Application and Study on Heat Transfer Model for Continuous 82B Billet Casting
The centerline segregation in the 82B steel billet reduces seriously the final product quality; it is closely related to the unreasonable secondary cooling water system. This paper has established a two-dimensional non-steady-state heat transfer model for the continuous 82B billet casting process, and optimized the existing secondary cooling water scheme, The results show that: the strand surface temperature falling rate is lower than the center temperature falling rate in the original cooling water scheme; it is necessary to add an additional cooling subzone after the fourth subzone for decreasing centerline segregation; the optimal cooling water scheme is that cooling intensity of the fifth subzone is increased by 150% compared with the original fourth subzone.
Effect of complex electromagnetic stirring on inner quality of high carbon steel bloom
To obtain a better internal quality of high carbon steel bloom, complex electromagnetic stirring combined M-EMS with F-EMS was designed. In order to find a proper location for positioning the F-EMS stirrer, the solid shell thickness profile of a continuous casting bloom was computed. It was found that the F-EMS stirrer should be placed 11.39 m below the meniscus. Based on the finding, an industrial plant trial was conducted on the operating bloom casting machine at Baotou Iron and Steel (Group) Corp. The results show that the problem of inner porosity and composition segregation can be solved with the complex electromagnetic stirring technique. The ratio and index of central segregation and porosity can be reduced significantly. Therefore, good casting technique, optimum mould design and final electromagnetic stirring are all important for improving the inner quality of high carbon steel.
Simplified impedance design and control for low-cost high-speed channels
Impedance design is the fundamentals of signal integrity at the very beginning, but controlled impedance is always costly or time-consuming for the high-speed channels. In this paper, many simulations of channel parasitics were taken and calculated that met with the specified impedances and correlated to the measurements very well. Selection of the different substrate stack-up without any layout modification in the BGA package reversed from the failed verification to pass the differential return loss. Adjustment of lead widths and spaces in the limited room of leadframe package improved 6 Ω of differential-mode impedance compared to the conventional leadframe packages. The differential pairs with wider traces routed on the 2-layer PCB are more robust for over-etching effects whose impedance errors are less than 5% without special impedance control. Moreover, those pairs inserted with a thin ground trace achieved 90 Ω differential-mode impedance and 28.2 Ω common-mode impedance simultaneously with 35% less routing area for MHL application and reserved a 10 Ω series resistor for ESD protection. With those diligent designs, the leadframe package and the 2-layer PCB can be still adopting in the consumer electronics for high-speed applications.