, Co: 3.0%, W: 1.0%; Si: 0.02%; C: 0.03%, Cr: 19%, Fe: 25%, Pb: 0.001%, Bi: 0.0001%, Se: 0.002%, and the balance is Ni. The precipitation-strengthened nickel-iron-based high-temperature alloy pipe that has undergone hot extrusion treatment is subjected to high-temperature solution treatment. The specific process of the high-temperature solution treatment includes: heating the alloy pipe from room temperature to 220°C below the TiC phase precipitation temperature at a heating rate of 12°C / min, then keeping it warm for 4.5 hours, and water quenching after the end of the insulation. The alloy pipe after the high-temperature solution treatment is then cold-deformed and rolled on a pipe rolling mill, with a rolling deformation of 35%, to obtain a cold-rolled pipe;

[0066] Will Na 2 CO 3 , NaOH, sodium silicate, ethanol and water are prepared into a cleaning solution in a mass ratio of 4.3:5.1:5:4:60, and then the cold-rolled pipe is placed in a cleaning tank for circulation and degreasing. During the circulation and degreasing, the cleaning liquid temperature is 100°C and the cleaning time is 40 minutes. Then the cleaning liquid on the surface of the cold-rolled pipe is washed away, and then dried, and the cold-rolled pipe cleaning is completed. The cleaned pipe is subjected to low-temperature solid solution treatment. The low-temperature solid solution treatment process specifically includes: heating the cleaned cold-rolled pipe from room temperature at a heating rate of 10°C / min to 240°C below the TiC phase precipitation temperature, and then keeping it warm for 3.5 hours, and air cooling after the end of the insulation. After the low-temperature solid solution treatment, the alloy pipe is pressure straightened and the surface oxide scale is removed.

[0067] Figure 8 This is the low-power cross-sectional morphology of the precipitation-strengthened high-temperature alloy tube near the inner surface in Comparative Example 2. It can be seen that there are many abnormal precipitated phases in the inner surface crystals and at the grain boundaries. Fig. 9 This is the high-magnification morphology of the precipitated phase. Fig.10 is the EDS spectrum result of the corresponding precipitated phase, and the results show that the precipitated phase is TiC phase.

[0068] Test example

[0069] The conventional mechanical properties of the embodiments and comparative examples after high temperature solution treatment are shown in Table 1. The conventional mechanical properties of the embodiments and comparative examples after low temperature solution treatment are shown in Table 2.

[0070] Table 1

[0071] Yield Strength tensile strength Elongation Impact toughness Example 1 341MPa 695MPa 49.1％ <![CDATA[138J / cm 2 ]]> Example 2 420MPa 731MPa 48.6％ <![CDATA[146J / cm 2 ]]> Example 3 389MPa 705MPa 50.1％ <![CDATA[137J / cm 2 ]]> Example 4 407MPa 724MPa 47.1％ <![CDATA[150J / cm 2 ]]> Comparative Example 1 339MPa 681MPa 48.2％ <![CDATA[135J / cm 2 ]]> Comparative Example 2 416MPa 725MPa 50.2％ <![CDATA[141J / cm 2 ]]>

[0072] Table 2

[0073] Yield Strength tensile strength Elongation Impact toughness Example 1 639MPa 1028MPa 35.2％ <![CDATA[93J / cm 2 ]]> Example 2 620MPa 1079MPa 36.1％ <![CDATA[89J / cm 2 <!-- 6 -->]]> Example 3 631MPa 1031MPa 38.9％ <![CDATA[102J / cm 2 ]]> Example 4 642MPa 1082MPa 40.4％ <![CDATA[111J / cm 2 ]]> Comparative Example 1 490MPa 890MPa 20.1％ <![CDATA[53J / cm 2 ]]> Comparative Example 2 511MPa 902MPa 19.4％ <![CDATA[50J / cm 2 ]]>

[0074] It can be seen from Table 1 and Table 2 that the basic mechanical properties of the embodiment and the comparative alloy are similar in the high-temperature solid solution stage, but the mechanical properties of the comparative alloy are significantly reduced after the low-temperature solid solution, especially the plasticity and toughness are significantly reduced. This is because the precipitated TiC phase makes the grain boundary brittle, resulting in reduced plasticity and toughness. This shows that the alloy surface improvement method in the present invention is of great significance for eliminating the TiC phase aggregated near the surface and improving the plasticity and toughness of the alloy.

