Rolling Deformation And The Microstructure & Properties Of Magnesium Alloy Sheet By Multi-billet Extrusion Without Discard

Magnesium alloys have many advantages,such as low density,high specific strength and specific stiffness,good shock absorption and superior electromagnetic shielding performance.They are widely used in automotive,aerospace,communications and 3C products.The development of magnesium alloy sheets and strips,and the development of low-cost and high-efficiency extrusion-continuous rolling are important development directions in the field of magnesium alloys.Excessive extrusion is an extrusion technology that has been improved in recent years.Through the multiple blanks feeding and the welding connection of the front and back blank metal in the extrusion zone,the extrusion of the long-sized magnesium alloy slab is continuously output,and then rolled.Continuous and uninterrupted rolling of magnesium alloy sheet makes it possible.There is an extrusion bonding zone in the magnesium alloy sheet and strip with multiple blanks without extruding.Generally speaking,the performance of the joints of the magnesium alloy sheet and strip is lower than that of the base material.If the rolling deformation process is formulated according to the base material,it is easy to cause breakage.band.For the industrial production and rolling of magnesium alloy extruded plates,the material characteristics of the weakest areas must be considered,the microstructure and deformation behavior of the extruded joints must be studied,and the deformation behavior of the extruded joints at different rolling reductions must be determined.It is of great significance to establish and optimize the actual production process.In order to meet the needs of developing continuous rolling of magnesium alloy extruded sheet,the subject studied the deformation behavior of AZ31 magnesium alloy extruded slab during rolling,and focused on the evolution and performance of plastic deformation microstructure in the extruded connection area of multi-slab Variety.The initial AZ31 magnesium alloy sheet and strip obtained through the multi-slab unrefined extrusion connection was used to process the extruded connection plate in a multi-pass warm rolling process of 220 ° C to 280 ° C.By measuring and observing the thickness changes,metallographic structure,mechanical properties and hardness changes of the extruded-rolled plates at different reductions,the deformation behavior of the extruded joints during rolling was analyzed.The main results are as follows:(1)After analyzing the morphology and microstructure of the magnesium alloy sheet connected by multi-blank unrestrained extrusion,it is found that there are three typical forms of uneven thickness,uneven thickness distribution,and uneven microstructure in the front and back of the joint area.It has different effects on the shape of subsequent rolling.After research,it was found for the first time that the shape difference was small and the microstructure was different.After rolling,plate shape defects also appeared.(2)AZ31 extruded connection sheet did not break during tension rolling.The extruded joint and the base material were plastically deformed at the same time.The thickness of the plate was more consistent.The coarse grains of the extruded joint were broken and grew again.The unidirectional tensile fracture position of the plate is near the bonding area.The joint of the squeeze joint is in an unstable deformation stage.After several passes of rolling,the strength is also greatly improved,and the strength of the rolled deformed extruded joint reaches 91% of the base metal.(3)According to the research results,the technical requirements for the extruded billets required for extrusion-coil rolling were summarized and formulated.It is clear that for extruded billets,intermediate waves will be generated during rolling when the thickness difference is greater than 10% and cannot be eliminated.When the thickness difference is less than 5%,the wave shape of the plate will also be caused by uneven distribution,but it will vary with the rolling process.Perform gradual elimination.(4)The continuous extrusion process is reasonably applied to the continuous rolling process of magnesium alloys to achieve the heavy coil rolling of magnesium alloy strips and then improve the productivity as well as its automation control.