Make the best use of the rare earth elements added in steel through improving the metallurgical technology

摘要

With the past experiences and the current market demands, WISCO has further strengthened its production of RE steel through continuously improving on the metallurgical technologies, decreasing oxygen content in the molten steel prior to the RE treatment and upgrading the RE feeder. BY the end of 1996, the accumulative total output of the continuous easting RE steel reached up to 1.4 million tons, among which there are 7 series of products covering nearly 50 grades including steels for high toughness petroleum steel pipe, pressure vessel, welded structure, containers, rail tunk car, automobile frame and low-carbon steel structure. The present paper introduced mainly the application of RE to production of 15MnHP gas bottle steel. The practices have shown that the RE elements are well-distributed in the slab; the yield of the RE elements increases with the increase of acid-souble-aluminium in the steel and wire feeding velocity; configuration of the non-metal inclusions are modifed in varying degrees representing the metamorphism of RE elements is fully functioned; the homogeneity and the low temperature brittleness on finished plates have been remarkably improved, the crystal grain size in the finished plate is nomorly settled at class 12. The experiment results and theoretical analysis have shown that after RE feeding into 15MnHP steel which has already been world advanced product, the comprehensive performances of the finished products are obviously further improved, especially in the aspects of surface quality and drawing performance, and the goal of RE treating for steel has been perfectly fulfiled.