KR100240042B1 - High temperature nitro-carbonizing treatment of metal - Google Patents

Abstract

칭한후, 이를 다시 가열하여 공석점부근인 600∼740℃ 사이의 오스테나이트 구역에서 일산화탄소(Co)와, 질소(N2), 수소(H2)를 적당량 혼합한 변성가스(GAS)와, 프로판가스(C3H8) 등 중탄화수소가스(CmHn계), 그리고 질화가스(NH3)를 적합한 중량비로 혼합한 분위기가스를 열처리노 내부에 투입하여 열처리 함으로서, 금속의 표면에 10∼50㎛의 ε-질화물과 탄화물이 동시에 생성되는 약간의 세멘타이트가 포함된 화합물층을 형성하고, 그 아래에 경화된 미세립 베이나이트 조직과 템퍼된 마르텐사이트 조직을 이루도록 함으로서, 상기한 바와같이 본 발명은 금속의 표면에 10∼50㎛의 ε-질화물과 탄화물이 동시에 생성되는 약간의 세멘타이트가 포함된 화합물층을 형성하여, 표면의 색상이 회색이거나, 회청색으로 깨끗하여 최종 완성품으로 사용이 가능하며, 외관의 조도를 향상시키기 위하여 래핑을 하거나 표면에 Fe3O4가 생성되도록 검게 산화시키고 오일을 분사하면, 종래 내식성을 향상시키기 위하여 파카 라이징이나 전착도장, 크롬, 아연, 니켈도금 하던 공정을 생략할 수 있는 것은 물론, 화합물층 아래에 질소와 탄소의 확산으로 오스테나이트의 형성을 촉진시킨 후, 기름이나 수용성냉매, 물, 염욕 등의 냉매를 이용하여 켄칭함으로서, 경화된 미세립 베이나이트 조직과 템퍼된 마르텐사이트 조직을 갖도록 하여 고하중에 의한 마모와 박리를 방지하며, 찍힘 윤활 등에 좋은 효과를 발휘하도록 한 것이다.The present invention is intended to diffuse nitrogen and carbon on the surface of the metal, mild carburizing and carburizing nitriding at high temperature, mild steel, low carbon steel, high carbon steel, alloy steel, titanium (Ti) or vanadium (V), chromium (Cr) Metals such as steel, molybdenum aluminum (Mo-Al) steel, sintered products, and castings in the austenitic zone at 600 to 740 ° C near the vacancy point, carbon monoxide (Co), nitrogen (N2), hydrogen ( Into a heat treatment furnace, an atmosphere gas in which a suitable amount of modified gas (GAS), propane gas (C3H8), carbon dioxide (CmHn), and nitride gas (NH3) is mixed in an appropriate weight ratio On the surface of the metal to form a compound layer containing a small amount of cementite in which ε-nitrides and carbides of 10 µm to 50 µm are simultaneously formed, and at the same time to form a hardened fine grain bainite structure and a tempered martensite structure. High temperature carbonization of a metal The method relates to a primary carburizing treatment at a high temperature of 850 to 960 ° C, or to a modified gas of ammonia gas (MB) 0.5 to 5 vol.% (V)% and CO-N2-H2, CmHn system at 700 to 900 ° C. After entering the mixed gas, the temperature is reduced after general carburizing and nitriding treatment, and 25-65 volume (V)% of ammonia gas, modified gas of CO-N2-H2 and mixed gas of CmHn system are located near the vacancy point (600-740 ° C). Nitride treatment is carried out by inputting, and the treated material is mild steel, low carbon steel, high carbon steel, alloy steel, titanium (Ti), vanadium (V), chromium (Cr) containing steel, and molybdenum aluminum (Mo-Al). ) Steels, sintered products, castings, etc., and as a result of the treatment, 10 to 50 µm ε-nitrides and carbides are prepared at the surface layer portion, and hardened fine grain bainite structure and martensite structure under the compound layer; Mild steel, low carbon steel, high carbon steel, alloy, primary carburized and carburized at high temperature , Titanium (Ti) and vanadium (V), chromium (Cr), a steel, molybdenum, aluminum (Al-Mo) steel, sinter, to ronaeng a metal such as castings or containing

