KR100998055B1 - Heat treatment method for salt bath carburization of stainless steel having high corrosion resistance - Google Patents
Heat treatment method for salt bath carburization of stainless steel having high corrosion resistance Download PDFInfo
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- KR100998055B1 KR100998055B1 KR1020080098695A KR20080098695A KR100998055B1 KR 100998055 B1 KR100998055 B1 KR 100998055B1 KR 1020080098695 A KR1020080098695 A KR 1020080098695A KR 20080098695 A KR20080098695 A KR 20080098695A KR 100998055 B1 KR100998055 B1 KR 100998055B1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/40—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions
- C23C8/42—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions only one element being applied
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- C23C8/46—Carburising of ferrous surfaces
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- 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
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- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
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Abstract
본 발명은 스테인리스강(Stainless Steel) 및 Fe-Cr-Ni계 합금의 경도, 피로강도, 내마모성 및 내식성을 향상시키는 표면경화(Case Hardening) 공정에 관한 것이다.The present invention relates to a surface hardening process for improving the hardness, fatigue strength, wear resistance and corrosion resistance of stainless steel and Fe-Cr-Ni-based alloys.
즉, 본 발명은 피-침탄제품을 염산 욕에 침지시켜 표면의 부동태 피막을 제거하는 공정과, 시안화나트륨(NaCN)이 주성분인 염에 염화물과 탄산나트륨(Na2CO3)의 탄산염을 가한 염욕에 피-침탄제품을 침지시켜 400℃~550℃에서 10~70시간 동안 시안화나트륨(NaCN)의 분해로 생긴 탄소원자에 의한 침탄을 행하는 공정과, 침탄층 표면에 생성된 산화 스케일 및 스머트(Smut) 형상의 흑색 피막을 질산을 사용하여 화학에칭으로 제거하여 침탄된 제품이 공기와 접촉하여 부동태화되도록 한 것을 특징으로 한다.That is, the present invention is to remove the passivation film on the surface by immersing the carburized product in a hydrochloric acid bath, and to a salt bath in which chloride and sodium carbonate (Na 2 CO 3 ) are added to a salt whose main component is sodium cyanide (NaCN). Immersing the carburized product and carburizing with carbon atoms resulting from decomposition of sodium cyanide (NaCN) for 10 to 70 hours at 400 ° C. to 550 ° C., and oxidizing scale and smut generated on the surface of the carburized layer. The black film having the shape of) is removed by chemical etching using nitric acid, so that the carburized product is passivated by contact with air.
상기와 같은 본 발명에 의하면 관 이음쇠의 후위 페룰, 슬리브, 밸브 시트, 볼트, 너트 및 스크루 등에 사용되는 스테인리스강을 포함하는 Fe-Cr-Ni계 합금의 표면경도 및 내마모성을 향상시킴과 동시에 부식을 방지하는 효과가 있으며, 316 · 316L · 304 · 304L 스테인리스강 및 Incoloy 825 · Inconel 600 · Hastelloy C-276 등의 Fe-Cr-Ni계 합금에 적용할 수도 있는 것이다.According to the present invention as described above to improve the surface hardness and wear resistance of the Fe-Cr-Ni-based alloy including stainless steel used in the rear ferrules, sleeves, valve seats, bolts, nuts and screws of the pipe fittings and at the same time corrosion It is effective in preventing and can be applied to Fe-Cr-Ni alloys such as 316, 316L, 304, 304L stainless steel, Incoloy 825, Inconel 600, Hastelloy C-276 and the like.
스테인리스강의 염욕 침탄 열처리 방법, 고내식성, 시안화나트륨, 침탄, 부식방지 Salt bath carburizing heat treatment method of stainless steel, high corrosion resistance, sodium cyanide, carburizing, corrosion prevention
Description
본 발명은 고내식성을 갖는 스테인레스강의 염욕 침탄 열처리 방법에 관한 것으로서, 더욱 상세히는 스테인리스강(Stainless Steel) 및 Fe-Cr-Ni계 합금의 경도, 피로강도, 내마모성 및 내식성을 향상시키는 표면경화(Case Hardening) 공정에 관한 것이다.The present invention relates to a salt bath carburizing heat treatment method of stainless steel having high corrosion resistance, and more particularly, surface hardening (Case) to improve hardness, fatigue strength, abrasion resistance, and corrosion resistance of stainless steel and Fe-Cr-Ni-based alloys. Hardening) process.
