CN106755772B - Softening method for non-carburized region of CSS-42L gear steel - Google Patents
Softening method for non-carburized region of CSS-42L gear steel Download PDFInfo
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- CN106755772B CN106755772B CN201611097538.4A CN201611097538A CN106755772B CN 106755772 B CN106755772 B CN 106755772B CN 201611097538 A CN201611097538 A CN 201611097538A CN 106755772 B CN106755772 B CN 106755772B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
- C21D1/773—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material under reduced pressure or vacuum
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/04—Hardening by cooling below 0 degrees Celsius
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/32—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for gear wheels, worm wheels, or the like
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2261/00—Machining or cutting being involved
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Abstract
The invention relates to a softening method of a non-carburized region of CSS-42L gear steel, which is characterized in that high-temperature austenite is completely converted into super-cooled austenite in a matrix structure of the non-carburized region after carburization, sub-temperature annealing and quenching, the hardness is only HRC 28-35, and the mechanical cutting processing is facilitated. By adopting the process adjusting scheme, the processing difficulty of the non-carburized area of the CSS-42L carburized part is greatly reduced, and the subsequent mechanical semi-finishing and fine processing are facilitated.
Description
Technical Field
The invention relates to a softening method of a non-carburized region, in particular to a softening method of a non-carburized region of CSS-42L gear steel.
Background
Aiming at the ultrahigh requirement of an aviation heavy-duty transmission system on the temperature resistance of gears, the US develops CSS-42L third-generation carburized gear steel which has the remarkable characteristics of good high-temperature red hardness and high-temperature tempering resistance, after carburization quenching, the carburized and quenched steel is still in service at 427 ℃ for 500 hours, the hardness of a carburized layer tissue is still maintained above HRC60, and the dry friction and wear resistance is excellent.
After traditional gear carburizing, sub-temperature annealing, quenching, cold treatment and tempering, semi-finishing and finish machining are needed to be carried out on a non-carburized area, but after the CSS-42L gear steel is subjected to carburizing, sub-temperature annealing, quenching, cold treatment and aging tempering, the hardness of the non-carburized area is as high as HRC 45-55, mechanical semi-finishing and finish machining difficulty is extremely high, cutter wear is serious, production efficiency is greatly reduced, and the situation is solved by a relevant literature report at present.
Disclosure of Invention
The invention aims to provide a softening method for a non-carburized area of CSS-42L gear steel, which is characterized in that the non-carburized area of the CSS-42L gear steel after carburization and quenching is softened by adjusting a heat treatment process route after carburization, the hardness is reduced to HRC 28-35, and subsequent mechanical semi-finishing and finish machining are facilitated.
The adopted process adjustment scheme is as follows:
1. after carburizing the CSS-42L gear steel, directly placing the gear steel in a vacuum oil quenching furnace for high-temperature austenitizing without performing sub-temperature annealing, wherein the austenitizing temperature is 1050-1200 ℃, and after preserving the heat for 0.5-6 h, performing vacuum oil quenching, wherein the temperature of a quenching oil bath is 40-75 ℃;
2. after oil quenching, stress relief treatment is carried out at 100-300 ℃, and the stress relief time is 1-10 h;
3. after stress is eliminated, the non-carburized area is machined;
4. after the mechanical cutting processing of the non-carburized area is finished, carrying out cold treatment on the whole part at minus 180-minus 70 ℃ for 2-10 h;
5. and after cold treatment, transferring the part to a vacuum furnace for aging treatment, or performing aging treatment on the surface of the part after copper plating by using a controlled atmosphere furnace, wherein the aging treatment temperature is 466-526 ℃, and the aging time is 1-8 h.
Because the alloy content of the CSS-42L material exceeds 30 wt.%, after the part is carburized, annealed at a sub-temperature and quenched, high-temperature austenite is completely converted into super-cooled austenite in a matrix structure of a non-carburized region, the hardness is only HRC 28-35, and the mechanical cutting processing is facilitated. Although the carburized region of the part is also a low hardness, super-cooled austenite structure at this time, this super-cooled austenite structure is more stable. After the non-carburized area is mechanically cut, the part is subjected to cold treatment, supercooled austenite can be converted into a quenched martensite structure, the hardness of a carburized layer structure of the carburized area and a matrix structure of the non-carburized area is greatly improved, and the hardness of the carburized area and the non-carburized area is restored to the hardness index of the original process (carburizing, sub-temperature annealing, quenching, cold treatment and aging tempering) through high-temperature aging secondary hardening. By adopting the process adjusting scheme, the processing difficulty of the non-carburized area of the CSS-42L carburized part is greatly reduced, and the subsequent mechanical semi-finishing and fine processing are facilitated.