After it is heated, it is heated again and modified gas (GAS) and propane gas (CoS), nitrogen (N2) and hydrogen (H2) mixed in an appropriate amount in the austenite zone at 600 to 740 ° C near the vacancy point. Atmospheric gas mixed with heavy hydrocarbon gas (CmHn) such as C3H8) and nitride gas (NH3) in a suitable weight ratio is introduced into a heat treatment furnace and subjected to heat treatment. By forming a compound layer containing some cementite produced at the same time and forming a hardened fine grain bainite structure and a tempered martensite structure thereunder, as described above, the present invention provides 10 to 50 탆 on the surface of the metal. It forms a compound layer containing some cementite that ε-nitride and carbide of is produced simultaneously, and the surface of the surface is gray or grayish blue and can be used as a final product. In order to improve the roughness, blackening and oxidizing to produce Fe3O4 on the surface and spraying oil, it is possible to omit the process of parkarizing, electrodeposition coating, chromium, zinc, nickel plating in order to improve the corrosion resistance, The formation of austenite is promoted by diffusion of nitrogen and carbon under the compound layer, followed by quenching with refrigerants such as oil, water-soluble refrigerants, water, and salt bath, thereby hardening the fine grain bainite structure and the tempered martensite structure. It is intended to prevent wear and peeling due to high loads, and to exert a good effect on lubrication.

Description

High temperature nitriding treatment of metal

The present invention is intended to diffuse nitrogen and carbon on the surface of the metal, mild carburizing and carburizing nitriding at high temperature, mild steel, low carbon steel, high carbon steel, alloy steel, titanium (Ti) or vanadium (V), chromium (Cr) Metals such as steel, molybdenum aluminum (Mo-Al) steel, sintered products and castings, etc., are used in the austenite zone at 600 to 740 ° C near the vacancy point, and carbon monoxide (Co), nitrogen (N2) and hydrogen ( Into a heat treatment furnace, an atmosphere gas in which a suitable amount of modified gas (GAS), propane gas (C3H8), and carbon dioxide gas (CmHn) and nitride gas (NH3) are mixed in an appropriate weight ratio On the surface of the metal to form a compound layer containing a little cementite containing ε-nitride and carbide of 10 ㎛ to 50 ㎛ at the same time, while forming a hardened fine grain bainite and a tempered martensite High Temperature Nitriding of One Metal It relates to a treatment method.

Conventional metal nitridation treatment improves wear resistance by forming a layer of nitride carbide and epsilon (ε) on the surface at 440 ~ 650 ℃, or improves corrosion resistance by oxidizing on the compound layer. In order to prevent this, the hardness was sharply lowered, so that heat treatment was performed at a low temperature for a long time (6 hours to 90 hours), or nitriding steels containing chromium (Cr) and aluminum (Al) were selected.

Therefore, in the heat treatment processing of automotive parts or general mechanical parts, it was processed at high temperature to compensate for the impact and tensile strength, which is a disadvantage of low temperature nitriding products. In particular, when heat treatment of the plate, the press tempering treatment to correct the heat deformation.

In view of the above-mentioned problems, the present invention provides carbon monoxide (Co), nitrogen (N2), and hydrogen (H2) in the austenite zone at 600 to 740 ° C near the vacancy point. Atmospheric gas of 10 to 50 µm was introduced into the surface by adding a modified gas (GAS), propane gas (C3H8), heavy hydrocarbon gas (CmHn system), and nitride gas (NH3) in an appropriate weight ratio. A compound layer containing some cementite containing ε-nitride and carbide was formed at the same time, while at the same time forming a hardened fine grain bainite structure and a tempered martensite structure.

Referring to the present invention in more detail as follows.