스테인리스강(특히, 오스테나이트계 스테인리스강)은 우수한 내식성, 연성 및 비자성 특성 때문에 식품 · 화학 플랜트 · 해양 플랜트 · 원자력 · 반도체 산업분야의 기계부품으로 널리 사용되고 있다.Stainless steels (particularly austenitic stainless steels) are widely used as mechanical components in the food, chemical, marine, nuclear, and semiconductor industries because of their excellent corrosion resistance, ductility, and nonmagnetic properties.
그러나 오스테나이트계 스테인리스강은 탄소강(Carbon Steel)에 비해 낮은 경도 때문에 강도 및 내마모성이 좋지 않다는 단점을 가지고 있다.However, austenitic stainless steel has a disadvantage in that its strength and abrasion resistance are not good because of its lower hardness than carbon steel.
침탄이나 질화 같은 표면경화 공정은 탄소강의 내마모성을 향상시키는 데는 매우 효과적이지만, 오스테나이트계 스테인리스강에 적용시키는 데는 제한이 있다.Surface hardening processes such as carburization and nitriding are very effective in improving the wear resistance of carbon steels, but have limitations in their application to austenitic stainless steels.
즉 오스테나이트계 스테인리스강 내부로 질소 · 탄소원자를 확산 침투시키기 위해서는 비교적 고온인 550℃ 이상에서 열처리를 행한다. 이때 표면에 질화물 · 탄화물이 생성되어 석출경화에 의해 경도가 증가하면서 내마모성이 향상되지만, 이온도범위에서는 크롬-질화물(Chromium Nitride) · 크롬-탄화물(Chromium-Carbide)이 석출되어 강재 내부에 고용된 크롬원자를 고갈시켜 내식성을 떨어뜨리는 문제점을 야기하게 된다.In other words, in order to diffuse and penetrate nitrogen and carbon atoms into the austenitic stainless steel, heat treatment is performed at a relatively high temperature of 550 ° C. or higher. At this time, nitrides and carbides are formed on the surface, and the hardness is increased by precipitation hardening, and wear resistance is improved. However, in the range of ionicity, chromium-nitride and chromium-carbide are precipitated and dissolved in steel. Depletion of chromium atoms causes a problem of lowering the corrosion resistance.
표면경화는 금속 제품의 표면경도를 증가시키기 위해 널리 사용되는 열처리 공정으로, 표면 경화법에는 고주파 표면경화(Induction Surface Hardening) · 화염 표면경화(Flame Surface Hardening) · 레이저 표면경화(Laser Surface Hardening) · 전자빔 표면경화(Electron Beam Surface Hardening) 처리와 같이 재료의 표면만 가열한 후, 급냉 처리하여 마르텐사이트와 같은 경화조직을 표면에 형성시키는 열처리 경화법과, 탄소(Carbon) · 질소(Nitrogen) · 붕소(Boron) 등과 같은 원소를 확산 침투시켜 재료의 표면을 경화시키는 침탄(Carburizing) · 질화(Nitriding) · 침탄질화(Carbonitriding) · 침질탄화(Nitrocarburizing) · 침붕(Boriding) 등의 표면 확산침투법, 그리고 PVD(Physical Vapor Deposition; 물리 증착) · CVD(Chemical Vapor Deposition; 화학 증착) · 이온 플레이팅(Plating) 등과 같이 경질의 원소를 피복하는 코팅법 등이 있다.Surface hardening is a heat treatment process widely used to increase the surface hardness of metal products.The surface hardening method includes induction surface hardening, flame surface hardening, laser surface hardening, A heat treatment hardening method that heats only the surface of a material, such as an Electron Beam Surface Hardening treatment, and then quenches it to form a hardened structure such as martensite, and carbon, nitrogen, boron ( Carburizing, Nitriding, Carbonitriding, Nitrocarburizing, Borideding, etc., surface diffusion infiltration to harden the surface of the material by diffusion and penetration of elements such as boron, and PVD (Physical Vapor Deposition; Physical Vapor Deposition) · CVD (Chemical Vapor Deposition; Chemical Vapor Deposition) · Ion Plating Etc.
