阅读说明：本技术 一种在同一零件上不同部位进行差深渗碳的方法 (Method for performing differential deep carburization on different parts of same part ) 是由 邱荣春 陈葵 黄俊琼 文毅 章永康 朱美玲 于 2020-07-15 设计创作，主要内容包括：本发明提供一种在同一零件上不同部位进行差深渗碳的方法,其采用脉冲式叠加渗碳的工艺方法先对要求深渗碳层深的部位进行渗碳,其余部位防渗保护,冷却除防渗保护后再同时对整个零件进行二次叠加渗碳,从而达到同一零件的不同部位有不同的渗碳层深度,在对要求深层深渗碳的部位进行二次叠加渗碳时的渗碳层深不可控过程中,在Ac3以上温度阶段采取斜率升、降温的方式进行过程控制,确保渗碳层深精准可控,根据渗碳深度的近似计算F.E.Harris公式的简化公式：<Image he="74" wi="265" file="DDA0002585062610000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>可设差深渗碳的经验公式：<Image he="98" wi="700" file="DDA0002585062610000012.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>通过工艺试验及验证得出k′<Sub>1</Sub>、k′<Sub>2</Sub>值,从而达到精准的控制同一零件的不同部位有不同的渗碳层深度。(The invention provides a method for carrying out differential deep carburization on different parts of the same part, which adopts a pulse type superimposed carburization process method to firstly carburize the part requiring deep carburization layer depth, and simultaneously carries out secondary superimposed carburization on the whole part after the other parts are subjected to anti-seepage protection and are cooled except the anti-seepage protection, thereby achieving that different parts of the same part have different carburization layer depths, and in the uncontrollable carburization layer depth process when the part requiring deep carburization is subjected to secondary superimposed carburization, the process control is carried out by adopting a slope increasing and reducing mode at the temperature stage above Ac3 to ensure that the carburization layer depth is accurately controllable, and the simplified formula of the F.E.Harris formula is calculated according to the approximation of the carburization depth: an empirical formula for differential carburization can be set: k 'is obtained through process test and verification' 1 、k′ 2 The method can accurately control different carburized layer depths of different parts of the same part.)

1. A method for performing differential deep carburization on different parts of the same part is characterized by comprising the following steps:

(1) determining the depth of carburized layers to be carburized at different parts on the part according to design requirements;

(2) a simplified formula of the f.e.harris formula is calculated from an approximation of the carburized depth:

h-carburization depth (mm);

k is the carburization rate factor;

t-carburizing time (h).

The pulse type superimposed carburizing empirical formula for setting differential deep carburizing is as follows:

in the formula H₁-depth of first pre-carburization (mm);

H₂II times shallow deep carburization depth (mm);

H_Δ-deep layer depth (mm) of pack cementation;

k₁-first carburization rate factor;

k₂-second carburization rate factor;

k′₁-a carburization rate factor for the superimposed carburization process;

k′₂-the carburization speed factor during the ramp up and down process;

t₁time to carburize I (hard carburization + diffusion) (h);

t₂time to carburize II (hard carburization + diffusion) (h);

t_sII carburizing slope temperature rise time (h);

t_ji carburizing slope cooling time (h);

(3) the carburization speed factor k is obtained by carrying out process test calculation through the formula₁、k₂、k′₁、k′₂Calculating the carburization time of the first time of pre-carburization and the carburization time of the second time of shallow depth according to the designed carburized layer depth, and performing differential deep carburization on the part by adopting a pulse type superimposed carburization process；

(4) Firstly, carburizing the part requiring deep carburized layer depth for the first time, and performing anti-seepage protection on the other parts;

(5) cooling to remove the anti-seepage protection, and simultaneously performing secondary superimposed carburizing on the whole part, so that the part requiring deep carburized layer depth is subjected to two times of carburizing to obtain deeper carburized layer depth, and the other parts obtain shallower carburized layer depth;

(6) in the uncontrollable process when the part requiring deep layer deep carburization is subjected to secondary superimposed carburization, the process is controlled in a slope rising and cooling mode at the temperature stage above Ac3, so that the depth of the carburized layer is ensured to be controllable.

2. The method of claim 1, wherein when the material of the component is 16Cr3NiWMoVNbE, the design requirements are that the carburizing temperature is 920 ℃, the carburizing potential is 1.10C, the diffusion carbon potential is 0.9C, the diffusion ratio is 2: 1;

the pulse type secondary superposition carburization empirical formula of the differential deep carburization is as follows:

Technical Field

The invention relates to the technical field of metal heat treatment, in particular to a method for performing differential deep carburization on different parts of the same part.

