Ionic nitriding heat treatment process of KMN material

Abstract

The invention discloses an ionic nitriding heat treatment process of a KMN material, and relates to the technical field of metal material heat treatment. When the KMN material is a forge piece, normalizing treatment and thermal refining are conducted firstly, and then ion nitriding treatment is conducted; when the KMN material is a plate or a bar, quenching and tempering are carried out firstly, and then ion nitriding treatment is carried out; wherein the ion nitriding treatment comprises the steps that the temperature ranges from 450 DEG C to 520 DEG C, the nitriding time ranges from 18 hours to 30 hours, the furnace temperature is reduced to 180 DEG C to 220 DEG C, and then discharging and air cooling are conducted. According to the ion nitriding heat treatment process provided by the invention, the core part and the surface of the KMN material subjected to the ion nitriding heat treatment process have high strength and high hardness at the same time, and the bearing capacity of the material is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology for metallic materials, specifically to an ion nitriding heat treatment process for KMN materials. Background Technology

[0002] High-speed, heavy-duty gears made of KMN material not only require high surface hardness, high wear resistance, and corrosion resistance, but also high strength and high hardness in the core. Current technologies cannot achieve a balance between high surface hardness and high wear resistance and high core strength and high hardness in KMN material, thus failing to fully realize the potential of KMN material and limiting its load-bearing capacity.

[0003] Therefore, it is imperative to develop a heat treatment scheme suitable for KMN materials. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an ion nitriding heat treatment process for KMN materials.

[0005] Therefore, in a first aspect, the present invention provides an ion nitriding heat treatment process for KMN material. When the KMN material is a forging, it is first subjected to normalizing and tempering treatment, and then subjected to ion nitriding treatment; when the KMN material is a plate or bar, it is first subjected to the tempering treatment, and then subjected to the ion nitriding treatment; wherein the ion nitriding treatment includes: Temperature 450℃~520℃, nitriding time 18~30 hours, furnace temperature cooled to 180℃~220℃, then removed from the furnace and air cooled.

[0006] Furthermore, the normalizing treatment is carried out at a temperature of 960℃~990℃ for a holding time of (effective thickness of KMN material mm / k1) hours, followed by air cooling; wherein, the value of k1 ranges from 33mm to 40mm.

[0007] Furthermore, the normalizing treatment has a heating rate of 70℃ / h to 100℃ / h.

[0008] Furthermore, the conditioning process includes: Quenching at 950℃~980℃ for a holding time of (effective thickness of KMN material in mm / k2) hours, followed by oil cooling; where k2 ranges from 33mm to 45mm. Tempering, temperature 550℃~610℃, holding time is 1.5~2 times that of quenching holding time, and then cooling in the furnace.

[0009] Furthermore, the quenching temperature is 960℃~970℃, the holding time is (KMN material effective thickness mm / k2) hours, and oil cooling is used; wherein, the value of k2 ranges from 36mm to 42mm; the tempering temperature is 570℃~590℃, and the holding time is 1.5 to 2 times the quenching holding time.

[0010] Furthermore, the quenching heating rate is 70℃ / h~100℃ / h, and the tempering heating rate is 70℃ / h~100℃ / h.

[0011] Furthermore, the ion nitriding treatment is performed at a temperature of 480℃~500℃ for a nitriding time of 20~28 hours.

[0012] Furthermore, after the ion nitriding treatment, the nitriding layer depth of the KMN material is 0.5mm~0.7mm, the surface hardness HV≥700, and the core hardness HB is 290~320.

[0013] In a second aspect, the present invention provides an application of the above-described ion nitriding heat treatment process for KMN materials to process rotating moving parts of compressor KMN materials.

