Fe-Cr-Mo 계 페라이트강의 석출특성에 미치는 질소의 영향

Abstract

In this investigation, effects of nitrogen on the precipitation behavior of Fe -Cr-Mo ferritic steels werestudied. Three alloys having diferent nitrogen content were manufactured by vacuum induction melting in N 2 gasatmosphere. Major precipitates in these steels containing 88 ppm.~682 ppm. nitrogen were M 23C6 and fine MX. Also,FeW2B2 and Cr 2C phases were precipitated in as-tempered condition. The precipitation rate of M 23C6 and MX wereaccelerated by addition of nitrogen. However, formation of the FeW2B2 phase was suppressed with increase innitrogen contents. This is due to the increase of W solubility in the matrix by higher stabilization of austenite withincrease in nitrogen contents. Smal amounts of Laves and CrN phases were additionally precipitated in specimenstempered at 650oC for 3 hours and aged at 700oC for 1000 hours.