Aluminum and Vanadium Competition for Nitrogen in Thin Slab Processing

摘要

Compact strip production (CSP) is a newer casting process that has proved to be an economic alternative to conventional steel processing. Figure 1 is a schematic diagram of the CSP process. In this process, slabs are typically only 50 mm thick - instead of the traditional 200-250 mm thick - and the solidification rate is faster for CSP material. Another predominant difference is that most CSP material does not undergo the austenite-ferrite-austenite phase changes that conventionally produced steel does. Directly after casting, the slab goes into a tunnel furnace instead of cooling to room temperature prior to reheating. The soaking temperature of the tunnel furnace is lower for CSP material than conventionally produced steel, typically around 1,150℃ (2,102°F) for about 20 minutes instead of 1,250-1,400℃ (2,282-2,552°F) for conventional steel. Slab surface temperature at the base of the caster is about 1,010℃ (1,850°F), and after equalizing the surface temperature is 1,065℃ (1,949°F). The as-cast grain size is smaller in CSP material due to the faster solidification rate, but the austenite-ferrite-austenite phase changes refine the microstructure in conventional material prior to soaking.