[0014] Furthermore, the rotating moving part is an impeller or a high-speed heavy-duty gear.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: The ion nitriding heat treatment process provided by this invention enables the core and surface of KMN material to have both high strength and high hardness, and significantly improves the load-bearing capacity of the material. Detailed Implementation To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below through specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0016] In a first aspect, this invention provides an ion nitriding heat treatment process for KMN material. When the KMN material is a forging, it undergoes normalizing and tempering treatments first, followed by ion nitriding treatment. When the KMN material is a plate or bar, it undergoes tempering treatment first, followed by ion nitriding treatment. The ion nitriding treatment includes: The temperature is 450℃~520℃, the nitriding time is 18~30 hours, the furnace temperature is cooled to 180℃~220℃, and then the furnace is removed and air-cooled. Preferably, ion nitriding treatment is performed at a temperature of 480℃~500℃ for 20~28 hours.

[0017] In this embodiment of the invention, the chemical composition of the KMN material meets the requirements of the FB13008 standard: C: 0.13%-0.18%; Si: 0.17%-0.37%; Mn: 0.50%-0.80%; Cr: 2.20%-2.50%; Ni≤0.30%; Mo: 0.9%-1.1%; S≤0.015%; P≤0.020%. The ion nitriding heat treatment process provided in this embodiment of the invention enables the KMN material to possess both high strength and high hardness in its core and surface, exhibiting strong surface corrosion resistance and significantly improved load-bearing capacity.

[0018] It is understandable that ion nitriding, as a method of strengthening metal surfaces, utilizes the glow discharge phenomenon to bombard the surface of a part with nitrogen ions generated by the ionization of nitrogen-containing gas, heating and nitriding it to obtain a nitrided surface layer. Currently, there is no ion nitriding process for KMN materials. This invention is applicable to applications requiring high surface hardness, wear resistance, and corrosion resistance, while also demanding high strength and hardness in the core, making it suitable for high-speed, heavy-duty gears. Through ion nitriding, the requirements for high strength and high hardness in both the core and surface are met, significantly improving the material's load-bearing capacity.

[0019] In some embodiments, normalizing treatment is performed at a temperature of 960℃~990℃ for a holding time of (effective thickness of KMN material mm / k) hours, followed by air cooling; wherein, the value of k1 ranges from 33mm to 40mm.

[0020] Optionally, the normalizing treatment heating rate is 70℃ / h~100℃ / h. Controlling the heating rate ensures uniform heating of the inner and outer surfaces of the KMN material workpiece during the heating process, reducing uneven distribution of thermal stress.

[0021] In some embodiments, the conditioning process includes: Quenching is performed at a temperature of 950℃~980℃, with a holding time of (effective thickness of KMN material in mm / k2) hours, followed by oil cooling; where k2 ranges from 33mm to 45mm. Preferably, quenching is performed at a temperature of 960℃~970℃, with a holding time of (effective thickness of KMN material in mm / k2) hours, followed by oil cooling; where k2 ranges from 36mm to 42mm.

[0022] Tempering is performed at a temperature of 550℃~610℃, with a holding time 1.5~2 times that of quenching, followed by furnace cooling. Preferably, tempering is performed at a temperature of 570℃~590℃, with a holding time 1.5~2 times that of quenching.

[0023] Specifically, by tempering, KMN materials can obtain a strong tempered sorbite structure in the core, thereby enhancing the core's mechanical properties and optimizing the microstructure to provide a good foundation for the subsequent formation of the nitrided layer.

[0024] In some embodiments, the quenching heating rate is 70℃ / h~100℃ / h, and the tempering heating rate is 70℃ / h~100℃ / h.

[0025] Specifically, controlling the heating rate during quenching and tempering ensures uniform heating of the inner and outer surfaces of the KMN material workpiece during the heating process, thereby reducing uneven distribution of thermal stress.

[0026] In summary, after the ion nitriding treatment, the nitriding layer depth of the KMN material is 0.5mm~0.7mm, the surface hardness HV≥700, and the core hardness HB is 290~320.

