Production-safe A356 Semi-solid Aluminum Alloy Research On Tissue Preparation

In the ordinary casting and solidification process,the aluminum alloy melt has the characteristics of filling turbulence,solidification shrinkage,etc.,which leads to defects such as abnormal coarse dendrites,bubbles,looseness and shrinkage in the microstructure of the molded part,especially for casting large castings.There will be problems such as coarse grain structure and serious segregation of components.These defects and deficiencies will reduce the yield,durability and fatigue resistance of the parts,which will greatly reduce the safety application range and safe service life of the parts,and limit the application of aluminum alloy molded parts in the transportation fields such as automobiles and high-speed rails.Semi-solid molding technology has great advantages in refining grain structure,reducing shrinkage porosity,reducing deformation re sistance,improving mold life,improving product performance,etc.,and the safety performance of the product is also higher,thus attracting many scholars to conduct research.For the flow forming,the semi-solid slurry preparation technology is the core key,but it is limited by the narrow solid temperature conditions of the semi-solid slurry solid temperature change.Most mechanical mixing equipment has serious adhesive gas and process.Problems such as poor stability,inefficiency,troublesome disassemb ly,cumbersome and cumbersome,and further scale applications have been limited.In response to these problems,this project has designed a new intensive cooling and agitation equipment,using a rod-shaped stirring shaft and liquid circulation cooling means to improve the efficiency of heat exchange and reduce the possibility of gas entrainment in the alloy liquid,which is beneficial to improve the product structure and performance of the equipment.Stable reliability and safety;and developed hydraulic cylinder lifting system and PLC control system to improve the degree of automation for human error,error and accuracy,and poor consistency of manual operation during equipment process control.It is beneficial to ensure the continuous and stable preparation of the slurry,improve the consistency of the process and products,ensure the safe and stable operation of the equipment and reduce the incidence of safety accidents.In addition,new smelting equipment with alarm devices have been designed and improved for the safety problems of conventional heating equipment.Aiming at the stirring speed,stirring time and different water cooling superposition stirring in the preparation process of aluminum alloy semi-solid slurry,the effects of various processes on t he grain size were analyzed.The size and shape of the grain size and shape were analyzed.Process parameters that are more reliable and stable in tissue performance.When the stirring speed is increased from 100r/min to 500r/min,the grain size decreases from 168?m to 105?m,the shape factor increases from 0.46 to 0.82,and the grain size decreases from 168?m to 98?m as the stirring time increases from 10 s to 30 s.The shape factor increased from 0.45 to 0.80.With the increase of superposition water cooling a nd stirring speed,the primary solid phase size decreased from 123?m to 84?m,and the shape factor increased from 0.70 to 0.88.These methods and processes can increase the number of grains.Improve grain morphology and organization.The temperature data in the pulping process was analyzed to study the mechanism of the relevant grain nucleation growth process.The mechanical properties of semi-solid aluminum alloys were studied by heat treatment and rolling process.Under the appropriate heat treatment process,the increase of aging temperature can effectively shorten the time required for aging.The tensile strength of semi-solid parts is higher than that of ordinary casting.About 55 Mpa,the elongation can be th ter-cooling process is 22 MPa higher than that of the waterless cooling,and the elongation is increased by 3.5%;the tensile deformation of the molded part under the process of increasing the stirring shaft speed The strength is increased by 23 MPa and the elongation is increased by4.0%.These processes can improve the mechanical properties of the board and obtain higher performance and safer products.