Monel alloy hot extrusion pipe and preparation method thereof

Abstract

The invention belongs to the technical field of corrosion-resistant alloy hot extrusion machining, and discloses a Monel alloy hot extrusion pipe and a preparation method thereof.The preparation method comprises the steps that blank pretreatment is conducted, specifically, the surface of a blank is machined to the required specification; heating in an annular furnace: heating the pretreated blank in the annular furnace, and sequentially carrying out preheating, heating and soaking treatment; primary induction furnace heating; carrying out first induction furnace heating on the blank heated by the annular furnace; the inner surface and the outer surface of the blank heated by the induction furnace for the first time are coated with a proper amount of uniform glass powder to serve as a lubricating agent, and broaching is conducted to the target specification; heating the blank by a secondary induction furnace; carrying out secondary induction furnace heating on the broached blank; and extrusion: coating a proper amount of uniform glass powder on the inner surface and the outer surface of the blank heated by the induction furnace for the second time as a lubricant, extruding by adopting an extrusion process, and cooling by water. The Monel 400 alloy hot extrusion seamless pipe prepared by the method is good in surface quality, uniform in structure and excellent in performance.

Description

Technical Field

[0001] The present invention relates to the technical field of hot extrusion processing of corrosion-resistant alloys, and particularly to a Monel alloy hot-extruded pipe and a preparation method thereof. Background Art

[0002] Monel alloy is a typical nickel-copper corrosion-resistant alloy. This alloy was discovered by the International Nickel Company in 1906 and is widely used in fields such as marine, petroleum, and microelectronics. Compared with typical stainless steels and other corrosion-resistant alloys, it has incomparable corrosion resistance in media such as organic acids, seawater, and hydrogen chloride.

[0003] Monel 400 alloy is a single-phase austenitic alloy of Ni-Cu solid solution, having excellent corrosion resistance and medium-temperature strength. This alloy generally does not produce stress corrosion cracks, has good cutting performance, and has extremely excellent corrosion resistance in fluorine gas, hydrochloric acid, sulfuric acid, hydrofluoric acid, and their derivatives. At the same time, it is also resistant to the corrosion of neutral solutions, hot concentrated alkali solutions, water, seawater, atmosphere, organic compounds, etc. It can be used for seamless water pipes, steam pipes, seawater exchangers and evaporators in power plants, pump shafts of equipment using seawater and hydrochloric acid, equipment for uranium extraction and isotope separation, reaction kettles, etc.

[0004] At present, Monel 400 alloy seamless pipes are generally prepared by cold working methods. However, the cold working deformation resistance is large. When using this processing method to prepare pipes, multiple cold working processes are usually required, and softening annealing is required after each cold working to obtain pipes with uniform structure and excellent performance. While during hot working, the deformation resistance is small, and large deformation can be achieved in one heat treatment, thereby obtaining pipes with uniform structure and excellent performance. At the same time, due to the narrow hot working temperature range of Monel 400 alloy, surface cracking is likely to occur during the hot working process, and it is difficult to achieve uniform structure. Therefore, there is an urgent need to develop a new preparation method to obtain Monel 400 alloy seamless pipes with good surface quality, uniform structure, and excellent performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a Monel alloy hot-extruded pipe and a preparation method thereof for extruding and preparing Monel 400 alloy hot-extruded seamless pipes with uniform structure and excellent performance. To achieve the above purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a preparation method of a Monel alloy hot-extruded pipe, and the method includes the following steps:

[0007] Blank pretreatment: Processing the surface of the blank to the required specifications;

[0008] Ring furnace heating: Heat the pre-treated blank in a ring furnace, successively through preheating, heating, and soaking heat treatment;

[0009] Primary induction furnace heating: Heat the blank after ring furnace heating in the primary induction furnace;

[0010] Hole expansion: Coat the inner and outer surfaces of the blank after primary induction furnace heating with an appropriate amount of evenly distributed glass powder as a lubricant, and then expand the hole to the target specification;

[0011] Secondary induction furnace heating of the blank: Heat the blank after hole expansion in the secondary induction furnace;

[0012] Extrusion: Coat the inner and outer surfaces of the blank after secondary induction furnace heating with an appropriate amount of evenly distributed glass powder as a lubricant, and then extrude using an extrusion process and cool with water.

