A novel testing machine for a continuous semisolid extending extrusion process (CSEP) has been designed and used to produce AA2017 alloy flat bar. Fine and homogeneous grains of AA2017 slurries with rosette structures were obtained at suitable casting temperatures. During preparation of semisolid AA2017 alloy by the proposed process, rosette grain formation was observed during the application of the large force provided by the rough roll. By controlling casting temperature, AA2017 products were produced with fine surfaces and rectangular transections of 14×25 mm. A casting temperature range of 710–750℃ was suggested. The microstructure of the product is fine and even with striped appearance and is composed mainly of h and a phases. The fracture strength of AA2017 product produced by the semisolid extending extrusion process is improved by 100 MPa, and elongation by 29%.

A novel sloping plate with wavelike surface was used to prepare semisolid alloy. Semisolid billets and slurries have been prepared by cooling or preheating the sloping plate. During preparation of the semisolid alloy by the proposed process, seed crystals derive from burst nucleation and breaking of dendrite and the coaction causes fine spherical microstructure formation. Casting temperature, sloping plate length, degree of cooling sloping angle are the main factors influencing the microstructure. Under current experimental conditions, in order to prepare good quality semisolid billets, proper casting temperature ranges of 660–690℃ for Al–3 wt-%Mg alloy and 660–680℃ for Al–6Si–2Mg (wt-%) alloy are suggested. The reasonable technological conditions for preparing Al–6Si–2Mg (wt-%) slurry are also proposed: the sloping plate preheating temperature is 300℃, and the casting temperature is 680℃. The optimum conditions for preparing semisolid billet of 1Cr–18Ni–9Ti stainless steel were obtained: the sloping plate length is 640 mm, and the casting temperature is 1600℃.

A vibrating wavelike sloping plate process (VWSP) was proposed. Heat and solute transformations, nucleation mechanism and grain growth as well as microstructure evolution were investigated. It is shown that the sloping plate can provide strong undercooling, and a large quantity of heterogonous nuclei appear on the sloping plate surface,wavelike flowand vibration can enable heterogonous nucleus to escape off the plate, which lead to nucleus multiplication. Moreover, wavelike flow and vibration improve solute diffusion coefficient and cause uniform solute and temperature field, which lead to eruptive nucleation. Grain growth has two typical ways, direct globular growth and dendritic growth. Under relative uniform temperature and solute fields, some grains can keep stable growth surface, go on growing with the round surface and finally maintain their globular structure. However, there are always some grains that grow along a certain preferred direction, but under wavelike flow and vibration their dendritic arms break and transform into near spherical structure. During the casting process, microstructural evolution from globular/dendritic structure to globular/equiaxed structure and to globular structure was observed.

利用自制的实验装置对倾斜式剪切冷却技术制备1Cr 18Ni9Ti；不锈钢半固态合金进行了研究·倾斜式剪切冷却技术使熔融1Cr 18Ni9Ti不锈钢合金在剪切冷却作用下形成组织优良的半固态材料；在冷却板的冷却作用与重力的剪切作用下1Cr 18Ni9Ti；不锈钢半固态合金逐渐由树枝晶演化为细小的球形晶；倾角、冷却板长度、冷却板表面性质对合金组织具有重要影响；在倾角为45°，冷却板长度为650mm，冷却板采用紫铜材质的条件下可制备出细小球形的1Cr 18Ni9Ti；不锈钢半固态材料。

Abstract: A self-designed setup of modified sloping cooling/shearing process was made to prepare the semisolid Al-3wt%Mg alloy. A three-dimensional simulation model was established for the analysis of preparing the semisolid Al-3wt%Mg alloy. Through simulation and experiment, it is shown that the sloping angle of the plate greatly affects temperature and velocity distributions, and the temperature and velocity of the alloy at the exit of the sloping plate increase with the increase of the sloping angle. The alloy temperature decreases linearly from the pouring mouth to the exit. The alloy temperature at the exit increases obviously with the increase of pouring temperature. To prepare the semisolid Al-3wt%Mg alloy with good quality, the sloping angle θ=45° is reasonable, and the pouring temperature is suggested to be designed above 650-660℃ but under 700℃.