대표적인 표면경화법인 침탄(Carburizing)은 표면에 단단한 침탄층을 형성시키기 위해 스테인리스강 내부로 탄소원자를 확산 침투시키는 공정으로, 일반적으로 700℃ 이상에서 침탄을 행한다. 이때 크롬-탄화물이 석출되어 표면경도는 증가 시키지만, 내식성을 향상시키는 크롬원자가 크롬-탄화물을 형성하는데 소비되어 인접지역에 크롬 함량이 낮은 크롬-고갈부(Cr-depleted Zone)를 야기시켜 국부적인 갈바닉 전지(Galvanic Cell)를 형성하기 때문에 내식성에 악영향을 미친다.Carburizing, a typical surface hardening method, is a process in which carbon atoms are diffused and penetrated into stainless steel to form a hard carburized layer on the surface. Carburizing is generally performed at 700 ° C. or higher. At this time, chromium-carbide precipitates to increase the surface hardness, but chromium atoms, which improve corrosion resistance, are consumed to form chromium-carbide, causing a chromium-depleted zone with low chromium content in the adjacent area, thereby causing local galvanic. Because it forms a galvanic cell, it adversely affects the corrosion resistance.
따라서 스테인리스강의 내식성을 유지하면서 경도와 내마모성을 향상시킬 수 있는 공정개발에 많은 관심이 집중되어 왔다.Therefore, much attention has been focused on process development which can improve hardness and wear resistance while maintaining the corrosion resistance of stainless steel.
본 발명은 내식성 손상 없이 표면경도, 피로강도 및 내마모성을 증가시키기 위한 오스테나이트계 스테인리스강 및 Fe-Cr-Ni계 합금의 침탄방법을 제공코자 한다.The present invention is to provide a carburizing method of austenitic stainless steel and Fe-Cr-Ni alloy to increase the surface hardness, fatigue strength and wear resistance without damage to corrosion resistance.
본 발명은 크롬-탄화물 석출이 일어나지 않는 온도에서 표면경화 처리에 의해 내식성을 크게 손상시키지 않으면서 표면경도 및 내마모성을 요하는 제품에 높은 내식성을 부여하는 스테인리스강의 염욕 침탄 열처리 방법을 제공코자 하는 것이다.The present invention is to provide a salt bath carburizing heat treatment method of stainless steel that provides high corrosion resistance to a product requiring surface hardness and wear resistance without significantly impairing the corrosion resistance by surface hardening treatment at a temperature at which chromium-carbide precipitation does not occur.
이에 본 발명에서는 상기한 바와 같은 문제점을 일소할 수 있도록 한 것으로서,In the present invention, to solve the above problems as described above,
본 발명에서 제공하는 고내식성을 갖는 스테인리스강의 염욕 침탄 열처리 방법은 피-침탄제품을 염산 욕에 침지시켜 표면의 부동태 피막을 제거하는 공정과, 시안화나트륨(NaCN)이 주성분인 염에 염화물과 탄산나트륨(Na2CO3)의 탄산염을 가한 염욕에 피-침탄제품을 침지시켜 400℃~550℃에서 10~70시간 동안 시안화나트륨(NaCN)의 분해로 생긴 탄소원자에 의한 침탄을 행하는 공정과, 침탄층 표면에 생성된 산화 스케일 및 스머트(Smut) 형상의 흑색 피막을 질산을 사용하여 화학에칭으로 제거하여 침탄된 제품이 공기와 접촉하여 부동태화되도록 한 것을 특징으로 한다.In the salt bath carburizing heat treatment method of stainless steel having high corrosion resistance provided by the present invention, a process of removing the passivation film on the surface by immersing the carburized product in a hydrochloric acid bath, and salt and sodium carbonate in a salt whose main component is sodium cyanide (NaCN) Immersing the carburized product in a salt bath to which carbonate of Na 2 CO 3 ) is subjected to carburization by carbon atoms resulting from decomposition of sodium cyanide (NaCN) for 10 to 70 hours at 400 ° C. to 550 ° C., and a carburizing layer Oxidation scale and Smut-shaped black film formed on the surface was removed by chemical etching using nitric acid, so that the carburized product was passivated in contact with air.
본 발명의 고내식성을 갖는 스테인리스강의 염욕 침탄 열처리 방법에 의해 관 이음쇠의 후위 페룰, 슬리브, 밸브 시트, 볼트, 너트 및 스크루 등에 사용되는 스테인리스강을 포함하는 Fe-Cr-Ni계 합금의 표면경도 및 내마모성을 향상시킴과 동시에 부식을 방지하는 효과가 있다.Surface hardness of Fe-Cr-Ni-based alloys including stainless steel used in the back ferrules, sleeves, valve seats, bolts, nuts and screws of pipe fittings by the salt bath carburizing heat treatment method of stainless steel having high corrosion resistance of the present invention, and It improves wear resistance and prevents corrosion.