Primary carburizing treatment at a high temperature of 850 to 960 ° C, or 0.5 to 5 volumes (V)% of ammonia gas (NH3), a modified gas of CO-N2-H2, and a mixed gas of CmHn type were introduced at 700 to 900 ° C. After the general carburizing and nitriding treatment, the temperature is lowered and the nitriding treatment is performed by introducing 25-65 volume (V)% of ammonia gas, modified gas of CO-N2-H2 and mixed gas of CmHn system near the vacancy point (600-740 ℃). As material for processing, mild steel, low carbon steel, high carbon steel, alloy steel, titanium (Ti), vanadium (V), chromium (Cr) -containing steel, molybdenum aluminum (Mo-Al) steel, and sintered products As a result of the treatment, ε-nitrides and carbides having a thickness of 10 to 50 µm are produced in the surface layer portion, and at the same time, they form a hardened fine grain bainite structure and martensite structure directly under the compound layer, or primary carburization at a high temperature. And carburized nitriding, mild steel, low carbon steel, high carbon steel, alloy steel, titanium (Ti) or bars After quenching or quenching metals such as Na (V), chromium (Cr), molybdenum aluminum (Mo-Al) steel, sintered products, castings, etc. Heavy hydrocarbon gas (CmHn), such as modified gas (GAS), propane gas (C3H8), and nitriding, containing an appropriate amount of carbon monoxide (Co), nitrogen (N2), and hydrogen (H2) in an austenite zone at 740 ° C. By heat-treating the atmosphere gas mixed with the gas (NH 3) in a suitable weight ratio inside the heat-treatment furnace, a compound layer containing some cementite containing 10-50 μm ε-nitride and carbide simultaneously on the surface of the metal is formed. And a hardened fine grain bainite structure and a tempered martensite structure beneath it.

In addition, a modified gas (GAS) and propane gas (C3H8) in which an appropriate amount of carbon monoxide (Co), nitrogen (N2), and hydrogen (H2) are mixed in the austenite zone at 600 to 740 ° C near the vacancy point as described above. Atmospheric gas mixed with heavy hydrocarbon gas (CmHn) and nitride gas (NH3) in a suitable weight ratio is introduced into a heat treatment furnace, and heat treated by simultaneously heating 10-50 μm ε-nitride and carbide on the surface of the metal. By forming a compound layer containing a small amount of cementite produced, and promoting the formation of austenite by diffusion of nitrogen and carbon under it, and then quenching using a refrigerant such as oil, water-soluble refrigerant, water, salt bath, The surface of the compound layer may be cured by having a hardened fine grain bainite structure and a tempered martensite structure.

In the austenite zone at 600 to 740 ° C., heavy hydrocarbon gas such as modified gas (GAS), propane gas (C3H8), and a mixture of carbon monoxide (Co), nitrogen (N 2), and hydrogen (H 2) in an appropriate amount, CmHn-based) and a small amount of cementite in which 10 to 50 µm ε-nitride and carbide are simultaneously formed on the surface of the metal by injecting an atmosphere gas mixed with nitride gas (NH 3) in an appropriate weight ratio into the heat treatment furnace. After forming a compound layer containing, and formed under the hardened fine grain bainite structure and tempered martensite structure, the surface is oxidized with air or steam to produce Fe304, or as described above 600 ~ 740 ℃ Heavy hydrocarbon gas (CmHn) such as modified gas (GAS), propane gas (C3H8), and nitride gas (CoS) containing nitrogen monoxide (Co), nitrogen (N2) and hydrogen (H2) in an austenite zone between them. Mix NH3) in suitable weight ratio Injecting the atmosphere gas into the heat treatment furnace and performing heat treatment to form a compound layer containing some cementite on the surface of the metal, which simultaneously produces 10-50 μm of nitride and carbide, and cured fine grain bainite After the formation of the tempered martensitic tissue with the tissue, the surface may be wrapped to improve roughness to oxidize the surface with air or water vapor at between 450 and 650 ° C. to produce Fe 3 O 4.

Thus, the subjects treated with the present invention, the color of the surface is gray or gray-blue, and can be used as the final finished product, it is wrapped or blackened to produce Fe3O4 on the surface to improve the roughness of the oil and oil When spraying, in order to improve the corrosion resistance of the prior art, it is possible to omit the process of the coating, electrodeposition coating, chromium, zinc, nickel plating.

