Study on Microstructure of High PerformanceFire-Resistant and Weathering Construction Steel

摘要

Microstructure of high properties fire-resistant and weathering construction steel with different heat treatment technics had been studied by using OM and TEM. The results showed that microstructure of the hot-rolled 50mm thickness construction steel with the normalizing temperature 910℃～940℃ plus tempering temperature 600℃～700℃ is acicular bainite or ultra low carbon bainite containing a little M/A islands. The fine stable alloy carbonitride distributed along the boundary of low carbon bainite after high temperature tempering is beneficial for the steady of microstructure in high temperature and also improves the fire-resistant performance.