Effects of Ultrasonic Treatment during the Solidification Process on the Structure Formation of Low Carbon Steel
This paper studied effects of ultrasonic treatment during the solidification process on structure formation of low carbon steel. Results showed that with ultrasonic treatment grains were refined and the steel ingot avoided the cast widmanstatten structure. When ultrasonic treatment was employed, pearlite was broken and the average length of pearlite was decreased from 550 mm to 140 mm. The corresponding aspect ratio was reduced from 12 to 1. At high magnification the treated pearlite was cloud-like, rather than plate-like, as normal. Ultrasonic treatment also can remove the gas from low carbon steel. These phenomena of low carbon steel generated by ultrasonic treatment were explained. [doi:10.2320/matertrans.M2011091]
Study of ultrasonic melt treatment on the quality of horizontal continuously cast Al-1%Si alloy.
The fluctuation of the melt temperature in a tundish was measured during casting and experiments were conducted to investigate the effects of ultrasonic melt treatment on the surface quality and solidification structures of Al-1%Si ingots. The results show that the uniformity of melt temperature was enhanced with the application of ultrasonic melt treatment. When the ultrasonic power is 1,000W, the surface quality was evidently improved and grains of cast ingots were refined. Moreover, EPMA analysis was adopted to study the relationship between the ultrasonic power and boundary segregation of Si element. The result shows that boundary segregation is suppressed with the increase of ultrasonic power and the phenomenon was theoretically interpreted.
Heat Transfer Characteristic for a New Plate Metal Hydride Reactor
The property of major metal hydride reactors in the world was analyzed and a new plate metal hydride reactor was designed.An experimental facility to test the metal hydride reactor was also designed correspondingly.The effective thermal conductivity of the plate metal hydride reactor was measured by varying the initial metal hydride packing fraction,the kind of filled gas and the pressure of the filled gas,cycle numbers.The test results show that the effective thermal conductivity of the reactor,has exceeded(7.5) W/(m·K) before activation,which is increased greatly.After alloy activation,the effective thermal conductivity of the reactor has a linear change trend with the hydrogen pressure during the interval 0.1~3.5 MPa.The effective thermal conductivity of the reactor just only decreases quickly at the beginning,but becomes stable after several cycles.