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Microstructural Realization of SD400 Rebar by Developing Tempcore Simulation Apparatus

템프코어 냉각모사 장치 개발을 통한 SD400 철근 미세조직 구현

  • 박춘수 (동국제강(주) 중앙기술연구소) ;
  • 이향준 (동국제강(주) 중앙기술연구소) ;
  • 배세욱 (동국제강(주) 중앙기술연구소) ;
  • 김길수 (동국제강(주) 중앙기술연구소)
  • Received : 2015.01.12
  • Accepted : 2015.03.21
  • Published : 2015.05.01

Abstract

The cooling process referred to as Tempcore has been applied to produce a high-strength rebar. Excellent rebar with strength and weldability can be manufactured from mild steel without the addition of alloying elements by using the Tempcore process. However, there are limitations to evaluating the effect of various chemical compositions and cooling conditions within a site facility. In this study, we developed an apparatus to simulate the Tempcore process and obtained microstructures with a hardened surface layer, an intermediate region and a soft inner core. The experimental apparatus has been equipped with a cooler set that is the same as the site facility and consists of a pump line that supplies pressure of 12-13 bar and flow rate of up to $50m^3/h$. In accordance with the simulation result of steel grade SD400 that requires more than 400 MPa of yield strength, both the hardened area ratio and the hardness with respect to each cooling depth were found to agree well with the product.

Keywords

Tempcore;Tempcore Simulation Apparatus;Hardened Layer;Hardened Area Ratio;Hardness;Microstructure;Rebar

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