• 제목/요약/키워드: Stainless Steels

검색결과 536건 처리시간 0.029초

AISI 316L 클래드강의 맞대기 용접부 입계부식과 예민화 거동에 관한 연구 (The Sensitization and Intergranular Corrosion Behavior of AISI 316L Clad Steel with Butt Welding)

  • 이철구;박재원
    • Journal of Welding and Joining
    • /
    • 제31권2호
    • /
    • pp.49-56
    • /
    • 2013
  • We have investigated traits of clad metals in hot-rolled clad steel plates, sensitization and mechanical properties of STS 316 steel plate and carbon steel(A516). Clad steel plates were butt-weld by SAW+SMAW, and with the time of heat treatment as the variable, heat treatment was conducted at $625^{\circ}C$, for 80, 160, 320, 640, 1280 minutes. As a way to evaluate it, sectioned weldments and external surfaces were investigated to reveal the degree of sensitization by mechanical property, etching and those of EPR test, results were compared with it. In short, the purpose of this study is suggesting some considerations in developing on-site techniques to evaluate the sensitization of stainless steels.

열화 주조 스테인리스강의 환경피로균열 진전 거동 (Environmental Fatigue Crack Propagation Behavior of Aged Cast Stainless Steel)

  • 정일석;이용성;김상재;송택호;조선영
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2004년도 춘계학술대회
    • /
    • pp.78-83
    • /
    • 2004
  • Environmental fatigue crack propagation of CF8M and CF8A steels used in the domestic PWR were investigated on the simulated PWR condition(Temperature: $316^{\circ}C$, Pressure: 15MPa). The test equipment for environmental fatigue(high temperature-high pressure loop, autoclave, load frame, measurement system) were designed. As-received and 60-year aged specimens were used in the test. To compare with environmental fatigue test, another test was performed in the air condition. The fracture surface of specimens were difficult to verify the fracture modes such as striation, intergranular crack and cleavage and so on. As the ferrite content of CF8M is increased, more particles covered fracture surface were peeled.

  • PDF

25Cr-20Ni계 스테인리스강의 크리프 변형중 내부응력과 운동전위밀도의 평가 (Evaluation of Internal Stress and Dislocation Velocity in Creep with 25Cr-20Ni Stainless Steels)

  • 박인덕;안석환;남기우
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2004년도 춘계학술대회
    • /
    • pp.296-301
    • /
    • 2004
  • By the purpose to investigate the change of internal stress and mobile dislocation density in creep, the stress relaxation test is carried out in the condition of each strain. Mobile dislocation density increased until it reached minimum creep rate and after that, it decreased and internal stress didn't have the change approximately until it reached minimum creep rate and after that, it decreased. The stress relaxation rate is fast and approached zero after 1.5 seconds after the beginning of the stress relaxation. And the larger the applied stress is, the larger the internal stress is. By the evaluation of mobility of dislocation, the dislocations glide viscously in STS31OJlTB but it is the dislocations glide viscously which N passes by cutting Cr atom rather than typical viscosity movement after calculating mobility of dislocation.

  • PDF

제설염 환경에서 자동차 배기계용 11% Cr, 17% Cr 페라이트 스테인리스강의 외면부식특성 (Cosmetic Corrosion of 11 % Cr and 17 % Cr Ferritic Stainless Steels for Automotive Exhaust Systems in an Environment containing Deicing Salts)

  • 범원진;박찬진;김영호;유한진
    • 한국표면공학회:학술대회논문집
    • /
    • 한국표면공학회 2008년도 추계학술대회 초록집
    • /
    • pp.31-31
    • /
    • 2008
  • 복합 싸이클 시험 모니터링을 통해 NaCl, $CaCl_2$ 제설염 환경에서 11 % Cr, 17 % Cr 페라이트 스테인리스강의 외면부식특성을 조사하고자 하였다. 용액 내 NaCl 및 $CaCl_2$의 농도가 증가함에 따라 용액의 pH가 떨어졌으며, $CaCl_2$의 농도증가에 따른 산성화도가 NaCl에 비해 크게 나타났다. 염수분무-건조-습윤 과정의 반복으로 구성되어 있는 복합싸이클 시험 중 소재의 표면상태 변화를 모니터링 한 결과, 건조 과정 중에 공식이 시작되며, NaCl 환경의 경우엔 습윤과정 중에 $CaCl_2$ 환경의 경우엔 건조 중에 공식성장이 주로 이루어지는 것으로 확인되었다.

  • PDF

Various Master Sintering Curve Concepts and its Applications

  • Park, Seong-Jin;Blaine, Deborah C.;German, Randall M.
    • 한국분말야금학회:학술대회논문집
    • /
    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
    • /
    • pp.66-67
    • /
    • 2006
  • The master sintering curve (MSC) is derived from densification data over a range of heating rates and temperatures. To improve the accuracy, several modifications were proposed: multi-phase MSC for solid state sintering with phase changes, MSC for liquid phase sintering, and MSC with consideration of grain growth. The developed MSC models were applied to several material systems such as molybdenum, stainless steels, and tungsten heavy alloys (WHA), in order to evaluate the effect of compaction pressure, phase change, grain growth, and composition on densification, to classify regions having different sintering mechanism, and to help engineer design, optimize, and monitor sintering cycles.