Claims

1. A method for preparing a precipitation-strengthened high-temperature alloy tube, characterized in that: include: High temperature solution treatment: heat the precipitation-strengthened nickel-iron-based high temperature alloy tube that has undergone hot extrusion treatment to 180-200°C below the TiC phase precipitation temperature, then keep it warm for 3.0-3.5 hours, and quickly cool it after the end of the warming period; wherein, the heating rate during heating is 12-15°C / min; Cold rolling process: cold rolling the precipitation-strengthened nickel-iron-based high-temperature alloy tube after high-temperature solid solution treatment to the target size to obtain a cold-rolled tube; wherein the rolling deformation of the cold rolling is 35%-40%; Surface cleaning process: degreasing the cold rolled tube, removing the cleaning fluid, and drying; Low-temperature solution treatment: heating the cold-rolled tube after surface cleaning to 260-280°C below the TiC phase precipitation temperature, then keeping it warm for 2.5-3.0 hours, and air cooling after the end of the insulation to obtain the precipitation-strengthened high-temperature alloy tube; wherein the heating rate during heating is 10-12°C / min.

2. The method for preparing a precipitation-strengthened high-temperature alloy tube according to claim 1, characterized in that: During high temperature solution treatment, water quenching is used for rapid cooling.

3. The method for preparing a precipitation-strengthened high-temperature alloy tube according to claim 1, characterized in that: The precipitation-strengthened nickel-iron-based high-temperature alloy pipe after high-temperature solution treatment has a yield strength of not less than 340MPa, a tensile strength of not less than 695MPa, a room temperature elongation of more than 47%, and an impact resistance of not less than 135J / cm 2 .

4. The method for preparing a precipitation-strengthened high-temperature alloy tube according to claim 1, characterized in that: The cleaning liquid used for degreasing is prepared from Na2CO3, NaOH, sodium silicate, ethanol and water, wherein the mass ratio of Na2CO3, NaOH, sodium silicate, ethanol and water is (3.0-4.5):(3.5-5.5):(2-6):(2-4):(30-60).

5. The method for preparing a precipitation-strengthened high-temperature alloy tube according to claim 4, characterized in that: During the degreasing process, the cleaning liquid temperature is 80-100°C and the cleaning time is 40-50 minutes.

6. The method for preparing a precipitation-strengthened high-temperature alloy tube according to claim 1, 4 or 5, characterized in that: The degreasing process uses cleaning fluid for circulating cleaning.

7. A method for preparing a precipitation-strengthened high-temperature alloy tube according to any one of claims 1 to 6, characterized in that: After the low-temperature solution treatment is completed, the pipe after the low-temperature solution treatment is pressure straightened and descaled.

8. A precipitation-strengthened high-temperature alloy pipe, characterized in that: The precipitation-strengthened high-temperature alloy tube is prepared by any one of the preparation methods of claims 1-7.

9. The precipitation-strengthened high-temperature alloy tube according to claim 8, characterized in that: In terms of mass percentage, the components of the precipitation-strengthened high-temperature alloy pipe include: Ti: 1.0% to 4.5%, Al: 1.0% to 4.5%, Ta: ≤0.1%, Co: 1.0% to 3.4%, W: 0.1% to 1.2%, Si: 0.02% to 1.3%, C: 0.09% to 1.0%, Cr: 12% to 24%, Fe: 20% to 34%, Pb: 0 to 0.005%, Bi: 0.0001% to 0.0005%, Se: 0.002% to 0.005%, and the balance is Ni.

10. The precipitation-strengthened high-temperature alloy tube according to claim 8, characterized in that: The precipitation-strengthened high-temperature alloy pipe has a yield strength of not less than 620 MPa, a tensile strength of not less than 1025 MPa, a room temperature elongation of more than 35%, and an impact resistance of not less than 89 J / cm 2 .

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