서지주요정보
주조용 텅스텐 함유 이상 스테인레스강의 개발 및 주물의 응고거동 및 기계적 성질에 미치는 질소의 영향 = The development of cast duplex stainless steel containing W and the effect of nitrogen on the solidification and mechanical property of the casting
서명 / 저자 주조용 텅스텐 함유 이상 스테인레스강의 개발 및 주물의 응고거동 및 기계적 성질에 미치는 질소의 영향 = The development of cast duplex stainless steel containing W and the effect of nitrogen on the solidification and mechanical property of the casting / 박영환.
발행사항 [대전 : 한국과학기술원, 2002].
Online Access 원문보기 원문인쇄

소장정보

등록번호

8013357

소장위치/청구기호

학술문화관(문화관) 보존서고

DMS 02007

휴대폰 전송

도서상태

이용가능

대출가능

반납예정일

리뷰정보

초록정보

25Cr-7Ni-1.5Mo-3W-xSi duplex stainless steel(DSS) alloys were cast in shell mold with different silicon contents from 0.47 to 1.2 wt%. The effect of Si content on the average fluidity length of the melt and the tensile property of the casting were investigated. The alloys having 0.7∼1.1 wt% Si showed good fluidity, and the strength of the casting slightly increased with increase of Si content. 25Cr-7Ni-1.5Mo-3W-xN duplex stainless steel(DSS) alloys were cast in shell mold with different nitrogen contents from 0.14 to 0.37 wt%. These DSS castings were isothermally heat treated in the temperature range of 950~1350℃ for 2 hours and then quenched in water. The effects of nitrogen contents and solution treatment temperature on the microstructure and mechanical properties of DSS casting were investigated and related to the change of the volume fraction of ferrite. The volume fraction of ferrite was significantly decreased and the solidification mode changed from ferrite single phase solidification mode to ferrite - austenite one by the increased nitrogen content. The increase of solution treatment temperature increased the volume fraction of ferrite and the size of austenite phase in ferrite matrix. The increase of the volume fraction of ferrite decreased the tensile strength and the elongation and increased the yield strength of DSS casting lineally. The effect of misch metal(MM) on the microstructure of a duplex stainless steel(DSS) was investigated. Fe-25Cr-7Ni-3Mo-0.25N DSS ingot without MM, as a basic material was prepared in a 30-kW air induction furnace. Remelting and addition of MM were carried out in a vacuum induction furnace. Various amounts, from 0.022 to 0.078 wt% of MM were added to the 900g DSS melt in an Ar gas environment. The temperature of molten steel was kept at 1650℃ and was measured by two-color pyrometer. DSS samples with different MM contents were cast in a steel mold and 10mm thick castings were obtained. Each casting was solution-treated at 1050℃. The microstructures and the mechanical properties of hot-rolled specimens were compared. The alloying experiment of nitrogen gas into the melt of DSS Fe-25Cr-7Ni-3Mo-2W by blowing on the top surface or bubbling through the melt was analyzed in terms of reaction rate constant and total nitrogen content. The rate constant k between nitrogen gas and the DSS melt is about $2.37 × 10^{-6}$ $mol cm^{-2} s^{-1} atm^{-1}$. The nitrogen solubility in the DSS melt is estimated to be 0.351 wt% at 1600℃. The nitrogen reaction rate of the DSS melt with nitrogen gas at 1600℃ can be expressed as: \\ \begin{equation} \frac{d \left[ wt % N \right]}{dt} = 6.64 × 10^{-3} \frac{A}{W} \left( p_{N_2} –6.58 left[ wt % N \right]^2 10^{0.26 left[ wt % N \right]} \right) \end{equation} The effects of casting thickness, nitrogen contents, cooling rate and Mn contents on the formation of nitrogen gas defects during solidification of 25Cr-7Ni-1.5Mo-3W Duplex Stainless Steels were quantitatively investigated. In case of a sand-mold, the formation of nitrogen gas defects wasn’t affected by the thickness of castings which ranged from 13 to 52mm and the critical initial nitrogen content for the formation of gas defects was 0.30 wt % N. In case of the molds made of a Stainless Steel(STS) and water-cooled Cu, the critical initial nitrogen contents did not change very much compared to the sand mold. The amount of nitrogen gas defects increased with initial nitrogen contents of castings. The segregation of nitrogen and alloying elements were calculated with Thermo-Calc software. The calculated data and the experimental results were used for the estimation of the critical nitrogen partial pressure at the onset of gas pore formation. The effect of Mn content on the formation of gas pores was also investigated.

서지기타정보

서지기타정보
청구기호 {DMS 02007
형태사항 x, 130 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Young-Hwan Park
지도교수의 한글표기 : 이진형
지도교수의 영문표기 : Zin-Hyoung Lee
수록잡지명 : "The effect of nitrogen and heat treatment on the microstructure and tensile properties of 25Cr-7Ni-1.5Mo-3W-xN duplex stainless steel castings". Materials science and engineering A, A297, pp. 78-84 (2001)
학위논문 학위논문(박사) - 한국과학기술원 : 재료공학과,
서지주기 참고문헌 수록
주제 이상 스테인레스강
주물
질소
기포 결함
Duplex stainless steel
Casting
Nitrogen
Gas pore
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