반복적인 침탄과 탈탄 반응을 통한 α-iron 결정립 미세화

Abstract

The refinement technique using repeated carburizing and decarburizing and the pinning effect of sulfur and Fe3C against grain growth are researched. α → γ phase transformation refines the grain size, on the other hand, the opposite transformation does not. Repeated α - γ phase transformation makes grain size get smaller. Without pinning elements, grain refinement has limitation. Sulfur and Fe3C have grain boundary pinning effect. Sulfur does not have enough pinning effect on grains with the size of less than 30㎛. Fe3C supplies a lot of nucleation site for ferrite nuclei and retards ferrite grain growth up to 10㎛. Manganese stabilizes Fe3C at 800℃ so that Fe3C can help grain refinement by repeated phase transformation at 800℃.