• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.225-227
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• 2004

Recrystallization textures of ferritic stainless steel sheets of STS 430 were varied by means of different cold rolling procedures. The conventional normal rolling led to the evolution of strong through-thickness texture gradients in the final recrystallization texture, while the cross-rolling led to a decrease in texture gradients. Micro-texture observation by EBSD revealed that the formation of band-like orientation colonies formed close to the center layer was responsible for ridging. Modification of the recrystallization texture and microstructure by cross-rolling destroyed band-like orientation colonies and consequently reduced the ridging height.

• Journal of Welding and Joining
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• 제32권1호
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• pp.66-70
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• 2014

In Ti active brazing of YSZ to STS 430 using Ag-Cu Filler Metal, the effect of Ti contents on the shear bonding strength were investigated together with the effect of brazing temperature and holding time. The addition of Ti in Ag-Cu Filler Metal increased the bonding strength up to 4.68% Ti, followed by the decrease with further addition. This seems to be caused by formation of TixOy at the reaction layer. Brazing temperature was optimized at $960^{\circ}C$ among a given temperature ranges. The addion of Sn to Ag-Cu filler metal brought the decrease of its melting temperature its melting temperature without a significant decrease of bonging strength.

• 한국수소및신에너지학회논문집
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• 제20권6호
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• pp.455-463
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• 2009

코발트 보호막 코팅이 적용된 페라이트계 스테인리스 스틸인 STS 430과 STS 444 소재에 대해 고체산화물 연료전지용 금속연결재로서의 고온 산화 특성에 대해 살펴보았다. 코발트 코팅층은 $800^{\circ}C$ 고온 산화 후 코발트 산화물 및 $Co_2CrO_4$, $CoCr_2O_4$, $CoCrFeO_4$ 등과 같은 코발트가 함유된 스피넬 상을 형성하였다. 또한 페라이트계 스테인리스 스틸과 코발트 코팅의 계면에서 크롬과 철이 함유된 치밀한 산화층을 형성하여 금속연결재 표면의 스케일 성장속도를 감소시키고 금속연결재 내에 함유된 크롬의 외부 확산을 효과적으로 억제하였다. 한편 STS 430은 고온 산화 후 표면에 형성된 스케일 하부에 $SiO_2$와 같은 내부 산화물이 형성된 반면 STS 444는 표면 스케일 이외에 다른 내부 산화물은 확인되지 않았으며 고온에서의 면저항 측정 결과, 코발트가 코팅된 STS 444의 전기 전도성이 STS 430 보다 우수한 것으로 나타났다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.89-93
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• 2001

This study was carried out to investigate the warm deep drawability of square cups of clad sheet metals, by changing temperatures of die and blankholder and blank materials. Two kinds of clad sheet metals, STS304-A1050-STS304 and STS304-A1050-STS430 were chosen for experiments. The relative drawing depth of STS304-A1050-STS304 clad sheet was increased up to 4.4 at $150^{\circ}C$ that was $29\%$ higher than at room temperature, whereas STS304-A1050-STS430 material was improved to 3.65 at $120^{\circ}C$ which was $16\%$ better than at room temperature. In addition, comparison of wall thickness and hardness of a warm drawn cup with those of room temperature showed more even distributions. Therefore, warm forming technique was confirmed to ive better results in deep drawing of stainless clad sheet metal.

• 소성∙가공
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• 제10권3호
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• pp.253-260
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• 2001

This study was performed to investigate the optimized warm forming conditions which gave the maximum drawing depth in square cup drawing of clad sheet metals, by changing the temperatures of die and blankholder and also shapes and materials of blanks. Two kinds of clad sheet metals, STS304-A1050-STS304 and STS304-A1050-STS430 were selected for experiments. The relative drawing depth of STS304-A1050-STS304 clad sheet was increased up to 4.4 at $150^{\circ}C$ that was 29% higher than at room temperature, whereas STS304-A1050-STS430 material was improved to 3.9 at $120^{\circ}C$ which was 15% better than at room temperature. In addition, comparison of wall thickness and hardness of a warm drawn cup with those of room temperature showed more even distributions. No separation between each laminated material after drawing occurred through inspection by microscope as well as application of penetrant test and bond strength test. Therefore, warm forming technique was confirmed to give better results in deep drawing of stainless clad sheet metal.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.137.2-137.2
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• 2010

