阅读说明：本技术 风力发电机组齿轮箱滚道行星轮渗碳淬火工艺 (Carburizing and quenching process for planet wheel of gear box roller path of wind generating set ) 是由 陈葵 邱荣春 胡林森 胡云波 黄俊琼 朱美玲 于 2021-07-22 设计创作，主要内容包括：本发明公开了一种风力发电机组齿轮箱滚道行星轮渗碳淬火工艺,包括如下步骤：对工件进行高碳势渗碳；其中渗碳温度为940±10℃,强渗碳势为1.2～1.3％,扩散碳势为0.9～1.1％；对经过第一步中高碳势渗碳处理的工件进行先固溶处理然后高温时效或先缓冷处理后球化退火。该工艺能够使淬火和低温回火后的工件渗碳层表面金相组织为回火马氏体+残余奥氏体+弥散细小的合金碳化物,工件的表面碳浓度为0.85％以上,渗层表面硬度能够达到HRC60.0以上,其中渗层表面59.0HRC的淬硬层可达到整个渗层有效硬化层深的50％以上,因此在行星轮齿部和内孔表面磨削后,仍然能够具有较高的接触疲劳强度和良好的综合机械性能。(The invention discloses a carburizing and quenching process for a roller path planet wheel of a gear box of a wind generating set, which comprises the following steps of: performing high carbon potential carburization on the workpiece; wherein the carburizing temperature is 940 +/-10 ℃, the strong carburizing potential is 1.2-1.3%, and the diffusion carbon potential is 0.9-1.1%; and (3) carrying out solid solution treatment and then high-temperature aging treatment or firstly carrying out slow cooling treatment and then carrying out spheroidizing annealing on the workpiece subjected to the high-carbon potential carburizing treatment in the first step. The process can lead the metallographic structure of the surface of the carburized layer of the workpiece after quenching and low-temperature tempering to be tempered martensite, residual austenite and dispersed fine alloy carbide, the surface carbon concentration of the workpiece is more than 0.85 percent, the surface hardness of the carburized layer can reach more than HRC60.0, and the hardening layer of 59.0HRC of the carburized layer surface can reach more than 50 percent of the effective hardening layer depth of the whole carburized layer, so that the carburized layer can still have higher contact fatigue strength and good comprehensive mechanical property after the tooth part and the inner hole surface of the planet wheel are ground.)

1. A carburizing and quenching process for a planet wheel of a gear box raceway of a wind generating set is characterized by comprising the following steps of:

firstly, carburizing a workpiece with high carbon potential;

wherein the carburizing temperature is 940 +/-10 ℃, the strong carburizing potential is 1.2-1.3%, and the diffusion carbon potential is 0.9-1.1%;

secondly, carrying out solution treatment and then high-temperature aging treatment on the workpiece subjected to the high-carbon potential carburization treatment in the first step or

Firstly, annealing by slow cooling and then spheroidizing.

2. The carburizing and quenching process for the planet wheels of the roller path of the gearbox of the wind generating set according to claim 1, wherein the specific steps of solution treatment and high-temperature aging are as follows:

s1, cooling the furnace to 900 +/-10 ℃ after the carburization in the first step is finished, and then discharging the steel for oil cooling;

s2, aging at the high temperature of 650 +/-10 ℃;

s3, quenching and low-temperature tempering.

3. The carburizing and quenching process for the planet wheels of the gear way of the wind generating set according to claim 2, wherein the metallographic structure of the workpiece carburized layer after oil cooling in the step S1 comprises super-cooled austenite, quenched martensite and fine alloy carbide, wherein the area percentage of the super-cooled austenite is more than 50%.

4. The carburizing and quenching process for the planet wheels of the roller path of the gearbox of the wind generating set according to claim 3, wherein the process is suitable for workpieces with the wall thickness from the root circle to the inner hole being more than or equal to 70mm, the gear module being more than or equal to 16mm, the single side of the grinding allowance in the tooth thickness direction after carburizing and quenching being less than or equal to 0.4mm, and the single side of the grinding allowance of the inner hole being less than or equal to 0.8 mm.

