Heat treatment process method for improving low-temperature impact toughness of wind power gear ring

Abstract

The invention belongs to the technical field of heat treatment, and particularly relates to a heat treatment process method for improving low-temperature impact toughness of a wind power gear ring, the heat treatment process method comprises a quenching process and a tempering process, the quenching process comprises the following steps: (1) heating to 860 + / -10 DEG C, introducing nitrogen, and preserving heat until the structure is completely austenitized; (2) cooling and quenching are conducted, the quenching temperature is not higher than the austenitizing temperature, and low-concentration water-based quenching liquid is selected as quenching liquid; (3) cooling to 200 DEG C, discharging and air-cooling; the tempering process comprises the following steps: (a) tempering at a high temperature of 550-600 DEG C within 1-2 hours after quenching; and (b) air cooling is carried out after tempering is completed. On the basis of ensuring the hardness of the workpiece, the low-temperature impact toughness of the workpiece is improved, the deformation of the workpiece is improved, and the plasticity and toughness of the workpiece are improved.

Description

Technical Field

[0001] The present invention belongs to the field of heat treatment technology, and in particular relates to a heat treatment process method for improving the low-temperature impact toughness of a wind turbine gear ring. Background Art

[0002] At present, with the continuous innovation of design concepts and design requirements in the wind power field, various new types of boxes and units are constantly coming out, and the requirements for the use of key structural parts are also constantly increasing. On the basis of the original requirements, higher requirements for wear resistance and durability are put forward.

[0003] In view of the above characteristics, the heat treatment of new key structural parts cannot, like the existing technology, blindly pursue the matrix hardness of the workpiece and lower the requirements for toughness; nor can it endlessly increase the reserve in order to ensure the subsequent processing of the workpiece, which will greatly increase the time cost of subsequent processing. Summary of the Invention

[0004] The purpose of the present invention is to solve the defects and shortcomings in the prior art and to provide a heat treatment process method for improving the low-temperature impact toughness of a wind turbine gear ring. The method can improve the low-temperature impact toughness of the workpiece, improve the deformation of the workpiece, and increase the plastic toughness of the workpiece while ensuring the hardness of the workpiece.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a heat treatment process method for improving the low-temperature impact toughness of a wind turbine gear ring, including a quenching process and a tempering process, wherein:

[0006] The quenching process comprises the following steps:

[0007] (1) Heating to 860±10℃, keeping warm under nitrogen until the structure is completely austenitized;

[0008] (2) Cooling quenching, in which the quenching temperature is not higher than the austenitizing temperature, and the quenching liquid is a low-concentration water-based quenching liquid;

[0009] (3) Cool to 200℃ and then take out of the furnace for air cooling;

[0010] The tempering process comprises the following steps:

[0011] (a) Use high temperature tempering at 550-600℃ within 1-2 hours after quenching;

[0012] (b) After tempering, air cooling is performed.

[0013] Preferably, the quenching process step (1) adopts a two-stage stepped tempering process, with the temperature being averaged at 865°C for 60 minutes and at 860°C for 180 minutes.

[0014] Preferably, the nitrogen flow rate in the quenching process step (1) is 5m 3 / h.

[0015] Preferably, the quenching liquid in the quenching process step (2) is PAG quenching liquid.

[0016] Preferably, the high temperature tempering temperature in the tempering process step (a) is 550-580° C. and the time is 360 minutes.

[0017] Preferably, the normal temperature impact of the gear ring subjected to the heat treatment process is increased from 80Akv / J to 110Akv / J, and the low temperature impact is increased from 30-40Akv / J to 70-90Akv / J.

[0018] Preferably, the outer diameter expansion of the gear ring subjected to the heat treatment process is reduced from 10 mm to 8 mm.

[0019] After adopting the above technical solution, the heat treatment process method for improving the low-temperature impact toughness of a wind turbine gear ring provided by the present invention has the following beneficial effects:

[0020] 1) The quenching temperature of the present invention only needs to be no higher than the austenitizing temperature, that is, a higher quenching temperature can be selected. At the same time, the present invention uses a low-concentration water-based quenching liquid and cools to 200°C before being taken out of the furnace, which can achieve a faster cooling rate, thereby improving the low-temperature impact of the workpiece, reducing the deformation of large thin-walled gear rings, improving the plastic toughness of the workpiece, and increasing the service life of the workpiece;

[0021] 2) The present invention can facilitate the control of the overall tempering time by increasing the cooling furnace temperature, improve the tempering production efficiency and reduce deformation, reduce the difficulty of subsequent processing, improve production efficiency and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the quenching process curve diagram of the present invention;

[0023] Figure 2 It is the tempering process curve diagram of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described clearly and completely below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the embodiments described are only some, not all, of the embodiments of the present invention. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention, its application, or use. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0025] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0026] Unless otherwise specifically stated, the relative arrangement of the parts and steps, the numerical expressions and the numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0027] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0028] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0029] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0030] like Figure 1-2 As shown, this embodiment provides a heat treatment process method for improving the low-temperature impact toughness of a wind turbine gear ring. Taking a 42CrMo4 gear ring as an example, the heat treatment process parameters of other materials can be adjusted according to their phase change transformation points, including quenching process and tempering process, wherein,