본 발명은 316 · 316L · 304 · 304L 스테인리스강 및 Incoloy 825 · Inconel 600 · Hastelloy C-276 등의 Fe-Cr-Ni계 합금에 적용할 수 있다.The present invention is applicable to Fe-Cr-Ni-based alloys such as 316, 316L, 304, 304L stainless steel, Incoloy 825, Inconel 600, Hastelloy C-276 and the like.
발전설비, 석유화학 플랜트, 해양 플랜트 등의 계기장치 라인의 튜브/파이프를 체결하기 위해 사용되는 관 이음쇠(Fitting)의 핵심부품인 후위 페럴(Back Ferrule), 슬리브(Sleeve)는 튜브를 조여주면서 밀폐를 형성하는 록킹(Locking) 특성이 필요하므로, 상용화된 페럴 및 슬리브는 침탄을 이용한 표면 경화법이 주로 이용되고 있다.Back ferrules and sleeves, which are the core components of the pipe fittings used to fasten the tubes / pipes of the instrument line of power generation facilities, petrochemical plants, and offshore plants, are tightened while the tubes are tightened. Since locking properties are required to form the commercially available ferrules and sleeves, surface hardening using carburizing is mainly used.
도 1은 본 발명에 따른 표면경화 공정을 사용하여 침탄 처리하고자 하는 제품의 한 형태인 관 이음쇠용 후위 페럴(Back Ferrule)의 단면도를 나타낸 것이다.1 is a cross-sectional view of a back ferrule for a pipe fitting, which is a form of a product to be carburized using the surface hardening process according to the present invention.
상기 스테인리스강 후위 페럴의 경우, 튜브 외경을 조이는 노즈(Nose) 부위의 표면경도를 증가시키기 위해 고온 염욕 침탄법으로 노즈 부위만 선택적으로 경화시켰다.In the case of the stainless steel rear ferrule, only the nose portion was selectively cured by high temperature salt bath carburization to increase the surface hardness of the nose portion tightening the tube outer diameter.
즉, 종래의 고온 염욕 침탄공정은 시안화나트륨(NaCN)에 염화바륨(BaCl2), 염화나트륨(NaCl), 염화칼슘(KCl) 등의 염화물과 탄산나트륨(Na2CO3)의 탄산염을 가한 염욕에 제품을 침지시켜 750~900℃의 고온에서 5~8시간 동안 침탄을 행하였다.That is, in the conventional high temperature salt bath carburizing process, a product is added to a salt bath in which carbonates such as barium chloride (BaCl 2 ), sodium chloride (NaCl), calcium chloride (KCl) and carbonate of sodium carbonate (Na 2 CO 3 ) are added to sodium cyanide (NaCN). It was immersed and carburized for 5-8 hours at the high temperature of 750-900 degreeC.
도 2는 고온 염욕 침탄공정으로 제조된 후위 페럴의 침탄층 조직을 나타낸 것으로, 노즈 부위를 따라 약 150㎛ 정도의 침탄층이 형성되었다.Figure 2 shows the carburized layer structure of the rear ferrule manufactured by a high temperature salt bath carburizing process, a carburized layer of about 150㎛ was formed along the nose portion.
이 스테인리스강 후위 페럴을 5% 염화나트륨(NaCl)으로 염수분무시험을 행할 경우, 도 3과 같이 염수분무 시작 10시간 정도에서 부식이 발생하여 48시간 후에는 표면 침탄층이 완전히 부식되어 없어졌다.When the stainless steel rear ferrule was subjected to the salt spray test with 5% sodium chloride (NaCl), as shown in FIG. 3, corrosion occurred at about 10 hours from the start of the salt spray, and after 48 hours, the surface carburized layer completely disappeared.
이는 탄화물 형성을 촉진시키는 700℃ 이상의 고온에서 침탄을 실시함으로 인해 침탄영역에 크롬-탄화물이 석출되어 내식성 유지에 필요한 크롬 원자의 고갈을 초래하여 내식성이 저하되어 부식이 발생한 것이다.This is due to carburization at a high temperature of 700 ° C. or higher, which promotes the formation of carbides, resulting in precipitation of chromium-carbide in the carburized zone, depletion of chromium atoms necessary for maintaining corrosion resistance, and deterioration of corrosion resistance, resulting in corrosion.
