A novel-type delivery system consisting of a special feeding device and delivery device was developed and applied to a φ600 mm× 1 000 mm twin-roll casting system for producing the steel strip of 2 mm in thickness, and the characteristics of fluid flow and temperature field in the casting pool were investigated by mathematical simulation. The results showed that the melt from the novel-type delivery system was distributed to the casting pool along the width direction smoothly and uniformly. At the casting speed of 80 m/min, the difference of minimum residence time （groin） and actual average residence time （tave） among different ports of the delivery device was less than 0.18 s and 0.26 s respectively, and the average amplitude of level fluctuation was 0.3 mm to 0.6 mm on the free surface of casting pool. In addition, the difference of temperature on the free surface of the pool was below 20 K and the difference across the width direction of roll in different pool depths was less than 13 K, which indicates that the uniformity of temperature distribution was obtained in the casting pool to maintain the casting process and the defect-free steel strip can also be obtained.
C-rowth rate, microstructure and phase composition of scale layer formed during oxidation in 56 % H2O9%O2 N2 and following continuous cooling in ambient air were experimentally investigated by means of optical microscopy, scanning electron microscopy （SEM）, energy-dispersive spectroscopy （EDS） and X-ray diffraction （XRD） for 45, 20CrMnTi and TTS443M steels respectively, to examine the effects of strand surface temperature and steel composition on the scale formation in simulated continudus casting process. The growth rates were found to be ap proximately parabolic and the calculated activation energy of TTS443M steel is much higher than those of the two other steels. For 45 and 20CrMnTi steels, the scale layers were looser and a distinct gap formed at the scale-sub strate interface at higher strand surface temperature. The dominant phases within the scale were iron oxides except for FeO · Cr2O3 phase simuhaneously existing in the oxide scale of 20CrMnTi steel. On the other hand, the scale layer formed on TTS443M steel was compact and tightly attached to the steel surface. At both lower and higher strand surface temperature, iron oxide was main phase in external layer of the scale, while chromia was dominant in inner layer with an appreciable Cr enrichment.