[0031] The quenching process comprises the following steps:

[0032] (1) Heating to 860±10℃, and keeping warm with nitrogen until the structure is completely austenitized. Specifically, a two-stage step tempering process is adopted, with an average temperature of 60min at 865℃ and an average temperature of 180min at 860℃. The nitrogen flow rate is 5m 3 / h;

[0033] (2) Cooling quenching: In order to improve the hardness of the workpiece after quenching, the quenching temperature can be greatly increased. The quenching temperature should not be higher than the austenitizing temperature, and the quenching liquid should be a low-concentration water-based quenching liquid (PAG);

[0034] (3) Cool to 200℃ and then take out of the furnace for air cooling;

[0035] The tempering process comprises the following steps:

[0036] (a) After quenching, high temperature tempering is performed at 550-600°C within 1-2 hours, wherein the high temperature tempering temperature is preferably 550-580°C and the time is 360 minutes (the tempering time can be appropriately increased according to the wall thickness of the workpiece);

[0037] (b) After tempering, air cooling is performed.

[0038] As we all know, when using traditional quenching and tempering processes, the quenching temperature is generally selected to be low. At this time, in order to ensure hardness and control deformation of the workpiece, it is usually necessary to cool to around 100°C and adopt a relatively slow cooling rate, that is, to select a coolant with a higher concentration. Taking the above-mentioned ring gear as an example, on the basis of ensuring strength, room temperature impact can usually meet the workpiece requirements, which is about 80Akv / J. However, when the impact specimen is cooled to -40°C, the impact energy is only half of that at room temperature, and may even be lower than 30Akv / J due to the influence of the material.

[0039] After the above-mentioned heat treatment process method for improving the low-temperature impact toughness of the wind turbine gear ring is implemented, the hardness of the workpiece can still be maintained, but the room temperature impact is improved from the original 80Akv / J to 110Akv / J. At the same time, the low-temperature impact is also significantly improved, about 60% of the room temperature, from the original 30-40Akv / J to 70-90Akv / J.

[0040] Taking the above-mentioned ring gear as an example, when using the traditional process, the outer circle expansion is maintained at about 10mm, but after the above-mentioned process method is implemented, the outer circle expansion is also improved, and the outer circle expansion is reduced to about 8mm. For details, please refer to the comparison of the deformation parameters of the ring gear under the original process and the deformation parameters of the ring gear after the improved process in Table 1-2 below.

[0041]

[0042] Table 1 Deformation of gear ring under original process

[0043]

[0044] Table 2 Gear ring deformation after process improvement

[0045] In summary, the present invention provides a heat treatment process method for improving the low-temperature impact toughness of a wind turbine gear ring, which can improve the low-temperature impact toughness of the workpiece, improve the deformation of the workpiece, and increase the plastic toughness of the workpiece while ensuring the hardness of the workpiece.

[0046] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A heat treatment process for improving the low-temperature impact toughness of a wind turbine gear ring, characterized in that: Including quenching process and tempering process, among which, The quenching process comprises the following steps: (1) Heating to 860±10℃, keeping warm under nitrogen until the structure is completely austenitized; (2) Cooling quenching, in which the quenching temperature is not higher than the austenitizing temperature, and the quenching liquid is a low-concentration water-based quenching liquid; (3) Cool to 200℃ and then take out of the furnace for air cooling; The tempering process comprises the following steps: (a) Use high temperature tempering at 550-600℃ within 1-2 hours after quenching; (b) After tempering, air cooling is performed.

2. The heat treatment process for improving the low-temperature impact toughness of a wind turbine gear ring according to claim 1, characterized in that: The quenching process step (1) adopts a two-stage stepped tempering process, with a temperature equalization stage of 60 minutes at 865°C and a temperature equalization stage of 180 minutes at 860°C.

3. The heat treatment process for improving the low-temperature impact toughness of a wind turbine gear ring according to claim 1, characterized in that: The nitrogen flow rate in the quenching process step (1) is 5m 3 / h.

4. The heat treatment process for improving the low-temperature impact toughness of a wind turbine gear ring according to claim 1, characterized in that: In the quenching process step (2), the quenching liquid is selected from PAG quenching liquid.

5. The heat treatment process for improving the low-temperature impact toughness of a wind turbine gear ring according to claim 1, characterized in that: In the tempering process step (a), the high temperature tempering temperature is 550-580° C. and the time is 360 minutes.

6. The heat treatment process for improving the low-temperature impact toughness of a wind turbine ring gear according to claim 1, characterized in that: The normal temperature impact of the gear ring subjected to the heat treatment process is increased from 80Akv / J to 110Akv / J, and the low temperature impact is increased from 30-40Akv / J to 70-90Akv / J.

7. The heat treatment process for improving the low-temperature impact toughness of a wind turbine gear ring according to claim 1, characterized in that: The outer diameter expansion of the gear ring subjected to the heat treatment process is reduced from 10 mm to 8 mm.

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