[0013] Furthermore, the required specifications include: surface roughness Ra ≤ 3.2 mm, roundness ≤ 0.025 mm, and drilling diameter of Φ35 - 55 mm.

[0014] Furthermore, the soaking heat treatment regime in the ring furnace heating includes: heating temperature of 980 - 1050 °C, and holding time of 2 - 4 h.

[0015] Furthermore, the primary induction furnace heating regime includes: heating temperature of 1020 - 1100 °C, and holding time of 2 - 5 min.

[0016] Furthermore, expand the hole to a diameter of Φ103 - 113 mm.

[0017] Furthermore, the secondary induction furnace heating regime includes: heating temperature of 1020 - 1100 °C, and holding time of 2 - 5 min.

[0018] Furthermore, the extrusion process includes: extruding using an extruder, with an inner diameter of the extrusion die of 110.8 ± 0.2 mm, a core rod diameter of Φ89 ± 0.2 mm, and an extrusion speed of 100 - 160 mm / s.

[0019] The present invention also provides a Monel alloy hot-extruded pipe. In terms of mass percentage content, the components and their contents of the Monel alloy are as follows:

[0020] C ≤ 0.3%; Mn ≤ 2.0%; S ≤ 0.024%; Si ≤ 0.5%; Ni ≥ 63.0%; Cu: 28.0 - 34.0%; Fe ≤ 2.5%.

[0021] Furthermore, the room temperature tensile properties of the Monel alloy hot-extruded pipe include:

[0022] The tensile strength Rm ≥ 500 MPa, the proof strength Rp0.2 ≥ 200 MPa, and the elongation at break δ5 ≥ 40%.

[0023] Furthermore, the grain size of the Monel alloy hot-extruded pipe is finer than grade 8.

[0024] The technical effects and advantages of the present invention:

[0025] Compared with the prior art in which seamless pipes of Monel 400 alloy are prepared by cold working, the present invention uses a hot working method, specifically a hot extrusion method. By controlling the surface quality of the billet, the billet heating system, the hole expansion deformation of the billet, the reheating of the deformed billet, and the extrusion process parameters, etc., seamless Monel 400 alloy hot-extruded pipes with good surface quality, uniform structure, and excellent performance are prepared.

[0026] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained through the structures pointed out in the specification and

[0027] the drawings. Brief Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0029] Figure 1 It is a flow chart of the preparation method of a Monel alloy hot-extruded pipe of the present invention;

[0030] Figure 2 It is a metallographic structure picture (100x) of the Monel alloy hot-extruded pipe prepared in Example 1 of the present invention;

[0031] Figure 3 It is a metallographic structure picture (100x) of the Monel alloy hot-extruded pipe prepared in Example 2 of the present invention;

[0032] Figure 4 It is a metallographic structure picture (100x) of the Monel alloy hot-extruded pipe prepared in Example 3 of the present invention;

[0033] Figure 5 It is a picture of the appearance morphology of the pipe in Comparative Example 1 of the present invention;

[0034] Figure 6Metallographic structure picture (100x) of the Monel alloy hot extrusion pipe prepared in Comparative Example 2 of the present invention;

[0035] Figure 7 Appearance morphology diagram of the pipe in Comparative Example 3 of the present invention. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] The flowchart shown in the accompanying drawings is only an exemplary illustration and does not necessarily include all the steps. For example, some steps can be decomposed, and some steps can be combined or partially combined. Therefore, the actual execution order may be changed according to the actual situation.