Detailed Description
A softening method of a non-carburized area of CSS-42L gear steel comprises the following steps:
1. after carburizing the CSS-42L gear steel, directly placing the gear steel in a vacuum oil quenching furnace for high-temperature austenitizing without performing sub-temperature annealing, wherein the austenitizing temperature is 1050-1200 ℃, and after preserving the heat for 0.5-6 h, performing vacuum oil quenching, wherein the temperature of a quenching oil bath is 40-75 ℃;
2. after oil quenching, stress relief treatment is carried out at 100-300 ℃, and the stress relief time is 1-10 h;
3. after stress is eliminated, the non-carburized area is machined;
4. after the mechanical cutting processing of the non-carburized area is finished, carrying out cold treatment on the whole part at minus 180-minus 70 ℃ for 2-10 h;
5. and after cold treatment, transferring the part to a vacuum furnace for aging treatment, or performing aging treatment on the surface of the part after copper plating by using a controlled atmosphere furnace, wherein the aging treatment temperature is 466-526 ℃, and the aging time is 1-8 h.
Examples
The gear part for some aviation transmission system is made of CSS-42L gear steel, and after the tooth surface of the part is carburized, the hardness of a non-carburized area is HRC 51.8. The non-carburized region needs to be subjected to mechanical cutting processing subsequently, so the non-carburized region needs to be softened, and the specific steps are as follows:
1. after carburization, the part is directly placed in a vacuum oil quenching furnace for high-temperature austenitization without sub-temperature annealing, wherein the austenitizing temperature is 1100 ℃, and after heat preservation is carried out for 2 hours, vacuum oil quenching is carried out, and the quenching oil bath temperature is 55 ℃;
2. after oil quenching, stress relief treatment is carried out at 200 ℃, and the stress relief time is 4 h;
3. after stress is eliminated, the non-carburized area is machined;
4. after the mechanical cutting processing of the non-carburized area is finished, carrying out cold treatment on the whole part at-180 ℃ for 4 h;
5. after cold treatment, the part is transferred to a vacuum furnace for aging treatment, wherein the aging treatment temperature is 496 ℃, and the aging time is 4 h.
The technological scheme is adjusted and optimized by the method, the hardness of a non-carburized area after carburization and vacuum oil quenching is HRC31.2, and the cutting performance is greatly improved; meanwhile, cold treatment is carried out after processing, so that the hardness of the non-carburized area is restored to the original process index, and the design requirement is met.
Claims (1)
1. A softening method of a non-carburized area of CSS-42L gear steel is characterized by comprising the following steps:
1) after carburizing the CSS-42L gear steel, directly placing the gear steel in a vacuum oil quenching furnace for high-temperature austenitizing without performing sub-temperature annealing, wherein the austenitizing temperature is 1050-1200 ℃, and after preserving the heat for 0.5-6 h, performing vacuum oil quenching, wherein the temperature of a quenching oil bath is 40-75 ℃;
2) after oil quenching, stress relief treatment is carried out at 100-300 ℃, and the stress relief time is 1-10 h;
3) after stress is eliminated, the non-carburized area is machined;
4) after the mechanical cutting processing of the non-carburized area is finished, carrying out cold treatment on the whole part at minus 180-minus 70 ℃ for 2-10 h;
5) and after cold treatment, transferring the part to a vacuum furnace for aging treatment, or performing aging treatment on the surface of the part after copper plating by using a controlled atmosphere furnace, wherein the aging treatment temperature is 466-526 ℃, and the aging time is 1-8 h.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611097538.4A CN106755772B (en) | 2016-12-02 | 2016-12-02 | Softening method for non-carburized region of CSS-42L gear steel |
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|---|---|---|---|
| CN201611097538.4A CN106755772B (en) | 2016-12-02 | 2016-12-02 | Softening method for non-carburized region of CSS-42L gear steel |
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| CN106755772A CN106755772A (en) | 2017-05-31 |
| CN106755772B true CN106755772B (en) | 2021-03-19 |
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| CN109182696B (en) * | 2018-11-21 | 2021-11-05 | 中国航发哈尔滨东安发动机有限公司 | Nitriding surface modification method for third-generation carburized steel material |
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