In order to implement the above-described present invention, it is possible to use all the heat treatment furnaces developed and used so far, such as a general all-case furnace, a vertical furnace, a box type, a pit, a continuous furnace, etc. And a common agitating fan, or a single and both agitating pans capable of adjusting the flow rate in the quenching chamber, a variety of gas lines to match the atmosphere inside the furnace, and a heating device and temperature control to maintain a constant temperature. It is ideal to install a device and install ammonia helido meter and instruments capable of O2 and Co2 analysis.

Illustrating the test cases of the present invention described above are as follows.

1) The high-temperature nitriding of ψ240 automobile disk assay plate (DISK ASS'Y PLATE) made of general mild steel (SHPI, SPCC, SPHC) with the present invention, assembling as it is, durability test 3 million times Passed the STOPPER TORQUE test and there was no damage, so it was decided that it could be applied immediately.

Therefore, it is possible to omit the hot press tempering process, which has been essential to prevent thermal deformation during the high temperature carbonization treatment of automotive disk assay plates.

2) As a result of inspecting the gear and sleeve which is a part of the transmission part of automobile by high temperature nitriding with the present invention, the surface hardness and hardening depth are the same as those of the existing carburized materials, while the tooth carburized materials have a tooth change of 50㎛. The treatment according to the present invention had a tooth change of 15 µm, which was excellent in the treatment according to the present invention.

3) When the washer material of S45C was carburized by the conventional method, the degree of deformation in the plan view was 0.25 to 0.42 µm, and the surface hardness was about Hv760 to 840 when the high temperature carbonization treatment was performed for about 5 hours according to the present invention. (Hv550) Depth of 0.3mm or more has sufficient abrasion resistance, and the internal hardness is not only the same as that of the existing carburizing and nitriding at about Hv200, but also the deformation degree in plan view is 0.05 to 0.10mm, so that the post-processing treatment is omitted. It became.

As described above, the present invention forms a compound layer containing some cementite on which the surface of the metal simultaneously forms 10-50 μm ε-nitride and carbides, and the surface of the surface is grayish, but it is grayish blue and clean. It can be used as a finished product, and when it is wrapped or black oxidized to produce Fe304 on the surface to improve the roughness of the surface, and sprays oil, it is possible to improve the corrosion resistance of conventional coatings such as parkaizing or electrodeposition coating, chromium, zinc, nickel plating. The step can be omitted, as well as the formation of austenite by the diffusion of nitrogen and carbon under the compound layer, and then quenched using a refrigerant such as oil, water-soluble refrigerant, water, salt bath, etc. It has nit structure and tempered martensite structure to prevent abrasion and peeling by high load, and is good for lubrication And it exerts.

In addition, the interior of the treated product is a composite deep tissue-ferrite configuration, which is maintained as the hardness of the raw material, thereby having a ductility of the material.

Selective use of some steel grades (0.35 to 0.55% carbon steel) can provide good properties, especially where high internal strength and long wear resistance are required, and can be used to replace expensive alloy hardened steels with low-cost carbon / manganese steel. .

In addition, when steel containing 0.15 ~ 0.25% of titanium (Ti) is used, wear resistance, fatigue resistance and impact resistance are always more increased due to the hardness of the surface layer, and compared with the conventional surface hardening method in the deformation after heat treatment of the treated product. Very small, in particular, the lower the quenching temperature can lead to a reduction in the amount of deformation.

Nitrogen and carbon are abundant in the layer directly below the compound layer, and the curing ability is excellent, and quenching at low temperature is possible.

This has the advantage of being applicable to non-alloyed steel and mild steel.

It can also contribute to reducing strain by stirring speed and method when quenching in oil (other quenching refrigerants described above).

It is possible to predict dimensional change by treatment temperature and time, agitation speed, and method, so it is reproducible and mass-produced, and deformation as much as the thickness of layer is generated. This is possible.

In addition, for products that are stress-removed between 600 and 740 ° C after quenching the roughened product at 900 ° C by air cooling or furnace cooling, high-quality nitriding carbonization is performed after finishing heat treatment in consideration of dimensional change after heat treatment. It is a new and useful invention that can be assembled and used immediately because it can be produced.