[0027] A second aspect of this invention provides an application of an ion nitriding heat treatment process for KMN materials, used for the treatment of rotating moving parts of compressor KMN materials, including impellers or high-speed heavy-duty gears. Through ion nitriding treatment, the core and surface simultaneously meet the requirements for high strength and hardness, significantly improving the material's load-bearing capacity.

[0028] Example 1: A heat treatment process for KMN material A KMN forging material, the chemical composition by mass percentage includes: C: 0.15%, Si: 0.20%, Mn: 0.62%, Cr: 2.30%, Ni: 0.25%, Mo: 0.9%, S: 0.01%, P: 0.015%.

[0029] The KMN forging material of Example 1 was subjected to heat treatment, including the following steps: (1) Normalizing treatment The temperature was 970℃, the holding time was 3 hours, and then it was air-cooled; the heating rate was 100℃ / h.

[0030] (2) Conditioning treatment First, quench the furnace at a heating rate of 70℃ / h, reaching a temperature of 960℃ and holding for 3.5 hours, followed by oil cooling. Then, temper the furnace at a heating rate of 70℃ / h, reaching a temperature of 580℃ and holding for 5.5 hours, followed by furnace cooling.

[0031] (3) Ion nitriding A glow discharge ion nitriding furnace was used, with a temperature of 510℃ and a nitriding time of 20 hours. The furnace temperature was then cooled to 200℃, and the furnace was then air-cooled after removal from the furnace.

[0032] The mechanical properties and hardness of the KMN forging material after nitriding following the heat treatment process of Example 1 are shown in Tables 1 and 2.

[0033] Example 2: A heat treatment process for KMN material A KMN forging material, the chemical composition by mass percentage includes: C: 0.15%, Si: 0.20%, Mn: 0.62%, Cr: 2.30%, Ni: 0.25%, Mo: 0.9%, S: 0.01%, P: 0.015%.

[0034] The KMN forging material of Example 2 was subjected to heat treatment, including the following steps: (1) Normalizing treatment The temperature was 970℃, the holding time was 3 hours, and then it was air-cooled; the heating rate was 100℃ / h.

[0035] (2) Conditioning treatment First, quench the furnace at a heating rate of 70℃ / h, reaching a temperature of 960℃ and holding for 3.5 hours, followed by oil cooling. Then, temper the furnace at a heating rate of 70℃ / h, reaching a temperature of 580℃ and holding for 5.5 hours, followed by furnace cooling.

[0036] (3) Ion nitriding The process involves using a glow discharge ion nitriding furnace at a temperature of 520℃ for 18 hours, followed by furnace cooling to 200℃, and then air cooling after removal from the furnace.

[0037] The mechanical properties and hardness of the KMN forging material after nitriding following the heat treatment process of Example 2 are shown in Tables 1 and 2.

[0038] Example 3: A heat treatment process for KMN material A KMN forging material, the chemical composition by mass percentage includes: C: 0.16%, Si: 0.20%, Mn: 0.62%, Cr: 2.40%, Ni: 0.25%, Mo: 1.0%, S: 0.01%, P: 0.015%.

[0039] The KMN forging material of Example 3 was subjected to heat treatment, including the following steps: (1) Normalizing treatment The temperature was 980℃, the holding time was 3.5h, and then it was air-cooled; the heating rate was 100℃ / h.

[0040] (2) Conditioning treatment First, quench the material at a heating rate of 70℃ / h, hold it at 970℃ for 4 hours, and then oil cool it. Next, temper the material at a heating rate of 70℃ / h, hold it at 590℃ for 6 hours, and then cool it in the furnace.

[0041] (3) Ion nitriding The process involves using a glow discharge ion nitriding furnace at a temperature of 500℃ for 23 hours, followed by furnace cooling to 200℃ and then air cooling after removal from the furnace.

[0042] The mechanical properties and hardness of the KMN forging material after nitriding following the heat treatment process of Example 3 are shown in Tables 1 and 2.