본 연구는 스테인리스 스틸(STS)을 직접메탄올 연료전지(DMFC)용 바이폴라 플레이트에 적용하기 위한 것이다. 약산성의 연료전지 환경에서 부식저항성을 향상시키고자 오스테나이트계 STS 316L과 페라이트계 STS 430에 UBM(unbalanced magnetron) DC sputter로 CrN 코팅막을 제작하였다. CrN이 코팅된 스테인리스 스틸은 부식특성, 접촉 저항 및 접촉각 등을 측정하여 무 코팅의 스테인리스 스틸과 특성을 비교하였다. 그리고 이들 재료의 연료전지(DMFC) 적용 가능성을 알아보기 위하여 단위전지로 제작하여 연료전지 성능 등을 측정하고 평가하였다. 무 코팅 스테인리스 스틸(STS 316L, STS 430)과 CrN 코팅 스테인리스 스틸의 부식저항 특성은 동전위와 정전위 실험으로 조사하였다. 동전위 부식 실험은 -0.4~1.0 V로 0.001 M의 황산용액 또는 메탄올을 첨가하여 질소 또는 공기의 환경에서 실험을 실시하였으며, 정전위 부식 실험은 0.4 V 또는 0.6 V에서 진행하였다. 연료전지의 단전지 측정은 실제 DMFC의 운전조건에서 실시하였다. 부식실험과 단전지 실험 전/후 메탈 바이폴라 플레이트의 조직 변화는 SEM을 통해 관찰하였고, 부식산화물의 화학적 조성과 메탈 바이폴라의 표면은 EDS를 이용하여 측정하였다.

• 열처리공학회지
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• 제27권1호
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• pp.15-22
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• 2014

This study is to investigate the phase changes and cold workability after isothermal transformation at $780^{\circ}C$ by using the high temperature gas nitrided (HTGN) STS 430 ferritic stainless steel specimens. The phase diagram of STS 430 steel obtained by calculation showed that the phase appeared at $1100^{\circ}C$ showed as ${\alpha}+{\gamma}{\rightarrow}{\gamma}{\rightarrow}{\gamma}+Cr_2N{\rightarrow}{\gamma}+Cr_2N+CrN$ with increasing nitrogen concentration. Also, the transformation of ${\gamma}{\rightarrow}Cr_2N$ during heat treatment isothermally at $780^{\circ}C$, nitrogen pearlite with lamellar type was fully formed at the nitrogen permated surface layer for 10 hrs. However, this transformation was not completed for 1 hr, resulting nitrogen pearlite plus martensite. The cold rolled specimen of isothermally transformed at $780^{\circ}C$ for 10 hrs after high temperature gas nitriding decreased the layer thickness of nitrogen pearlite inducing the deformation of hard $Cr_2N$ phase. the dissolution rate of $Cr_2N$ phase increased rapidly with increasing cold rolling ratio. Specimens with the microstructure of nitrogen pearlite (isothermally transformed at $780^{\circ}C$ for 10 hrs) were possible to cold rolling without crack formation. However, the mixed structures of nitrogen pearlite + martensite (isothermally transformed at $780^{\circ}C$ for 1 hr) were impossible to cold deformation without cracking.

• 한국표면공학회지
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• 제53권2호
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• pp.72-79
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• 2020

Two Fe-Cr steels of T22 steel and STS430 steel were corroded at 650 and 750℃ for 100hr in sewage sludge-(0.3% SO₂-6% O₂-10% H₂O-balance CO₂) mixed gas environment. T22 steel corroded faster than STS430, indicating that the Cr content significantly influence the corrosion rates. T22 formed thick and non-protective Fe₂O₃ as the major oxide and Fe₃O₄ as the minor one. With an increase in corrosion temperature, their corrosion rates increased, being accompanied with formation of pores and cracks in the thickened oxide scales that were non-adherent. STS430 steel formed Fe₂O₃, Fe₃O₄ as the outer scale and (Fe, Cr)-O as the inner layer by which its corrosion rate is greatly reduced. Both the T22 and STS430 steel samples formed multi-layered scales by outward diffusion of Fe ions and inward diffusion of oxygen and sulfur ions at high-temperature more than 650℃.

• 한국표면공학회지
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• 제27권3호
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• pp.123-133
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• 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.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 금형가공 심포지엄
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• pp.8-18
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• 1998

The effect of press warm forming in cylindrical deep drawing of stainless-aluminum clad sheet metals are examined . The temperature of die and blank holder is varied from room temperature to 20$0^{\circ}C$, while the punch is kept cooled during test to increase the fracture strength of workpiece on the punch corner area. Test materials chosen for experiments are STS304-Al050-STS304, STS304-A1050-STS430-, STS304 and Al050 metals and teflon film as a lubricant is used on both sides of a workpiece. The limit drawing ration as well as quality of drawn cups (distribution of thickness and hardness)are investigated and discussed.