Preparation method of high-yield Ni-Fe-based high-temperature alloy bar billet for ultra-supercritical thermal power generating unit

Abstract

The invention discloses a preparation method of a Ni-Fe-based high-temperature alloy bar billet for a high-yield ultra-supercritical thermal power generating unit. The Ni-Fe-based high-temperature alloy bar billet comprises the following materials: 0.045-0.055% of C, 18.0-20.0% of Cr, 0.4-0.6% of Mo and 0.2-0.4% of W; the high-temperature alloy comprises the following components in percentage by weight: 0.002 to 0.005 percent of B, 1.5 to 2.5 percent of Co, 25.0 to 27.0 percent of Fe, 1.9 to 2.1 percent of Al, 2.0 to 2.2 percent of Ti and the balance of Ni. The preparation method comprises the following steps: S1, obtaining a uniform and compact high-temperature alloy cast ingot through vacuum induction and vacuum self consumption; s2, cogging is conducted, specifically, the high-temperature alloy cast ingot obtained in the S1 is put into a heating furnace to be heated, the temperature is slowly increased to 1100 DEG C, the heat preservation time is longer than or equal to 120 h after the cast ingot reaches the temperature, cogging forging is conducted, the initial forging temperature is larger than or equal to 950 DEG C, and the final forging temperature is larger than or equal to 850 DEG C; according to the method, the Ni-Fe-based high-temperature alloy bar billet is prepared in the mode of double vacuum smelting and fast forging forming, the Ni-Fe-based high-temperature alloy bar billet capable of being directly used for supercritical thermal power generating unit parts is finally obtained through the deformation process of multi-heating-number small deformation, and the forging yield is not smaller than 85%.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal processing, in particular to a method for preparing a Ni-Fe-based high-temperature alloy rod blank for an ultra-supercritical thermal power unit with a high yield rate. Background Art

[0002] Ni-Fe-based high-temperature alloys are preferred as candidate materials for ultra-supercritical power plants due to their excellent high-temperature structural stability, high-temperature tensile properties, high-temperature oxidation resistance and heat corrosion resistance. However, due to the extremely high raw material and production costs, their promotion and application have been hindered. The cost of raw materials cannot be controlled due to market influence, and reducing costs through technical optimization in production is an effective way to promote the application of materials. As the preparation of ultra-supercritical power plant component blanks, improving the yield rate is the first problem to be solved. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing a Ni-Fe based high temperature alloy rod for an ultra-supercritical thermal power unit with a high yield rate, so as to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a method for preparing a Ni-Fe-based high-temperature alloy bar billet for an ultra-supercritical thermal power unit with a high yield rate, comprising the following materials: C: 0.045-0.055, Cr: 18.0-20.0, Mo: 0.4-0.6, W: 0.2-0.4; B: 0.002-0.005, Co: 1.5-2.5, Fe: 25.0-27.0, Al: 1.9-2.1, Ti: 2.0-2.2, and the rest is Ni, the method comprising the following steps:

[0005] S1. Vacuum induction + vacuum self-consumption to obtain uniform and dense high-temperature alloy ingots;

[0006] S2, open the blank, put the high temperature alloy ingot obtained in S1 into a heating furnace for heating, slowly raise the temperature to 1100°C, keep the ingot warm for ≥120h, and perform open forging, the starting forging temperature is ≥950°C, and the final forging temperature is ≥850°C;

[0007] S3, forming, subjecting the ingot obtained in S2 to 2-4 fire forming forging, the forging heating temperature is 1050℃-1100℃, and the deformation amount of each forging is 30%-45%;

[0008] S4, rounding and straightening, the intermediate billet obtained in S3 is rounded and straightened by one rounding, the rounding and straightening heating temperature is 1000°C-1050°C, and the deformation amount of the rounding fire is 2-7%.

[0009] S5, sawing and peeling, sawing the irregular ends of the forged rod obtained in S4, peeling the surface after sawing, and the peeling amount is controlled within the range of 3-5mm; after sawing and peeling, a Ni-Fe-based high-temperature alloy rod blank that can be directly used for supercritical thermal power unit parts is obtained.