Background

With the rapid development of the mechanical industry in China, the requirement on the reliability of the whole equipment is higher and higher, so that higher requirements on the reliability and the structural compactness of parts of the equipment are further provided. In the prior gear box, an inner hole of a planet gear is generally linked with an outer ring of a bearing, an interference fit linking mode is adopted, the inner hole wall of the planet gear is thin, the tooth root stress is high, the inner hole is matched with the outer ring of the bearing and is easy to slip and creep to generate abrasion, the total weight is heavy, and the reliability is not high. At present, a planet wheel of a certain gear box is designed into a gear and bearing integrated structure, and an inner hole of the planet wheel is a raceway of an outer ring of a bearing, so that the whole transmission system is more compact in structure and higher in reliability. This integral type planet wheel structure still needs to satisfy the requirement that the planet wheel hole is as the bearing inner race when satisfying the gear requirement, and planet wheel flank of tooth and hole all need carry out the carburizing and quenching, and will have different carburization layer degree of depth, for satisfying the carburization layer depth that different positions required inconsistency on same part, need study a process method of poor deep carburization.

Disclosure of Invention

The invention aims to provide a method for performing differential deep carburization on different parts of the same part, and aims to solve the problem that the technical requirements of different parts of a low-carbon alloy carburized steel part in the prior art are inconsistent in carburized layer depth.

The technical scheme of the invention is as follows:

a method for performing differential deep carburization on different parts of the same part comprises the following steps:

(1) determining the depth of carburized layers to be carburized at different parts on the part according to design requirements;

(2) a simplified formula of the f.e.harris formula is calculated from an approximation of the carburized depth:

wherein H-carburization depth (mm);

k-carburization rate factor;

t-carburizing time (h).

The pulse type superimposed carburizing empirical formula for setting differential deep carburizing is as follows:

in the formula H₁-I pre-carburization depths (mm);

H₂-second superficial deep carburization depth (mm);

H_Δ-deep layer depth (mm) of super carburization;

k₁-I carburization rate factor;

k₂-second carburization rate factor;

k′₁-a superimposed carburization process carburization rate factor;

k′₂-a slope ramping process carburization speed factor;

t₁time for I carburization (hard carburization + diffusion) (h);

t₂time for II carburization (hard carburization + diffusion) (h);

t_sII carburizing slope temperature rise time (h);

t_ji carburizing slope cooling time (h);

(3) by passingThe carburization speed factor k is obtained by carrying out process test calculation through the formula₁、k₂、k′₁、K′₂Calculating the carburizing time I of pre-carburization and the carburizing time II of shallow depth according to the designed carburized layer depth, and performing differential deep carburization on the part by adopting a pulse type superimposed carburization process;

(4) firstly, carburizing the part requiring deep carburized layer depth for the first time, and performing anti-seepage protection on the other parts;

(5) cooling to remove the anti-seepage protection, and simultaneously performing secondary superimposed carburizing on the whole part, so that the part requiring deep carburized layer depth is subjected to two times of carburizing to obtain deeper carburized layer depth, and the other parts obtain shallower carburized layer depth;

(6) in the uncontrollable process when the part requiring deep layer deep carburization is subjected to secondary superimposed carburization, the process is controlled in a slope rising and cooling mode at the temperature stage above Ac3, so that the depth of the carburized layer is ensured to be controllable.

The method for performing differential deep carburization on different parts of the same part is characterized in that when the material of the part is 16Cr3NiWMoVNbE, the design requirements are that the carburization temperature is 920 ℃, the strong carburization potential is 1.10C%, the diffusion carbon potential is 0.9C%, the strong diffusion ratio is 2: 1;

the pulse type secondary superposition carburization empirical formula of the differential deep carburization is as follows:

the invention has the advantages that the pulse type superimposed carburization process method is adopted to firstly perform I times of carburization on the part requiring deep carburization layer depth, perform anti-seepage protection on the other parts, cool the parts except the anti-seepage protection, and simultaneously perform II times of superimposed carburization on the whole part, so that the part requiring deep carburization layer is subjected to secondary superimposed carburizationThe deep position obtains darker carburized layer after two carburizations, and other positions then obtain shallower carburized layer deeply, and thus reach the different positions of same part and have different carburized layer degree of depth, in the uncontrollable process of carburized layer depth when carrying out secondary stack carburization to the position that requires deep carburization, the mode that the slope rises, the cooling is taken to carry out process control at Ac3 above temperature stage, it is accurate controllable to ensure the carburized layer degree of depth, according to the simplified formula of the approximate calculation F.E.Harris formula of carburization degree of depth:

an empirical formula for differential carburization can be set:

k 'is obtained through process test and verification'₁、k′₂The method can accurately control different carburized layer depths of different parts of the same part, and is mainly suitable for low-carbon alloy carburized steel and suitable for parts with different carburized layer depths of different parts.

Drawings

FIG. 1 is a schematic diagram of a superimposed carburization test process.

Fig. 2 is a schematic diagram of a unified quenching process after carburization.