따라서 본 발명에서는 스테인리스강의 내식성을 유지하면서 표면경도를 증가시키는 침탄공정을 개발하기 위해, 크롬-탄화물 형성을 촉진하는 온도(700℃) 이하에서 행하는 저온 침탄처리를 시도하였다.Accordingly, in the present invention, in order to develop a carburizing process for increasing the surface hardness while maintaining the corrosion resistance of stainless steel, low temperature carburizing treatment was performed at a temperature (700 ° C.) or lower to promote chromium-carbide formation.
본 발명에 따른 표면경화 침탄공정은 다음과 같다.Surface hardening carburizing process according to the present invention is as follows.
1단계, 피-침탄제품의 표면 부동태 피막 제거 2단계, 탄화물 형성을 촉진하는 온도(700℃) 이하에서 행하는 침탄처리 3단계, 산화 스케일 및 스머트 피막 제거로 침탄공정이 구성된다.The carburization process consists of a first step, a surface passivation film removal step of the object to be carburized, two steps of carburization treatment performed at a temperature (700 ° C.) or lower, and an oxide scale and a smut film removal which are performed at a temperature that promotes carbide formation.
1단계 피-침탄제품을 염산(Hydrogen Chloride) 욕에 침지시켜 표면의 부동 태 피막을 제거한다.Step 1 The carburized product is immersed in a Hydrogen Chloride bath to remove the passivation film from the surface.
2단계, 시안화나트륨(NaCN)이 주성분인 염에 염화바륨(BaCl2), 염화나트륨(NaCl), 염화칼슘(KCl) 등의 염화물과 탄산나트륨(Na2CO3)의 탄산염을 가한 염욕에 피-침탄제품을 침지시켜 탄화물 형성을 촉진하는 온도 이하인 400℃~550℃에서 10~70시간 동안 시안화나트륨(NaCN)의 분해로 생긴 탄소원자에 의한 침탄을 행한다.Step 2 , P-carburized product in salt bath in which salts such as barium chloride (BaCl 2 ), sodium chloride (NaCl), calcium chloride (KCl) and carbonates of sodium carbonate (Na 2 CO 3 ) were added to salts containing sodium cyanide (NaCN) as the main component Carburization by carbon atoms resulting from decomposition of sodium cyanide (NaCN) for 10 to 70 hours at 400 ° C. to 550 ° C., which is below the temperature for promoting carbide formation by dipping, is carried out.
종래의 스테인리스강 후위 페럴은 노즈 부위만 표면경화처리를 하지만, 본 발명에서는 후위 페럴 전 표면을 따라 침탄을 행하였다.The conventional stainless steel rear ferrule is surface hardened only to the nose portion, but in the present invention, carburization is performed along the entire surface of the rear ferrule.
3단계, 침탄처리 후, 침탄층 표면에 생성된 산화 스케일 및 스머트(Smut) 형상의 흑색 피막을 질산으로 화학에칭과 같은 방법으로 제거하면 침탄된 제품이 공기와 접촉하여 부동태화된다.In step 3, after carburizing, the oxide scale and the smut-shaped black film formed on the surface of the carburized layer are removed in the same manner as chemical etching with nitric acid, and the carburized product is contacted with air and passivated.
도 4는 본 발명의 침탄공정으로 처리된 후의 후위 페럴 침탄층 형상을 나타낸 것으로서, 탄소원자의 확산에 의해 내식성을 저하시키는 크롬-탄화물 석출 없이 내식성이 우수한 두께(깊이) 10~50㎛ · 마이크로-비커스 경도 Hv=800~1,200 정도의 침탄층이 형성되어 피-침탄제품의 표면층이 경화된다.Figure 4 shows the shape of the rear ferrule carburizing layer after being treated by the carburizing process of the present invention, the thickness (depth) excellent corrosion resistance without chromium-carbide precipitation deterioration corrosion resistance by the diffusion of carbon atoms 10 ~ 50㎛ micro-Vickers A carburized layer of hardness Hv = 800-1,200 is formed to harden the surface layer of the carburized product.
