Effect of Ni on the High Strength Characteristic of 9Cr Ferritic Heat Resistant Steel Applied to the Power Plants

발전플렌트용 9Cr 페라이트 내열강의 고온강도 특성에 미치는 Ni의 영향

This present study was investigated effect of Ni contents on the high temperature strength characteristic in 9Cr ferritic heat-resistant steel added 1.7%W in place of Mo in order to restraint laves phase formation. Precipitation amount of carbide, number of particle per unit area and particle size of carbide were decreased with increase of Ni content. In the steels, carbides of $M_{23}C_6$ type was mainly precipitated, but laves phases could not precipitated. Tensile and yield strength, creep strength and creep rupture time was decreased, but elongation were increased due to decreasing of particle number per unite area and carbide amount precipitated with increase of Ni content.