Formation Mechanism of Surface Crack and Its Control on Continuously Cast Slabs of Nb-containing Austenitic Stainless Steel

Nb 첨가 오스테나이트계 스테인레스강의 연속주조시 표면크랙 형성기구 및 제어

  • Shim, Sang-Dae (Stainless Steel Research Group, POSCO Technical Research Lab.) ;
  • Kim, Sun-Koo (Stainless Steel Research Group, POSCO Technical Research Lab.)
  • 심상대 (POSCO 기술연구소 스테인레스 연구그룹) ;
  • 김선구 (POSCO 기술연구소 스테인레스 연구그룹)
  • Published : 2001.10.20

Abstract

Nb-containing austenitic stainless steel is widely used as exhaust frame and diffuser assembly in power plant. However, this steel is known to be difficult to produce by the continuous casting process due to the surface cracks. Therefore, the continuous casting technology was developed for the prevention of the surface cracks on CC slabs. Precipitates and the analysis of heat trasfer in a slab were investigated in order to find out the formation mechanism of surface cracks on cc slabs It was found that surface cracks are occurred due to the NbC precipitates, which are formed along the grain boundaries around $800^{\circ}C$. The secondary cooling pattern has been developed to produce the defect free CC slabs of Nb-containing austenitic stainless steel.

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References

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