[0010] Preferably, the specification of the high-temperature alloy bar billet is Φ200mm-Φ500mm.

[0011] Preferably, the blank forging in S2 adopts continuous re-furnace forging, radial upsetting and drawing, and the blanking fire deformation is 15%-35%.

[0012] Preferably, the forming stage in S3 is divided into 2-4 fires, 2 fires adopt radial upsetting and drawing method, the heating temperature is 1080℃-1100℃, 3-4 fires adopt double V drawing forming, double V is divided into 3 passes of drawing, the deformation of the 1st and 2nd passes are 15-20%, the deformation of the 3rd pass is 3-7%, and the heating temperature is 1050℃-1080℃.

[0013] Preferably, in said S3, the reduction rate of 2-3 fire forging is 30mm / s-50mm / s, and the circle-circle deformation method is adopted in 4-5 fire forging.

[0014] Preferably, the rounding anvil in S4 is a spring anvil or a U-shaped anvil with a tolerance range of (+2, -1) mm; after rounding, the billet is air-cooled and the straightness of the billet satisfies ≤2 mm / m.

[0015] Preferably, the peeling diameter range of the forged bar in S5 is controlled within the range of (+1, -1) mm, and the resulting Ni-Fe-based high-temperature alloy bar blank can be directly used for supercritical thermal power unit parts, and the forging finished product rate is not less than 85%.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention prepares Ni-Fe-based high-temperature alloy rod blanks by the method of "double vacuum smelting + fast forging", and reduces the amount of peeling by controlling the two-fire "double V" deformation and small deformation process in the forming stage, significantly improves the yield to reduce costs, and obtains Ni-Fe-based high-temperature alloy rod blanks with uniform carbide distribution and better grain size. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The carbide distribution and high-magnification structure of a typical billet;

[0018] Figure 2 The figure is a comparison of the yield rate of the rod blanks. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0020] See also Figure 1-Figure 2 , the present invention provides a technical solution:

[0021] Example 1

[0022] A method for preparing a Ni-Fe-based high-temperature alloy bar billet for an ultra-supercritical thermal power unit with a high yield rate includes the following materials: C: 0.05, Cr: 19.0, Mo: 0.5, W: 0.3; B: 0.0035, Co: 2.0, Fe: 26.0, Al: 2.0, Ti: 2.1, and the rest is Ni, and includes the following steps:

[0023] S1. Vacuum induction + vacuum self-consumption to obtain uniform and dense high-temperature alloy ingots;

[0024] S2, open the blank, put the high temperature alloy ingot obtained in S1 into a heating furnace for heating, slowly raise the temperature to 1100°C, keep the ingot warm for 120h, and then forge the blank, the starting forging temperature is ≥950°C, and the final forging temperature is ≥850°C;

[0025] S3, forming, the ingot obtained in S2 is subjected to 4-fire forming forging, the forging heating temperature is 1050°C-1100°C, and the deformation amount of each forging is 30%-45%;

[0026] S4, rounding and straightening, the intermediate billet obtained in S3 is rounded and straightened by one rounding, the rounding and straightening heating temperature is 1000°C, and the rounding fire deformation is 5%.

[0027] S5, sawing and peeling, sawing the irregular ends of the forged bars obtained in S4, peeling the surface after sawing, and controlling the peeling amount to 4mm. After sawing and peeling, the Ni-Fe-based high-temperature alloy bar blank that can be directly used for supercritical thermal power unit parts is obtained.

[0028] Among them, the specification of high-temperature alloy rod billet is Φ213mm.

[0029] Among them, the billet forging in S2 adopts continuous re-forging, radial upsetting and drawing, and the deformation of the billet forging fire is 25%.

[0030] Among them, the forming stage in S3 is divided into 4 fires. The first 2 fires adopt radial upsetting and drawing methods with a heating temperature of 1080℃. The 3rd and 4th fires adopt double V drawing forming with a heating temperature of 1050℃.

[0031] Among them, the reduction rate of 2 and 3 fire forging is 40mm / s, and the circle-circle deformation method is adopted for 4 and 5 fire forging.

