Process parameter optimizing and studies on microstructure and properties of AZ31 alloy prepared by semisolid rolling process

Abstract

A novel continuous semisolid rolling process for producing AZ31 alloy strip was developed. The process parameters were optimized, and microstructure and properties of AZ31 alloy prepared by the process were studied. The results reveal that primary grains of the strip become coarse, and the grain structure transforms from round shape to dendrite with the increment of casting temperature gradually. Eutectic phase fraction and primary grain size increase with the increment of roll speed. The primary grain size decreases firstly and then increases with the increment of the vibration frequency correspondingly. When the casting temperature is from 650 • C to 690 • C, the roll speed is 0.069 m·s −1 , and the vibration frequency is about 80 Hz, AZ31 alloy strip with a cross section size of 4 mm×160 mm was prepared by the proposed process. The ultimate tensile strength and elongation are improved 1% and 57%, respectively.

Microstructure evolution during novel rheorolling process for producing A356 alloy strip

“…The Prandtl number of liquid metal is about 0·004–0·029, which implies that the thickness of the velocity boundary layer is much smaller than that of the temperature boundary, This implies that the distribution of the velocity and temperature layer in most part of the melt is homogeneous, except that a velocity gradient exists in a tiny layer close to the plate surface 17. According to the convection heat transfer formula, it can be calculated and measured that the cooling rate of the melt on the plate surface can reach 1000 K s −1 , which is much larger than the conventional casting process 17,18. Then, the homogeneous undercooling can form easily in most of the melt.…”

Phase Transformation and Carbide Precipitation of Functional Gradient Semi-solid 9Cr18 Steel

“…At semi-solid temperature range, non-dendritic microstructure of solid spheroids and liquid film demonstrates thixotropic flow behavior, which will help the filling of dies [3]. Researchers have proposed several methods to obtain the non-dendritic microstructure, for example mechanical stirring, magneto hydrodynamic stirring and SIMA (straininduced melt activation) [4]. SSF can be divided into rheoforming and thixoforming due to the difference of concrete procedures [5].…”

Influence of Processing Parameters on Microstructural Evolution and Tensile Properties for 7075 Al Alloy Prepared by an ECAP-Based SIMA Process

“…Semisolid processing (SSP), as a near net-shape manufacturing technology, is of high economic and technical interest. SSP combines the advantages of casting and forging [4] and has been successfully performed on nonferrous alloys [5][6][7][8], steels [9,10] and composites [11]. The preparation of semisolid slurry with a microstructure consisting of equiaxed grains and continuous liquid films at grain boundaries is essential for subsequent processing [12].…”