5. The carburizing and quenching process for the planet wheels of the gear way of the wind generating set according to claim 1, which is characterized in that the specific steps of firstly slow cooling treatment and then spheroidizing annealing are as follows:

SS1, cooling to 850 +/-10 ℃ in a furnace after the carburization in the first step is finished, and then discharging to a slow cooling chamber to be cooled to below 300 ℃;

SS2, isothermal spheroidizing annealing or periodic spheroidizing annealing;

SS3, quenching and low-temperature tempering.

6. The carburizing and quenching process for the planet wheels of the gearbox roller path of the wind generating set according to claim 5, wherein a nitrogen atmosphere is adopted in the slow cooling chamber, a circulating fan is arranged in the slow cooling chamber, and a cooling circulating water cooling jacket is arranged on the wall of the slow cooling chamber.

7. The carburizing and quenching process for the planet wheels of the gearbox roller path of the wind generating set according to claim 5, wherein the high-temperature heating and heat-preserving temperatures of isothermal spheroidizing annealing or periodic spheroidizing annealing are both Ac₁+ 20-30 ℃ and spheroidizing isothermal temperature of Ar₁-20～30℃。

8. The carburizing and quenching process for the planet wheels of the gearbox roller path of the wind generating set according to claim 5, wherein the high-temperature heating and heat-preserving temperature of isothermal spheroidizing annealing or periodic spheroidizing annealing is 760 +/-10 ℃, and the spheroidizing isothermal temperature is 650 +/-10 ℃.

9. The carburizing and quenching process for the planet wheels of the gearbox roller path of the wind generating set according to claim 7, wherein the periodic spheroidizing annealing process is not less than two periods.

10. The carburizing and quenching process for the planet wheels of the roller path of the gearbox of the wind generating set according to claim 7, wherein the process is suitable for workpieces with the wall thickness from the root circle to the inner hole being less than 70mm, the gear module being less than 16mm, the single side of the grinding allowance in the tooth thickness direction after carburizing and quenching being more than 0.4mm, and the single side of the grinding allowance of the inner hole being more than 0.8 mm.

Technical Field

The invention belongs to the technical field of metal material heat treatment, and particularly relates to a carburizing and quenching process for a roller path planet wheel of a gear box of a wind generating set.

Background

The gear box of the wind generating set is used as a key component of the wind generating set, the maintenance and replacement cost is high, and the service life of the wind generating set is directly influenced. As the megawatt number of the wind generating set is larger and larger, the weight and the volume of the gear box limit the megawatt number of the wind generating set to be increased, and the lightweight design of the gear box becomes a trend, the planet wheel of the wind generating set adopts a roller path planet wheel, and the surface design of an inner hole as a bearing roller path is the mainstream design of the gear box of the large megawatt wind generating set at present. The raceway planet wheel of the wind generating set gear box needs higher contact fatigue strength and good comprehensive mechanical property except for tooth meshing transmission, and the surface of an inner hole is used as a bearing raceway to bear high load and high speed operation of a bearing roller, so that the requirement on the contact fatigue strength is higher.

Because of the deformation of carburizing and quenching of the inner hole of the raceway planet wheel, the removal of the machining allowance of the surface of the inner hole reaches about 0.7-1.0 mm of a single side, the prior art is difficult to ensure the high hardness and the larger contact fatigue strength of the surface of the inner hole of the raceway planet wheel under the condition of removing the large allowance, and when the condition is improved by adopting a high-carbon-concentration carburizing and quenching process method, large net-shaped, horn-shaped and block-shaped carbides are easily formed, and as a result, as shown in figure 1 of the attached drawing of the specification, the carbides are easy to form stress concentration and weaken crystal boundary, so that the surface of a carburized layer of a workpiece is large in brittleness and fails early, and the invention provides the following technical scheme in order to solve the problems.

Disclosure of Invention

The invention aims to provide a carburizing and quenching process for a roller path planet wheel of a gear box of a wind generating set, which solves the following technical problems:

(1) how to ensure the high hardness and the larger contact fatigue strength of the inner hole surface of the raceway planet wheel under the condition of removing large allowance;

(2) how to avoid forming large net-shaped, horn-shaped and blocky carbides in the high-carbon-concentration carburizing and quenching process method, reduce the surface brittleness of the carburized layer of the workpiece, and prolong the effective service life of the workpiece.