[0038] The terms "first", "second", etc. in the specification and claims of this application and the above accompanying drawings are used to distinguish similar objects and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of this application described here can be implemented in an order other than those illustrated or described here.

[0039] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or sub-modules does not necessarily have to be limited to those clearly listed steps or sub-modules, but may include other steps or sub-modules that are not clearly listed or are inherent to these processes, methods, products, or devices.

[0040] To solve the deficiencies of the prior art, the present invention discloses a Monel alloy hot extrusion pipe and a preparation method thereof. Figure 1 Flowchart of a preparation method of a Monel alloy hot extrusion pipe of the present invention, as Figure 1 shown, mainly includes the following steps:

[0041] Step S1, blank pretreatment: Through processes such as surface turning and drilling, the surface of the blank is processed to the required specifications, where the surface roughness Ra ≤ 3.2 mm, the roundness ≤ 0.025 mm, and the drilling diameter is Φ35 - 55 mm.

[0042] Step S2, Ring Furnace Heating: Heat the pre-treated blank in a ring furnace, successively through preheating, heating, and soaking heat treatment; among them, the soaking section regime includes: heating temperature is 980 - 1050 °C, and soaking time is 2 - 4 h.

[0043] Step S3, Primary Induction Furnace Heating: Heat the blank after ring furnace heating in a primary induction furnace, and the heating regime includes: heating temperature is 1020 - 1100 °C, and soaking time is 2 - 5 min.

[0044] Step S4, Reaming: Coat the inner and outer surfaces of the blank after the first induction furnace heating with an appropriate amount of evenly distributed glass powder as a lubricant, and ream to a diameter of Φ103 - 113 mm.

[0045] Step S5, Secondary Induction Furnace Heating: Heat the reamed blank in a secondary induction furnace, and the heating regime includes: heating temperature is 1020 - 1100 °C, and soaking time is 2 - 5 min.

[0046] Step S6, Extrusion: Extrude the blank after the second induction furnace heating using an extruder. The inner diameter of the extrusion die is 110.8 ± 0.2 mm, the core rod diameter is Φ89 ± 0.2 mm, the extrusion speed is 100 - 160 mm / s, coat the inner and outer surfaces with an appropriate amount of evenly distributed glass powder as a lubricant, and cool with water after extrusion.

[0047] The present invention also discloses a Monel alloy hot-extruded pipe. The Monel alloy hot-extruded pipe, in terms of mass percentage content, has the following components and contents:

[0048] C ≤ 0.3%; Mn ≤ 2.0%; S ≤ 0.024%; Si ≤ 0.5%; Ni ≥ 63.0%; Cu: 28.0 - 34.0%; Fe ≤ 2.5%.

[0049] Furthermore, the room temperature tensile properties of the Monel alloy hot-extruded pipe include:

[0050] Tensile strength Rm ≥ 500 MPa, yield strength Rp0.2 ≥ 200 MPa, elongation at break δ5 ≥ 40%.

[0051] Furthermore, the grain size of the Monel alloy hot-extruded pipe is finer than grade 8.

[0052] Example 1:

[0053] The preparation of the Monel 400 alloy hot-extruded pipe in Example 1 of the present invention is carried out according to the following method:

[0054] Step S1. Blank pre-treatment: Through processes such as surface turning and drilling, the surface of the blank is processed to the required specifications. Among them, the surface roughness Ra ≤ 3.2 mm, the roundness ≤ 0.025 mm, and the drilling diameter is Φ45 mm.

[0055] Step S2. Ring furnace heating: The pre-treated blank is heated in a ring furnace, successively through preheating, heating, and soaking. Among them, the soaking section regime includes: the heating temperature is 990 °C, and the holding time is: 2 h 15 min.

[0056] Step S3. Primary induction furnace heating: The blank heated in the ring furnace is subjected to primary induction furnace heating. The heating regime includes: the heating temperature is 1060 °C, and the holding time is: 2 min 35 s.

