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Novel nitriding process

A process, a new technology, applied in the direction of metal material coating process, coating, solid-state diffusion coating, etc., can solve the problems of low strength and service life, difficulty in stabilizing and controlling the quality of parts, and difficulty in increasing the depth of effective hardened layer, etc. Achieve the effect of satisfying the mechanical strength index, small deformation of the product, and good microstructure of the seepage layer

Inactive Publication Date: 2017-02-01
CHONGQING TIEMA IND GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, the nitriding process in the industry is mainly processed by the Bo-type furnace. Even if the commonly used infiltrating agents ammonium chloride, carbon tetrachloride, titanium tetrachloride and rare earth compounds are used, heat treatment is required for about 25 hours in order to achieve a layer depth of 0.3mm. It takes about 40 hours for 0.4mm, and 0.4mm is close to the processing limit of most enterprises at present; some foreign enterprises also use advanced equipment for vacuum gas soft nitriding and ion nitriding technology, and the layer depth can be further increased to 0.5mm, but the effective hardening layer depth It is difficult to improve; the two processes of vacuum gas nitrocarburization and ion nitriding require advanced equipment as support, and the capital investment is large
Therefore, the application of ion nitriding in China is limited, the process stability is poor, and the quality of parts is difficult to control stably
[0004] At present, the surface hardness of parts after nitriding treatment in the industry is difficult to break through 800HV, and the effective hardened layer depth (with 500HV as the lower limit) is less than 0.2mm. The speed meets the requirements of layer depth. Generally, 560-580°C is used for processing. The deformation of the parts is large at high temperature, and the hardness of the matrix will be reduced. After heat treatment, the deformation of the parts is large, and the strength is difficult to meet the requirements of heavy-duty vehicles; A new nitriding process with small deformation of parts after nitriding treatment, dimensional accuracy and mechanical strength indicators meeting product design requirements

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] The process of nitriding the output shaft of the ring gear includes the following steps: put the parts cleaned with a quick-drying cleaning agent into a nitriding furnace, pre-oxidize at 350°C for 1 hour, and then pass ammonia gas and a permeation agent, And exhaust, heat up to 540°C, the heating time is 15min, then continue to feed ammonia gas and permeation agent, keep warm and nitriding at 540°C for 16h, and then air cool to room temperature; the ammonia gas flow rate is 1.6-1.8m 3 / h, the flow rate of the infiltrating agent is 3ml / min, and the pressure of ammonia in the nitriding furnace is 0.1MPa; during heat preservation and nitriding, the pressure of the nitriding furnace is 0.5-0.6kPa, and the decomposition rate of ammonia is 40- 50%. Wherein the permeation agent is composed of the following components by weight: 7 parts of methanol, 18 parts of ethanol, 20 parts of ammonium chloride, 10 parts of rare earth elements, 15 parts of ammonium isobutyrate, and 8 part...

Embodiment 2

[0020] The process of nitriding the output shaft of the ring gear includes the following steps: put the parts cleaned with a quick-drying cleaning agent into a nitriding furnace, pre-oxidize at 400°C for 2 hours, and then inject ammonia gas and a permeation agent, And exhaust, heat up to 650°C, the heating time is 30min, then continue to feed ammonia and permeation agent, keep warm at 650°C for 12h, and then air cool to room temperature; the flow rate of ammonia gas is 1.4-1.6m 3 / h, the flow rate of the infiltrating agent introduced is 4ml / min, the pressure of ammonia in the nitriding furnace is 0.05MPa; during heat preservation nitriding, the pressure of the nitriding furnace is 0.4-0.5kPa, and the decomposition rate of ammonia is 60- 70%. Wherein the permeation agent is composed of the following components by weight: 5 parts of methanol, 15 parts of ethanol, 13 parts of ammonium chloride, 8 parts of rare earth elements, and 6 parts of tetrachlorethylene.

[0021] The nitr...

Embodiment 3

[0024] The process of nitriding the output shaft of the ring gear includes the following steps: put the parts cleaned with quick-drying cleaning agent into the nitriding furnace, pre-oxidize at 370°C for 1.5h, and then pass ammonia gas and infiltration agent , and exhaust, heat up to 520°C, the heating time is 30min, then continue to feed ammonia and permeation agent, keep warm and nitriding at 520°C for 18h, and then air cool to room temperature; the flow rate of ammonia gas 1.8-2.0m 3 / h, the flow rate of the infiltrating agent is 2ml / min, the pressure of ammonia in the nitriding furnace is 0.15MPa; during heat preservation nitriding, the pressure of the nitriding furnace is 0.9-1kPa, and the decomposition rate of ammonia is 20-30 %. The permeation agent is composed of the following components in parts by weight: 10 parts of methanol, 20 parts of ethanol, 26 parts of ammonium chloride, 12 parts of rare earth elements, 30 parts of ammonium isobutyrate, and 9 parts of tetrach...

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Abstract

The invention discloses a novel nitriding process. The novel nitriding process comprises the following steps that a cleaned part is placed in a nitride furnace and subjected to preoxidation for 1-2 hours at the temperature of 350-400 DEG C, then ammonia gas and an energizing reagent are injected, exhausting is carried out, the temperature is increased to 520-650 DEG C, then the ammonia gas and the energizing reagent continue to be injected, insulating nitriding is carried out for 12-18 hours at the temperature of 520-650 DEG C, and then the part is cooled to be at the room temperature, specifically, the flow of the injected ammonia gas is 1.4-2.0 m<3> / h, the flow of the injected energizing reagent is 2-4 ml / min, and during insulating nitriding, the pressure of the nitride furnace is 0.4-1.0 kPa, and the ammonia gas resolution ratio is 20%-70%. The nitriding process is simple, the effective hardening layer depth of the obtained part is higher, and the micro-structure of a permeating layer is better; and according to the product subjected to nitriding treatment, deformation is tiny, the dimension precision and the mechanical strength index meet the product design requirements, and perfect combination of the surface hardness, effective hardening layer depth and deformation with the process cycle is achieved.

Description

technical field [0001] The invention belongs to the technical field of nitriding treatment of thin-walled parts, and in particular relates to a novel nitriding process. Background technique [0002] Nitriding treatment refers to a chemical heat treatment process that makes nitrogen atoms penetrate into the surface layer of the workpiece in a certain medium at a certain temperature. Nitrided products have excellent wear resistance, fatigue resistance, corrosion resistance and high temperature resistance. [0003] At present, the nitriding process in the industry is mainly processed by the Bo-type furnace. Even if the commonly used infiltrating agents ammonium chloride, carbon tetrachloride, titanium tetrachloride and rare earth compounds are used, heat treatment is required for about 25 hours in order to achieve a layer depth of 0.3mm. It takes about 40 hours for 0.4mm, and 0.4mm is close to the processing limit of most enterprises at present; some foreign enterprises also u...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/24C23C8/02
CPCC23C8/24C23C8/02
Inventor 周友国陈绍龙杨海龙李福勇蒋西怀
Owner CHONGQING TIEMA IND GRP
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