Claims (4)

Primary carburizing treatment at a high temperature of 850 to 960 ° C, or 0.5 to 5 volumes of ammonia gas (NH3), modified gas of CO-N2-H2, mixed gas of CmHn system at 700 to 900 ° C After the general carburizing and nitriding treatment, the temperature is lowered and the nitriding treatment is performed by introducing 25-65 volume (V)% of ammonia gas, modified gas of CO-N2-H2, and mixed gas of CmHn system near the vacancy point (600-740 ° C). As materials for processing, mild steel, low carbon steel, high carbon steel, alloy steel, titanium (Ti), vanadium (V), chromium (Cr) -containing steel, molybdenum aluminum (Mo-Al) steel, and sintered products As a result of the treatment, as a result of the treatment, a high-temperature nitriding treatment of a metal for producing 10-50 µm ε-nitride and carbide at the surface layer portion and forming a fine grain bainite structure and martensite structure cured directly under the compound layer In the method, austenite between 600 and 740 ° C. near the vacancy point. At the station, carbon dioxide (Co), nitrogen gas (N2), hydrogen gas (H2), a mixture of moderate gas (GAS), propane gas (C3H8), such as heavy hydrocarbon gas (CmHn-based), and nitrogen gas (NH3) 25 A compound layer containing a small amount of cementite which simultaneously produces 10-50 μm of ε-nitride and carbide on the surface of the metal by injecting an atmosphere gas mixed at a volume (V)% of ˜65% into the heat treatment furnace. And promote the formation of austenite by diffusion of nitrogen and carbon under it, and then quenching with refrigerant such as oil, water-soluble refrigerant, water, salt bath, etc. A method for high temperature nitriding of metals, wherein the surface of the compound layer is hardened by having a tempered martensite structure. Mild steel, low carbon steel, high carbon steel, alloy steel, titanium (Ti) or vanadium (V), chromium (Cr) -containing steel, molybdenum aluminum (Mo-Al) steel, small After quenching or quenching metals such as shorts and castings, they are heated again and carbon monoxide (Co), nitrogen (N2) and hydrogen (H2) in the austenite zone between 600 and 740 ° C near the vacancy point. ), An atmosphere gas containing a mixture of modified gas (GAS), propane gas (C3H8), heavy hydrocarbon gas (CmHn), and nitride gas (NH3) at a volume (V) of 25 to 65%. Injecting and heat-treating inside to form a compound layer containing a small amount of cementite in which 10- 50 µm ε-nitride and carbide are simultaneously formed on the surface of the metal, and hardened microstructured bainite structure and tempered thereunder. Hot nitriding of metals, characterized by martensitic structure Way. The modified gas (GAS) and propane gas (3) according to claim 1, wherein an appropriate amount of carbon monoxide (Co), nitrogen (N2), and hydrogen (H2) is mixed in an austenite zone at 600 to 740 ° C near the vacancy point. 10 to 50 is applied to the surface of the metal by injecting and heat-treating an atmosphere gas containing a mixture of heavy hydrocarbon gas (CmHn) such as C3H8) and nitride gas (Nm3) at a volume (V) of 25 to 65%. Form a compound layer containing a small amount of cementite, which simultaneously produces ε-nitrides and carbides of μm, and underneath forms a hardened fine grain bainite structure and a tempered martensite structure, and then surface the surface with air or water vapor. A method for high temperature nitrification of a metal, characterized in that the oxidation to form Fe304. 4. The modified gas (GAS) and propane gas (CG) and propane gas according to claim 3, wherein an appropriate amount of carbon monoxide (Co), nitrogen (N2), and hydrogen (H2) is mixed in an austenite zone at about 600 to 740 ° C near the vacancy point. 10 to 50 nm on the surface of the metal by injecting and heat-treating the atmosphere gas mixed with heavy hydrocarbon gas (CmHn-based) such as C3H8) and nitride gas (NH3) at a volume (V) of 25 to 65%. To form a compound layer containing a small amount of cementite which simultaneously produces ε-nitride and carbide of, and then hardened fine grain bainite tissue and tempered martensite tissue, and then the surface is wrapped to improve roughness To oxidize the surface with air or steam at between 450 and 650 ° C. to produce Fe 3 O 4.