The purpose of the invention can be realized by the following technical scheme:

a carburizing and quenching process for a planet wheel of a gear box raceway of a wind generating set comprises the following steps:

firstly, carburizing a workpiece with high carbon potential;

wherein the carburizing temperature is 940 +/-10 ℃, the strong carburizing potential is 1.2-1.3%, and the diffusion carbon potential is 0.9-1.1%;

secondly, carrying out solution treatment and then high-temperature aging treatment on the workpiece subjected to the high-carbon potential carburization treatment in the first step or

Firstly, annealing by slow cooling and then spheroidizing.

As a further proposal of the invention, the concrete steps of solution treatment and high-temperature aging are firstly

S1, cooling the furnace to 900 +/-10 ℃ after the carburization in the first step is finished, and then discharging the steel for oil cooling;

s2, aging at the high temperature of 650 +/-10 ℃;

s3, quenching and low-temperature tempering.

As a further scheme of the invention, the metallographic structure of the workpiece infiltrated layer after the oil cooling in the step S1 comprises super-cooled austenite, quenched martensite and fine alloy carbide, and is characterized in that the area percentage of the super-cooled austenite reaches more than 50%.

As a further scheme of the invention, the process is suitable for workpieces with the wall thickness from the root circle to the inner hole being more than or equal to 70mm, the gear module being more than or equal to 16mm, the single side of the grinding allowance in the tooth thickness direction after carburizing and quenching being less than or equal to 0.4mm, and the single side of the grinding allowance of the inner hole being less than or equal to 0.8 mm.

As a further scheme of the invention, the specific steps of the spheroidizing annealing after the slow cooling treatment are as follows:

SS1, cooling to 850 +/-10 ℃ in a furnace after the carburization in the first step is finished, and then discharging to a slow cooling chamber to be cooled to below 300 ℃;

SS2, isothermal spheroidizing annealing or periodic spheroidizing annealing;

SS3, quenching and low-temperature tempering.

As a further scheme of the invention, the slow cooling chamber is filled with nitrogen, the slow cooling chamber is internally provided with a circulating fan, and the wall of the slow cooling chamber is provided with a cooling circulating water cooling jacket.

As a further proposal of the invention, the high-temperature heating and heat-preserving temperature of isothermal spheroidizing annealing or periodic spheroidizing annealing is Ac₁+ 20-30 ℃ and spheroidizing isothermal temperature of Ar₁-20～30℃。

As a further scheme of the invention, the high-temperature heating and heat-preserving temperature of isothermal spheroidizing annealing or periodic spheroidizing annealing is 760 +/-10 ℃, and the spheroidizing isothermal temperature is 650 +/-10 ℃.

As a further scheme of the invention, the periodic spheroidizing annealing process is not less than two periods.

As a further scheme of the invention, the process is suitable for workpieces with the wall thickness from the root circle to the inner hole being less than 70mm, the gear module being less than 16mm, the single side of the grinding allowance in the tooth thickness direction after carburizing and quenching being more than 0.4mm, and the single side of the grinding allowance of the inner hole being more than 0.8 mm.

The invention has the beneficial effects that:

the process of the invention firstly carries out high carbon potential carburization on a workpiece, and after carburization, a treatment mode of firstly carrying out solid solution treatment and then carrying out high temperature aging or firstly carrying out slow cooling and then carrying out spheroidizing annealing is adopted, so that the metallographic structure of the surface of a carburized layer of the workpiece after quenching and low temperature tempering is tempered martensite, residual austenite and finely dispersed alloy carbide, the surface carbon concentration of the workpiece is more than 0.85 percent, the surface hardness of the carburized layer can reach more than HRC60.0, wherein the hardening layer of the carburized layer surface 59.0HRC can reach more than 50 percent of the depth of an effective hardening layer of the whole carburized layer, and therefore, after the tooth part and the inner hole surface of the planet wheel are ground, the carburized layer still has higher contact fatigue strength and good comprehensive mechanical property.

