Effect of Vanadium on the Microstructure and Elevated Temperature Properties of Fire Resistant Steels

Abstract

The combined addition of molybdenum and niobium is usually applied in fire-resistant steels with appropriate controlled rolling and controlled cooling. In order to develop new alloying strategy based on the advantage of vanadium resource at Panzhihua Iron& steel (group) Co., research on the Vanadium-containing fire-resistant weathering steels are conducted in this paper. Methods such as electron microscope, phase analyzing, tensile test, three dimension atom probe and so on were used to investigate the effect of vanadium on microstructure and tensile properties at both room temperature and high temperature up to 600°C for different processes. The relationship between the microstructure and properties was analyzed. It has been found that the amount of vanadium precipitates would be raised as vanadium content rose. Adding vanadium into the steel was effective to increase the room temperature and elevated temperature yield strength, especially increased the content of nitrogen. Vanadium mainly exists in the pro-eutectoid ferrite of the test steel, the “hidden” vanadium will precipitate from base microstructure when the temperature elevated to 600°C, simultaneously improve the elevated temperature properties. The alloying strategy of fire-resistant weathering steels at Pangang Steel is ascertained through the experimental work. The study offers the essential technical support for the further development of products.