  • PDF

Co-sintering of M2/316L Layers for Fabrication of Graded Composite Structures

  • Firouzdor, V.;Simchi, A.;Kokabi, A.H.
    • 한국분말야금학회:학술대회논문집
    • /
    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
    • /
    • pp.696-697
    • /
    • 2006
  • This paper presents the densification and microstructure evolution of bilayer components made from 316L stainless steel and M2 High speed steel during co-sintering process. The sintering was carried out at temperatures ranging from $1230-1320^{\circ}C$ in a reducing atmosphere. The addition of boron to 316L was examined in order to increase the densification rate and improve the sintering compatibility between the two layers. It was shown that the mismatch strain bettwen the two layers induces biaxial stresses during sintering, influencing the densification rate. The effect of boron addition was also found to be positive as it improves the bonding between the two layers.

  • PDF

304L 스테인리스강의 저온 플라즈마질탄화 및 2-step 플라즈마 프로세스 (Low temperature plasma nitricarburizing and 2-step plasma processes of 304L austenitic stainless steels)

  • 이인섭
    • 한국표면공학회:학술대회논문집
    • /
    • 한국표면공학회 2007년도 추계학술대회 논문집
    • /
    • pp.65-68
    • /
    • 2007
  • 저온 플라즈마 기술을 이용하면 오스테나이트계 스테인리스강의 내식성과 표면경도를 동시에 증가 시킬 수 있다. 여러 가지 처리방법 중 질탄화와 2-step 공정으로 처리한 AISI304L강의 표면을 분석하였다. 처리한 모든 시편의 표면은 expanded austenite(${\gamma}_N$)이 형성되었고, 표면 경도도 모재보다 약 4배 이상 증가 하였다. 저온플라즈마 질탄화 공정의 경우 경화층의 두께가 최대 15 ${\mu}m$밖에 형성되지 않았지만 2-step공정의 경우 질탄화 공정보다 짧은 시간으로 약 2배의 경화층을 얻을 수 있었다. 두 가지 공정 모두 온도와 시간이 증가할수록 경화층의 두께가 두꺼워졌지만, 과도하게 높은 온도와 긴 공정시간은 석출물을 형성 시켰다. 석출물이 형성되지 않은 시편의 경우 내식성이 증가하였다.

  • PDF

플라즈마 질화 온도에 따른 스테인레스 강의 내식성 연구 (The study of corrosion resistance property of stainless steels with Plasma Nitriding Temperature)

  • 여국현;박용진;김성철;김상권;이재훈
    • 한국표면공학회:학술대회논문집
    • /
    • 한국표면공학회 2012년도 춘계학술발표회 논문집
    • /
    • pp.309-310
    • /
    • 2012
  • 스테인레스강의 내식성을 향상시키기 위한 고농도 침입형 질화층(S-phase)처리를 하는 논문들이 발표되고 있지만 테스트 시편이 아닌 실제 제품이나 가공품등의 질화 처리 하였을 경우 내식성향상이 아닌 저하되는 것을 볼 수 있다. 스테인레스강의 제품화 과정에서 압연 및 기계가공에서 발생되는 각종 문제, 가공경화로 인한 현상 및 질화 처리후 표면개질의 석출상이나 입계로부터 시작되는 크랙이 내식성을 저감시키는 경향을 살펴보았다. 이러한 경향은 봉재나 두꺼운 소재보다는 가공소재인 판재나 형상이 있는 제품에 더 심하게 나타나는 것을 보여준다. 소재의 관리와 질화 온도 및 여러가지 변수에 의해 최적화 되어 S-phase 질화층을 형성해야 내식특성을 유지 할 수 있다.

  • PDF

FeCrMnN 계 스테인리스강의 일반부식 및 공식부식 거동에 미치는 고용 탄소의 영향 (Effects of Alloyed Carbon on the General Corrosion and the Pitting Corrosion Behavior of FeCrMnN Stainless Steels)

  • 하헌영;이태호;김성준
    • 대한금속재료학회지
    • /
    • 제49권10호
    • /
    • pp.780-789
    • /
    • 2011
  • The effects of alloyed carbon on the pitting corrosion, the general corrosion, and the passivity behavior of Fe18Cr10Mn0.4NxC (x=0~0.38 wt%) alloys were investigated by various electrochemical methods and XPS analysis. The alloyed carbon increased the general corrosion resistance of the FeCrMnN matrix. Carbon enhanced the corrosion potential, reduced the metal dissolution rate, and accelerated the hydrogen evolution reaction rate in various acidic solutions. In addition, carbon promoted the pitting corrosion resistance of the matrix in a chloride solution. The alloyed carbon in the matrix increased the chromium content in the passive film, and thus the passive film became more protective.

스테인레스강의 스케일 형성에 관한 연구 (A study on the formation of oxide scale on the stainless steels at high temperature)

  • 손일령;김길무
    • 한국표면공학회지
    • /
    • 제27권3호
    • /
    • pp.123-133
    • /
    • 1994
  • Oxidation behavior of STS 304 and 430, produced by POSCO, Korea, was studied in order to study the surface defects formed during manufacturing processes. Oxidation experiments were carried out in a preheat-ed furnace at 850~$1, 250^{\circ}C$ in air and in a simulated coke oven gas(COG) atmosphere. The reaction products were examined by XRD, SEM and EDX on their surfaces and cross sections. Protective $Cr_2O_3$-primary oxide film was formed initially, but at critical point this film was broken and a duplex scale consisting of $Fe_2O_3$- and Fe$Cr_2O_4$- was formed. It was more severely attacked in a simulated COG atmosphere than in air, and STS 304 was superior to STS 430 in oxidation resistance.

  • PDF