Effects of process parameters on surface quality, composition segregation, microstructure and properties of QSn6. 5-0. 1 alloy slabs fabricated by HCCM horizontal continuous casting

Columnar-grained QSn6. 5-0. 1 alloy slabs with a width of 70 mm and thickness of 10 mm were fabricated by heating-cooling combined mold (HCCM) horizontal continuous casting. The effects of process parameters on solidification microstructure, surface quality, composition segregation and mechanical properties were studied. The results showed that the slabs with good surface quality, excellent mechanical properties and no obvious segregation could be prepared at the melt casting temperature of 1250 °C, the heating-mold temperature of 1150-1200 °C, the cooling water flow rate of 600 L/h and the casting speed of 20-80 mm/min. The slabs had the yield strength of 124-155 MPa, the elongation rate of 46.6%-56.3% and the surface roughness of 0.22-0.55 μm, which enabled them to be directly processed without subsequent milling surface. The ratio of Sn content in the surface to that in the core was 0.83-1.10, with an average value close to 1.0, and not obviously influenced by process parameters. When the casting speed increased from 20 to 80 mm/min, the grain size changed little if the other process parameters were the same. When the heating-mold temperature increased from 1150 to 1200 °C, the grain size was obviously refined and became more uniform if the casting speed was the same. Within the range of the casting speed at which the columnar grain structure could be obtained, the columnar grain size was mainly influenced by the heating-mold temperature.