Drawings

The invention will be further described with reference to the accompanying drawings.

FIG. 1 is an enlarged view of large reticulated, angular, bulk carbides formed in a high carbon concentration carburizing and quenching process;

FIG. 2 is a schematic illustration of a carburizing and quenching process using solution treatment + high temperature aging;

FIG. 3 is a gold phase diagram of a workpiece treated with solution treatment followed by high temperature aging treatment, wherein white dots are finely dispersed alloy carbides;

FIG. 4 is a schematic diagram of a carburizing and quenching process using isothermal spheroidizing annealing;

FIG. 5 is a schematic illustration of a carburizing and quenching process employing periodic spheroidizing annealing;

FIG. 6 is a metallographic picture of a workpiece prepared by a carburizing and quenching process employing periodic spheroidizing annealing, wherein white dots are finely dispersed alloy carbides.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A carburizing and quenching process for a planet wheel of a gear box raceway of a wind generating set comprises the following steps:

firstly, carburizing a workpiece with high carbon potential;

wherein the carburizing temperature is 940 +/-10 ℃, the strong carburizing potential is 1.2-1.3%, the diffusion carburizing potential is 0.9-1.1%, and the carburizing time is determined according to the technical requirement of the effective hardening layer depth of the workpiece, so that free carbide is generated after the workpiece carburized layer is quenched;

secondly, adopting a treatment mode of firstly carrying out solution treatment and then carrying out high-temperature aging on the workpiece subjected to the high-carbon-potential carburization treatment in the first step or

A treatment mode of firstly carrying out slow cooling treatment and then carrying out spheroidizing annealing;

as shown in fig. 2, the treatment method of solution treatment and then high-temperature aging is specifically as follows:

s1, cooling the furnace to 900 +/-10 ℃ after the carburization in the first step is finished, and then discharging the furnace and cooling the oil to below 100 ℃;

in one embodiment of the invention, in order to reduce thermal deformation, a nitrate salt bath is adopted for cooling, and the cooling temperature is properly increased to about 200 ℃;

after oil cooling, the metallographic structure of the workpiece infiltrated layer is super-cooled austenite, quenched martensite and a small amount of fine alloy carbide;

wherein the content of the super-cooled austenite reaches more than 50 percent, and most alloy carbides are dissolved in the super-cooled austenite in a solid solution manner;

s2, adopting high temperature aging at 650 +/-10 ℃, and calculating the heat preservation time according to the effective section of the workpiece;

specifically, the holding time is about: (2h-4h)/100 mm;

in the step, fine, dispersed and uniform alloy carbide is precipitated from the infiltrated layer undercooled austenite, fine, dispersed and uniform third-time alloy carbide is also precipitated from the infiltrated layer quenched martensite,

s3, quenching, low-temperature tempering and air cooling to obtain a finished product;

wherein the quenching is isothermal quenching at the temperature of 820-830 ℃;

cooling the quenched workpiece to below 100 ℃ in oil;

the low-temperature tempering is heat preservation treatment at the temperature of 170-180 ℃ for preset time;

the metallographic structure on the surface of the carburized layer of the workpiece treated in the step forms tempered martensite, residual austenite and dispersed fine alloy carbide, and the structure has high contact fatigue strength and good comprehensive mechanical property.

As shown in figure 3, the workpiece structure adopting the process is tempered hidden needle martensite, retained austenite and dispersed fine alloy carbide, the surface carbon concentration is 0.98%, the surface hardness is 62.1HRC, the effective layer depth is 3.20mm, the hardness value at the position of the layer depth of 1.60mm is 697HV (converted into 59.4HRC), and the hardening layer meeting the requirement of 59.0HRC of the surface of the infiltration layer can reach more than 50% of the effective hardening layer depth of the whole infiltration layer;

the process is suitable for heat treatment of workpieces with large effective sections and small heat treatment distortion;

specifically, in one embodiment, the method is used for processing a workpiece with a root circle, a wall thickness of an inner hole being more than or equal to 70mm, a gear module being more than or equal to 16mm, a single side of a grinding allowance in the tooth thickness direction after carburizing and quenching being less than or equal to 0.4mm, and a single side of a grinding allowance of the inner hole being less than or equal to 0.8 mm;

as shown in fig. 4 and 5, the specific treatment method of the annealing by slow cooling and then spheroidizing is as follows:

SS1, cooling to 850 +/-10 ℃ after carburizing, discharging to a slow cooling chamber and cooling to below 300 ℃;

in the process, the metallographic structure of the workpiece infiltrated layer is converted from austenite into pearlite, a large amount of reticular and horn alloy carbide and a small amount of bainite and martensite structures;

the slow cooling chamber is protected by nitrogen to prevent decarburization and oxidation, the circulating fan ensures uniform cooling, and the cooling speed can be accelerated by the cooling of the chamber wall provided with a cooling circulating water cooling jacket.

The slow cooling speed of the workpiece can be adjusted in a small range by finely adjusting the air volume of the circulating fan, the water volume of cooling circulating water and the nitrogen flow, the cooling speed can be adjusted to be slightly larger or smaller than air cooling, and the size, the shape and the quantity of the alloy carbide precipitated in the slow cooling process are properly controlled;

SS2, isothermal spheroidizing annealing or periodic spheroidizing annealing;

in the step, the reticular and angular alloy carbide is converted into fine, dispersed and uniform alloy carbide;

the high-temperature heating and heat preservation temperature of isothermal spheroidizing annealing or periodic spheroidizing annealing is 760 +/-10 ℃ (about Ac)₁+ 20-30 ℃), and the spheroidization isothermal temperature is recommended to be 650 +/-10 ℃ (about Ar)₁-20-30 ℃), and the specific heat preservation time is calculated and set according to the effective section of the workpiece;

the high-temperature heating and heat preservation of the workpiece is the temperature of a two-phase region, the structure is recombined into austenite and fine dispersion alloy carbide, wherein the fine alloy carbide can be used as a carbide nucleation particle of subsequent spheroidizing annealing, and the structure is converted into pearlite and fine dispersion alloy carbide in the spheroidizing isothermal process;

in the application, an isothermal spheroidizing annealing process or a periodic spheroidizing annealing process is specifically selected and determined according to the size, the quantity and the shape of carbides in the early carburizing process, the periodic spheroidizing annealing process is not less than two periods, and the spheroidizing effect is better.

SS3, quenching, low-temperature tempering, and then air-cooling to obtain a finished product;

wherein the quenching is that the workpiece is insulated for a preset time at the temperature of 820-;

cooling the quenched workpiece out of the furnace to below 100 ℃;

the low-temperature tempering is that the temperature is kept at 170-180 ℃ for a preset time;

the metallographic structure on the surface of the carburized layer of the workpiece treated by the step forms tempered martensite, residual austenite and dispersed fine alloy carbide.

As shown in fig. 6, the metallographic structure of the workpiece obtained by the carburizing and quenching process with periodic spheroidizing annealing is tempered cryptopin martensite, retained austenite and finely dispersed alloy carbide, the surface carbon concentration is 1.02%, the surface hardness is 62.5HRC, the effective depth of layer is 4.3mm, the hardness value at the depth of layer of 2.15mm is 695HV (converted into 59.3HRC), and the depth of the hardened layer at 59.0HRC on the surface of the carburized layer can reach more than 50% of the effective hardened layer depth of the whole carburized layer.

The process is suitable for heat treatment of workpieces with small effective sections and large heat treatment distortion;

specifically, the method is used for processing a workpiece with a tooth root circle to an inner hole wall thickness of less than 70mm, a gear module of less than 16mm, a single side of grinding allowance in the tooth thickness direction of more than 0.4mm after carburizing and quenching, and a single side of grinding allowance of the inner hole of more than 0.8mm in one embodiment;

in one embodiment of the invention, the workpiece material for which the above-described treatment process is directed is 18CrNiMo7-6 carburized gear steel.

The embodiments of the present invention have been described in detail, but the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.