Fig. 3 is a schematic diagram of a pulse type superimposed carburization verification process of differential deep carburization.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

The embodiment of the method for performing differential deep carburization on different parts of the same part comprises the following steps:

(1) firstly, carrying out a carburizing process test according to the figure 1, wherein the specific process parameters are determined according to materials and actual conditions; in order to simplify the test process and reduce the variation of all factors, the fixed carburizing temperature, carbon potential and strong expansion ratio are selected during the test;

(2) during a carburization test, 6 samples requiring deep layer depth are placed for carburization for the first time, after the carburization for the first time is finished, the samples are slowly cooled, taken out of a furnace and cooled, 3 of the samples after the carburization for the first time are taken out, and then 3 samples requiring shallow layer depth are loaded for carburization for the second time;

(3) during the test, t is taken_s＝t_j＝2h、t_s＝t_jCarrying out two process tests for 4 h;

(4) uniformly performing high-temperature tempering at 680 ℃ for 5h (the high-temperature tempering process can be omitted according to materials), and performing quenching and tempering process tests according to the figure 2;

(5) the results of the tests carried out on the material 16Cr3NiWMoVNbE according to the above description with reference to FIGS. 1 and 2 are given in the following table:

table 116 Cr3NiWMoVNbE Steel Process test results

(6) According to a designed empirical formula:

the carburization time for the first time is 18 hours, when t_s＝t_j2H, layer depth H₁1.917mm, from a simplified formula: k is a radical of₁0.452; when t is_s＝t_j4H, layer depth H₁1.930mm, from a simplified formula: k is a radical of₁＝0.455。

The empirical formula for the first carburization is: when t is_s＝t_jWhen the reaction time is equal to 2h,when in use_s＝t_jWhen the reaction time is 4h, the reaction time is up to 4h,

the second carburization time is 9h, and the layer depth is not influenced by t_s、t_jTaking the mean of the depth of layer twice, then

H₂＝(1.356+1.362)÷2＝1.359_mmFrom the simplified equation: k is a radical of₂＝0.453。

The empirical formula for the second carburization is:

the depth of the I + II carburized layer can be obtained according to a design formula as follows:

solving equations (1), (2) can obtain:

k′₁＝0459，K′₂＝0.105

the empirical formula of the I + II times of superimposed carburization of the material under the conditions of the carburizing temperature, the carbon potential and the strong expansion ratio can be obtained as follows:

(7) according to the technical requirements of actual carburized layer depths of different parts of the part, substituting the technical requirements into an empirical formula of the material under the carburization condition to obtain the carburization time of the first time of pre-carburization and the carburization time of the second time of shallow layer depth.

(8) For example, in order to verify whether the empirical formula is accurate, process verification is carried out on a product with the inner hole carburized layer depth of 2.00-2.40 mm and the tooth part carburized layer depth of 1.05-1.35 mm according to the technical requirements; firstly, carburizing the inner hole of the product for one time to reach the expected carburized layer depth H before gear milling₁The other parts are plated with copper for anti-seepage protection, the inner hole is subjected to expected carburization and slow cooling for the first time, then the outer circle is milled, and then the inner hole and the tooth part are simultaneously subjected to carburization for the second time, so that the tooth part reaches the shallow carburized layer depth H required by the technology₂The deep carburized layer depth H of the inner hole reaches the technical requirement after I times and II times of superimposed carburization_Δ. Let t_s＝t_j2H, the depth of the inner bore carburized layer takes the intermediate value H of the technical requirement_Δ2.2mm, the depth of carburized layer of tooth part is also the intermediate value H of technical requirement₂1.2mm, from empirical formula:

the equation can be found:

solving equations (3), (4), (5) yields:

H₁＝1.551mm，t₁＝11.780h≈118h，t₂＝7.017h≈7h

thus, the pulse type superimposed carburization process curve of the differential deep carburization can be obtained as shown in the attached figure 3.

(9) After carburization according to fig. 3, high-temperature tempering is performed at 680 ℃ for 5 hours, and the quenching process is performed according to fig. 2. The physical and chemical detection results of the inner hole pre-permeation sample and the product physical anatomy of the process are verified by detection and shown in table 2, and all indexes meet the technical requirements:

TABLE 216 verification of Cr3NiWMoVNbE thermal treatment Process

Therefore, when the process method is applied to the problem that the technical requirements of carburized layer depths of different parts of the low-carbon alloy carburized steel part are not consistent, firstly, performing carburization I times on a part requiring deep carburization layer depth by adopting a pulse type superimposed carburization process method, the other parts are subjected to anti-seepage protection, the whole part is simultaneously subjected to secondary superimposed carburization after cooling and removing the anti-seepage protection, so that the part requiring deep carburized layer depth is subjected to two times of carburization to obtain a deeper carburized layer depth, while other parts can obtain a shallower carburized layer depth, so that different parts of the same part have different carburized layer depths, in the process of uncontrollable depth of carburized layer when the secondary superimposed carburization is carried out on the part requiring deep carburization, the process control is carried out in a slope rising and cooling mode at the temperature stage above Ac3, the depth of a carburized layer is ensured to be accurately controllable, and a simplified formula of an F.E.Harris formula is calculated according to the approximation of the carburized depth:an empirical formula for differential carburization can be set:

k 'is obtained through process test and verification'₁、k′₂The method can accurately control different carburized layer depths of different parts of the same part.

The material is mainly low-carbon alloy carburizing steel, and the product is mainly a part which needs different carburized layer depths for different parts.

In the description herein, references to the description of the terms "one embodiment," "certain embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

In summary, although the present invention has been described with reference to the preferred embodiments, the above-described preferred embodiments are not intended to limit the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, therefore, the scope of the present invention shall be determined by the appended claims.