[0057] Step S4. Reaming: Appropriate and uniform glass powder is coated on the inner and outer surfaces of the blank after the first induction furnace heating as a lubricant, and the blank is reamed to a diameter of Φ108 mm.

[0058] Step S5. Secondary induction furnace heating: The reamed blank is subjected to secondary induction furnace heating. The heating regime includes: the heating temperature is 1040 °C, and the holding time is: 4 min 40 s.

[0059] Step S6. Extrusion: The blank after the second induction furnace heating is extruded using a 45 MN extruder. The inner diameter of the extrusion die is 110.8 ± 0.2 mm, the core rod diameter is Φ89 ± 0.2 mm, the extrusion speed is 120 - 140 mm / s, appropriate and uniform glass powder is coated on the inner and outer surfaces as a lubricant, and seamless tubes with a specification of Φ108 * 10 mm are extruded and water-cooled after extrusion.

[0060] In terms of mass percentage, for the Monel alloy hot-extruded tube of Example 1 of the present invention, its main components and contents are shown in Table 1 below:

[0061] Table 1 Main components and contents of the Monel alloy hot-extruded tube of Example 1

[0062] C Mn S Si Ni Cu Fe 0.037％ 0.56％ 0.0008％ 0.11％ 67.49％ 31.65％ 0.15％

[0063] The metallographic structure picture of the Monel alloy hot-extruded tube prepared in Example 1 of the present invention is as shown in the appendix Figure 2 and the average grain size rating (GB / T 6394-2002 "Method for Determining the Average Grain Size of Metals") is 9.5 levels.

[0064] Example 2:

[0065] The Monel 400 alloy hot-extruded tube is prepared according to the following method in Example 2 of the present invention:

[0066] Step S1. Blank pretreatment: Through processes such as surface turning and drilling, the surface of the blank is processed to the required specifications. Among them, the surface roughness Ra ≤ 3.2 mm, the roundness ≤ 0.025 mm, and the drilling diameter is Φ45 mm.

[0067] Step S2. Ring furnace heating: The pretreated blank is heated in a ring furnace, successively passing through preheating, heating, and soaking. Among them, the soaking section regime includes: the heating temperature is 1030 °C, and the holding time is: 2 h 30 min.

[0068] Step S3. Primary induction furnace heating: The blank heated in the ring furnace is subjected to primary induction furnace heating. The heating regime includes: the heating temperature is 1030 °C, and the holding time is: 4 min 30 s.

[0069] Step S4. Reaming: An appropriate amount of uniform glass powder is coated on the inner and outer surfaces of the blank after the first induction furnace heating as a lubricant, and the blank is reamed to a diameter of Φ108 mm.

[0070] Step S5. Secondary induction furnace heating: The reamed blank is subjected to secondary induction furnace heating. The heating regime includes: the heating temperature is 1090 °C, and the holding time is: 4 min 15 s.

[0071] Step S6. Extrusion: The blank after the second induction furnace heating is extruded using a 45 MN extruder. The inner diameter of the extrusion die is 110.8 ± 0.2 mm, the core rod diameter is Φ89 ± 0.2 mm, the extrusion speed is 130 - 155 mm / s, and an appropriate amount of uniform glass powder is coated on the inner and outer surfaces

[0072] as a lubricant to extrude seamless tubes with a specification of Φ108 * 10 mm, and water cooling is carried out after extrusion.

[0073] In terms of mass percentage, for the Monel alloy hot - extruded tubes in Example 2 of the present invention, the main components and their contents are shown in Table 2 below:

[0074] Table 2 Main components and contents of the Monel alloy hot - extruded tubes in Example 2

[0075] C Mn S Si Ni Cu Fe 0.032％ 0.61％ 0.0005％ 0.12％ 67.4％ 31.71％ 0.12％

[0076] The metallographic structure picture of the Monel alloy hot - extruded tubes prepared in Example 2 of the present invention is as shown in the appendix Figure 3 and the average grain size rating (GB / T6394 - 2002 "Method for Determining the Average Grain Size of Metals") is 10.