[0032] Among them, the rounding anvil type in S4 is a spring anvil or a U-shaped anvil, and the tolerance range is (+2,-1) mm. After rounding, the billet is air-cooled and the straightness of the billet meets ≤2mm / m.

[0033] The diameter range of the rod billet peeling in S5 is controlled within the range of (+1, -1) mm, and the Ni-Fe-based high-temperature alloy rod billet that can be directly used for supercritical thermal power unit parts is obtained. The forging yield rate is 75%, and the grain size of the rod billet as a whole is rated as Grade 4 according to GB / T 6394 standard, and the carbide is rated as Grade 5 according to GB / T14999.6 standard.

[0034] Example 2

[0035] A method for preparing a Ni-Fe-based high-temperature alloy bar billet for an ultra-supercritical thermal power unit with a high yield rate includes the following materials: C: 0.05, Cr: 19.0, Mo: 0.5, W: 0.3; B: 0.0035, Co: 2.0, Fe: 26.0, Al: 2.0, Ti: 2.1, and the rest is Ni, and includes the following steps:

[0036] S1. Vacuum induction + vacuum self-consumption to obtain uniform and dense high-temperature alloy ingots;

[0037] S2, open the blank, put the high temperature alloy ingot obtained in S1 into a heating furnace for heating, slowly raise the temperature to 1100°C, keep the ingot warm for 120h, and then forge the blank, the starting forging temperature is ≥950°C, and the final forging temperature is ≥850°C;

[0038] S3, forming, the ingot obtained in S2 is subjected to 4-fire forming forging, the forging heating temperature is 1050°C, and the deformation amount of each forging is 30%-45%;

[0039] S4, rounding and straightening, the intermediate billet obtained in S3 is rounded and straightened by one rounding, the rounding and straightening heating temperature is 1000°C, and the rounding fire deformation is 5%.

[0040] S5, sawing and peeling, sawing the irregular ends of the forged bars obtained in S4, peeling the surface after sawing, and controlling the peeling amount to 4mm. After sawing and peeling, the Ni-Fe-based high-temperature alloy bar blank that can be directly used for supercritical thermal power unit parts is obtained.

[0041] Among them, the specification of high-temperature alloy rod billet is Φ213mm.

[0042] Among them, the billet forging in S2 adopts continuous re-forging, radial upsetting and drawing, and the deformation of the billet forging fire is 25%.

[0043] Among them, the forming stage in S3 is divided into 4 fires. The first 2 fires adopt radial upsetting and drawing methods with a heating temperature of 1080℃. The 3rd and 4th fires adopt double V drawing forming. The double V is divided into 3 passes of drawing. The deformation of the 1st and 2nd passes is 18%, the deformation of the 3rd pass is 5%, and the heating temperature is 1050℃℃.

[0044] Among them, the reduction rate of 2 and 3 fire forging is 40mm / s, and the circle-circle deformation method is adopted for 4 and 5 fire forging.

[0045] Among them, the rounding anvil type in S4 is a spring anvil or a U-shaped anvil, and the tolerance range is (+2,-1) mm. After rounding, the billet is air-cooled and the straightness of the billet meets ≤2mm / m.

[0046] The diameter range of the rod blank peeling in S5 is controlled within the range of (+1, -1) mm, and the Ni-Fe-based high-temperature alloy rod blank that can be directly used for supercritical thermal power unit parts is obtained. The forging yield rate is not less than 85%, and the grain size of the rod blank as a whole is rated as grade 8 according to GB / T6394 standard, and the carbide is rated as grade 2 according to GB / T14999.6 standard.

[0047] Comparative Example 1 and Example 2: In Example 2, the steps of the present invention are strictly followed to prepare Ni-Fe-based high-temperature alloy rod billets for ultra-supercritical thermal power units with high yield, while in Example 1, the double V process deformation amount is not strictly controlled.

[0048] Experimental results: The carbide distribution of the Ni-Fe-based high-temperature alloy bar blank finally obtained in Example 2 is more uniform and the grain size meets the requirements, and the yield rate reaches 85%. The carbide distribution uniformity of the Ni-Fe-based high-temperature alloy bar blank finally obtained in Example 1 is not enough and its grain size does not meet the requirements, and the yield rate is 75%.

