Nb첨가 저합금강의 오스테나이트/페라이트 상변태를 이용한 석출물 정량분석

초록

In Nb, V and Ti added steel, carbo-nitrides are formed due to their strong interaction with C and N. The formation of carbo-nitrides has an important role to control the microstructure as well as mechanical properties by grain size refinementand precipitation hardening, However, the quantitative analysis of distribution of precipitates and the effect of precipitates on the phase transformation and mechanical properties are still far form satisfactory. In this study, the quantative analysis of precipitates in austenite was investigated using the fact that the formation of precipitates in Nb, V, and Ti added steels accelerates austenite/ferrite transformation. The formation of precipitates were controlled by adjusting holding temperature and time in austenite. Volume fractions transformed were measureed by dilatometer during slow cooling.