종래의 고온 염욕 침탄 후위 페럴의 경우, 크롬-탄화물이 석출되어 표면경도는 증가하나 표면부의 크롬 원자가 고갈되면서 내식성이 떨어져 스테인리스강 조직 현출에 주로 사용되는 왕수용액(Aquaregia Etchant)에서는 5초 정도면 표면 침탄층이 에칭(부식)되지만, 본 발명의 표면경화 침탄공정을 적용한 스테인리스강 후 위 페럴은 왕수용액으로 3분 이상 에칭(부식)시켰음에도 불구하고 표면 경화층은 거의 부식되지 않았다.In the case of the conventional ferrule after the high temperature salt bath carburization, the surface hardness increases due to the precipitation of chromium-carbide, but the corrosion resistance decreases due to the depletion of chromium atoms on the surface. Although the carburized layer was etched (corroded), the surface hardened layer was hardly corroded even after the above ferrule was etched (corroded) with aqua regia solution for at least 3 minutes after applying the surface hardening carburizing process of the present invention.
본 발명의 표면경화 침탄공정을 적용한 후위 페럴은 비-침탄영역인 모재가 부식됨에도 불구하고 표면 경화층은 거의 부식되지 않는 것이 특징으로, 내식성이 우수함을 알 수 있다.The rear ferrule applying the surface hardening carburizing process of the present invention is characterized in that the surface hardened layer is hardly corroded even though the base material, which is a non-carburized region, is corroded.
본 발명에 따른 표면경화 침탄처리를 적용한 스테인리스강 제품의 내식성을 염수분무시험(염수 농도 = 5% NaCl · 분무온도 =37℃)으로 평가하면, 도 5와 같이 100시간 이상에서도 녹(부식)이 발생하지 않는다.When the corrosion resistance of the stainless steel product to which the surface hardening carburizing treatment according to the present invention is applied is evaluated by the salt spray test (saline concentration = 5% NaCl · spray temperature = 37 ℃), as shown in Fig. Does not occur.
본 발명의 고내식성을 갖는 스테인리스강의 염욕 침탄 열처리 방법은 각종 산업분야에서 스테인리스강을 사용할 경우 접목시킬 수 있어 관련산업 발전에 일익을 할 수 있는 것이다.Salt bath carburizing heat treatment method of stainless steel having high corrosion resistance of the present invention can be grafted when using stainless steel in various industrial fields can benefit the development of related industries.
도 1은 후위 페럴(Back Ferrule)의 세로방향 단면도1 is a longitudinal cross-sectional view of a back ferrule
도 2는 고온 염욕 침탄 후위 페럴(Back Ferrule)의 침탄 열처리 형상Figure 2 is a carburizing heat treatment shape of the high temperature salt bath carburizing rear ferrule (Back Ferrule)
도 3은 염수분무시험(48시간) 후, 고온 염욕 침탄 스테인리스강 후위 페럴의 부식 양상Figure 3 shows the corrosion behavior of the high temperature salt bath carburized stainless steel rear ferrule after the salt spray test (48 hours)
도 4는 본 발명의 침탄공정에 의해 경화된 후위 페럴(Back Ferrule)의 침탄 열처리 형상Figure 4 is a carburizing heat treatment shape of the back ferrule (Back Ferrule) cured by the carburizing process of the present invention
도 5는 염수분무시험(100시간) 후, 본 발명의 침탄공정이 적용된 스테인리스강 후위 페럴의 부식 양상5 is a corrosion pattern of the stainless steel rear ferrule to which the carburization process of the present invention is applied after the salt spray test (100 hours)
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| KR101166673B1 (en) | 2012-04-20 | 2012-07-24 | 주식회사 비엠티 | Ferrule protect device for part heat treatment |
| WO2015060552A1 (en) * | 2013-10-22 | 2015-04-30 | 디케이락 주식회사 | Partially carburized heat treated stainless ferrule, and manufacturing method therefor |
| WO2015060551A1 (en) * | 2013-10-22 | 2015-04-30 | 디케이락 주식회사 | Partially carburized heat treated stainless ferrule, and manufacturing method therefor |
| KR101515840B1 (en) * | 2013-10-22 | 2015-05-04 | 디케이락 주식회사 | Partially Nitrocarburizing Heat Treated Stainless Steel Ferrule and Manufacturing Method Therefor |
| KR101650318B1 (en) | 2015-03-24 | 2016-08-23 | 금오공과대학교 산학협력단 | Nitriding method of stainless steel |
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