[0049] Conclusion: The present invention prepares Ni-Fe-based high-temperature alloy rod blanks by double vacuum smelting + rapid forging, and finally obtains Ni-Fe-based high-temperature alloy rod blanks with high yield, uniform carbide distribution and grain size meeting the requirements by controlling the deformation process in the double V process forming stage.

[0050] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a Ni-Fe-based high-temperature alloy bar billet for an ultra-supercritical thermal power unit with a high yield rate, comprising the following materials: C: 0.045-0.055, Cr: 18.0-20.0, Mo: 0.4-0.6, W: 0.2-0.4; B: 0.002-0.005, Co: 1.5-2.5, Fe: 25.0-27.0, Al: 1.9-2.1, Ti: 2.0-2.2, and the rest is Ni, characterized in that: The method comprises the following steps: S1. Vacuum induction + vacuum self-consumption to obtain uniform and dense high-temperature alloy ingots; S2, open the blank, put the high temperature alloy ingot obtained in S1 into a heating furnace for heating, slowly raise the temperature to 1100°C, keep the ingot warm for ≥120h, and perform open forging, the starting forging temperature is ≥950°C, and the final forging temperature is ≥850°C; S3, forming, subjecting the ingot obtained in S2 to 2-4 fire forming forging, the forging heating temperature is 1050℃-1100℃, and the deformation amount of each forging is 30%-45%; S4, rounding and straightening, the intermediate billet obtained in S3 is rounded and straightened by one rounding, the rounding and straightening heating temperature is 1000°C-1050°C, and the deformation amount of the rounding fire is 2-7%. S5, sawing and peeling, sawing the irregular ends of the forged rod obtained in S4, peeling the surface after sawing, and the peeling amount is controlled within the range of 3-5mm; after sawing and peeling, a Ni-Fe-based high-temperature alloy rod blank that can be directly used for supercritical thermal power unit parts is obtained.

2. The method for preparing a Ni-Fe-based high-temperature alloy bar billet for an ultra-supercritical thermal power unit with a high yield rate according to claim 1, characterized in that: The specifications of the high-temperature alloy bar blank are Φ200mm-Φ500mm.

3. The method for preparing a Ni-Fe-based high-temperature alloy bar billet for an ultra-supercritical thermal power unit with a high yield rate according to claim 1, characterized in that: The blank forging in S2 adopts continuous re-furnace forging, radial upsetting and drawing, and the blanking fire deformation is 15%-35%.

4. The method for preparing a Ni-Fe-based high-temperature alloy bar billet for an ultra-supercritical thermal power unit with a high yield rate according to claim 1, characterized in that: The forming stage in S3 is divided into 2-4 fires. The 2nd fire adopts radial upsetting and drawing method with a heating temperature of 1080℃-1100℃. The 3rd and 4th fires adopt double V drawing forming. The double V is divided into 3 passes of drawing. The deformation of the 1st and 2nd passes is 15-20%, the deformation of the 3rd pass is 3-7%, and the heating temperature is 1050℃-1080℃.

5. The method for preparing a Ni-Fe-based high-temperature alloy bar billet for an ultra-supercritical thermal power unit with a high yield rate according to claim 4, characterized in that: In the S3, the 2-3 fire forging reduction rate is 30mm / s-50mm / s, and the 4-5 fire forging adopts a circle-circle deformation method.

6. The method for preparing a Ni-Fe-based high-temperature alloy bar billet for an ultra-supercritical thermal power unit with a high yield rate according to claim 1, characterized in that: The rounding anvil in S4 is a spring anvil or a U-shaped anvil with a tolerance range of (+2, -1) mm. After rounding, the rod is air-cooled and the straightness of the rod blank meets the requirement of ≤2 mm / m.

7. The method for preparing a Ni-Fe-based high-temperature alloy bar billet for an ultra-supercritical thermal power unit with a high yield rate according to claim 1, characterized in that: The peeling diameter range of the forged bar in S5 is controlled within the range of (+1, -1) mm, and the resulting Ni-Fe-based high-temperature alloy bar blank can be directly used for supercritical thermal power unit parts, and the forging finished product rate is not less than 85%.

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