[0077] Example 3:

[0078] The Monel 400 alloy hot - extruded tubes are prepared in Example 3 of the present invention according to the following method:

[0079] Step S1. Blank pretreatment: Through processes such as surface turning and drilling, the surface of the blank is processed to the required specifications. Among them, the surface roughness Ra ≤ 3.2 mm, the roundness ≤ 0.025 mm, and the drilling diameter is Φ45 mm.

[0080] Step S2. Ring furnace heating: The pretreated blank is heated in a ring furnace, successively through preheating, heating, and soaking. Among them, the soaking section regime includes: the heating temperature is 1020 °C, and the holding time is: 2 h 45 min.

[0081] Step S3. Primary induction furnace heating: The blank heated in the ring furnace is subjected to primary induction furnace heating. The heating regime includes: the heating temperature is 1050 °C, and the holding time is: 3 min 10 s.

[0082] Step S4. Reaming: An appropriate amount of uniform glass powder is coated on the inner and outer surfaces of the blank after the first induction furnace heating as a lubricant, and the blank is reamed to a diameter of Φ110 mm.

[0083] Step S5. Secondary induction furnace heating: The reamed blank is subjected to secondary induction furnace heating. The heating regime includes: the heating temperature is 1070 °C, and the holding time is: 2 min 50 s.

[0084] Step S6. Extrusion: The blank after the second induction furnace heating is extruded using a 45 MN extrusion press. The inner diameter of the extrusion die is 110.8 ± 0.2 mm, the core rod diameter is Φ89 ± 0.2 mm, the extrusion speed is 125 - 150 mm / s, an appropriate amount of uniform glass powder is coated on the inner and outer surfaces as a lubricant, and seamless tubes with a specification of Φ108 * 10 mm are prepared by extrusion. After extrusion, water cooling is carried out.

[0085] In terms of mass percentage, for the Monel alloy hot-extruded tube in Example 3 of the present invention, its main components and contents are shown in Table 1 below:

[0086] Table 3 Main components and contents of the Monel alloy hot-extruded tube in Example 3

[0087] C Mn S Si Ni Cu Fe 0.039％ 0.58％ 0.0006％ 0.14％ 67.12％ 31.91％ 0.21％

[0088] The metallographic structure picture of the Monel alloy hot-extruded tube prepared in Example 3 of the present invention is as shown in the appendix Figure 4 and the average grain size rating (GB / T 6394-2002 "Method for Determining the Average Grain Size of Metals") is 10 levels.

[0089] Comparative Example 1:

[0090] With Example 1 as a reference, when other conditions remain unchanged, in Step S1 of Comparative Example 1 of the present invention, the surface roughness Ra of the blank is > 3.2 mm, and the surface quality of the extruded product is poor. In severe cases, surface cracking and scrapping occur. A typical surface appearance is as shown in Figure 5 shown.

[0091] Comparative Example 2:

[0092] With Example 1 as a reference, when other conditions remain unchanged, in Step S2 of Comparative Example 2 of the present invention, the heating temperature of the blank in the soaking section of the annular furnace is higher than 1080 °C, and abnormal grain growth of the blank will occur. The extruded pipes will have abnormal structures such as coarse grains and mixed grains. A typical abnormal metallographic structure is as shown in Figure 6 shown.

[0093] Comparative Example 3:

[0094] With Example 1 as a reference, when other conditions remain unchanged, the extrusion speed of Comparative Example 3 of the present invention is too slow (slower than 90 mm / s). Due to temperature drop, abnormal situations such as "jamming" during extrusion and inability to extrude pipes may occur; or the extrusion speed is too fast (faster than 170 mm / s). Due to the large temperature rise caused by deformation, local instability may occur and cracks may be generated, as shown in Figure 7 shown.