[0043] Example 4: A heat treatment process for KMN material A KMN forging material, the chemical composition by mass percentage includes: C: 0.16%, Si: 0.20%, Mn: 0.62%, Cr: 2.40%, Ni: 0.25%, Mo: 1.0%, S: 0.01%, P: 0.015%.

[0044] The KMN forging material of Example 4 was subjected to heat treatment, including the following steps: (1) Normalizing treatment The temperature was 980℃, the holding time was 3.5h, and then it was air-cooled; the heating rate was 100℃ / h.

[0045] (2) Conditioning treatment First, quench the material at a heating rate of 70℃ / h, reaching a temperature of 970℃ and holding it for 4 hours, then oil-cool it. Next, temper the material at a heating rate of 70℃ / h, reaching a temperature of 580℃ and holding it for 6 hours, then cool it in the furnace.

[0046] (3) Ion nitriding The process involves using a glow discharge ion nitriding furnace at a temperature of 480℃ for 25 hours, followed by furnace cooling to 200℃ and then air cooling after removal from the furnace.

[0047] The mechanical properties and hardness indicators after nitriding following the heat treatment process of Example 4 are shown in Tables 1 and 2.

[0048] Table 1. Nitriding layer depth and hardness in Examples 1-4

[0049] Table 2 Mechanical properties of Examples 1-4

[0050] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. An ion nitriding heat treatment process for KMN material, characterized in that, When the KMN material is a forging, it is first subjected to normalizing and quenching and tempering, and then to ion nitriding; when the KMN material is a plate or bar, it is first subjected to the quenching and tempering, and then to the ion nitriding; wherein, the ion nitriding includes: Temperature 450℃~520℃, nitriding time 18~30 hours, furnace temperature cooled to 180℃~220℃, then removed from the furnace and air cooled.

2. The ion nitriding heat treatment process for KMN material according to claim 1, characterized in that, The normalizing treatment is performed at a temperature of 960℃~990℃, with a holding time of (effective thickness of KMN material in mm / k1) hours, followed by air cooling; where k1 ranges from 33mm to 40mm.

3. The ion nitriding heat treatment process for KMN material according to claim 2, characterized in that, The normalizing treatment involves a heating rate of 70℃ / h to 100℃ / h.

4. The ion nitriding heat treatment process for KMN material according to claim 1, characterized in that, The conditioning process includes: Quenching at 950℃~980℃ for a holding time of (effective thickness of KMN material in mm / k2) hours, followed by oil cooling; where k2 ranges from 33mm to 45mm. Tempering, temperature 550℃~610℃, holding time is 1.5~2 times that of quenching holding time, and then cooling in the furnace.

5. The ion nitriding heat treatment process for KMN material according to claim 4, characterized in that, The quenching process is carried out at a temperature of 960℃~970℃, with a holding time of (KMN material effective thickness mm / k2) hours, and is performed by oil cooling; wherein, the value of k2 ranges from 36mm to 42mm. The tempering is performed at a temperature of 570℃~590℃, and the holding time is 1.5~2 times that of the quenching holding time.

6. The ion nitriding heat treatment process for KMN material according to claim 4 or 5, characterized in that, The quenching heating rate is 70℃ / h~100℃ / h, and the tempering heating rate is 70℃ / h~100℃ / h.

7. The ion nitriding process for KMN material according to claim 1, characterized in that, The ion nitriding treatment is performed at a temperature of 480℃~500℃ for a nitriding time of 20~28 hours.

8. The ion nitriding heat treatment process for KMN material according to claim 1, characterized in that, After the ion nitriding treatment, the nitriding layer depth of the KMN material is 0.5mm~0.7mm, the surface hardness HV≥700, and the core hardness HB is 290~320.

9. The application of the ion nitriding heat treatment process for the KMN material according to any one of claims 1 to 8, characterized in that, Rotating moving parts used to process KMN materials for compressors.

10. The application according to claim 9, characterized in that, The rotating moving part is an impeller or a high-speed heavy-duty gear.

Images