[0095] Performance testing:

[0096] After specimens were taken from the pipes prepared in the above examples, a room temperature tensile test was carried out; the specimen preparation was carried out in accordance with the standard of GB / T 2975-1998 "Sampling positions and specimen preparation for mechanical property tests of steels and steel products"; the tensile test was detected in accordance with the standard of GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Method of test at room temperature". The test results are shown in Table 1 below:

[0097] Table 1 Tensile property test results of the hot-extruded pipes prepared in the examples of the present invention

[0098] <![CDATA[Yield strength R p0.2 / MPa]]> Tensile strength Rm / MPa Elongation after fracture δ5 / % Example 1 226 532 46.0 Example 2 241 544 47.0 Example 3 239 539 46.5

[0099] As can be seen from Table 1, the Monel 400 alloy hot-extruded pipes prepared by the method of the present invention have excellent properties, with a yield strength > 200 MPa, a tensile strength > 500 MPa, and an elongation after fracture > 40%.

[0100] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features.

[0101] Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a monel alloy hot extrusion pipe, characterized in that: The method comprises the following steps: Blank pretreatment: Process the blank surface to the required specifications; Ring furnace heating: The pretreated blank is heated in a ring furnace, and is preheated, heated and soaked in sequence; Primary induction furnace heating: the billet heated in the ring furnace is heated in the first induction furnace; Hole expansion: After the first induction furnace heating, the inner and outer surfaces of the blank are coated with an appropriate amount of uniform glass powder as a lubricant, and then the hole is expanded to the target specification; The second induction furnace heats the blank; the blank after hole expansion is heated by the second induction furnace; Extrusion: After the second induction furnace heating, the inner and outer surfaces of the blank are coated with an appropriate amount of uniform glass powder as a lubricant, and then extruded by the extrusion process and then water-cooled.

2. The method for preparing a monel alloy hot extrusion pipe according to claim 1, characterized in that: The required specifications include: surface roughness Ra≤3.2mm, ovality≤0.025mm, and drilling diameter of Φ35~55mm.

3. The method for preparing a monel alloy hot extrusion pipe according to claim 1, characterized in that: The heating soaking section system of the annular furnace includes: a heating temperature of 980 to 1050° C. and a heat preservation time of 2 to 4 hours.

4. The method for preparing a monel alloy hot extrusion pipe according to claim 2, characterized in that: The primary induction furnace heating system includes: a heating temperature of 1020-1100° C. and a heat preservation time of 2-5 minutes.

5. The method for preparing a monel alloy hot extrusion pipe according to claim 1, characterized in that: The hole is expanded to a diameter of Φ103-113 mm.

6. The method for preparing a monel alloy hot extrusion pipe according to claim 1, characterized in that: The secondary induction furnace heating system includes: heating temperature of 1020-1100° C., and insulation time of 2-5 minutes.

7. The method for preparing a monel alloy hot extrusion pipe according to claim 1, characterized in that: The extrusion process comprises: extruding by an extruder, the inner diameter of the extrusion die is 110.8±0.2 mm, the diameter of the core rod is Φ89±0.2 mm, and the extrusion speed is 100-160 mm / s.

8. A monel alloy hot extrusion pipe, prepared by the method according to any one of claims 1 to 7, characterized in that: The monel alloy is measured by mass percentage, and its components and contents are as follows: C≤0.3%; Mn≤2.0%; S≤0.024%; Si≤0.5%; Ni≥63.0%; Cu: 28.0~34.0%; Fe≤2.5%.

9. The monel alloy hot extrusion pipe according to claim 8, characterized in that: The room temperature tensile properties of the monel alloy hot extruded pipe include: Tensile strength Rm≥500MPa, tensile strength Rp0.2≥200MPa, elongation δ5≥40%.

10. The monel alloy hot extrusion pipe according to claim 8, characterized in that: The grain size of the monel alloy hot extruded pipe is finer than grade 8.

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