Research on the Forming Mechanism of Multi-mode Ultrasonic Assisted Equal Channel Angular Pressing for Ultrafine Grained 1070 Pure Aluminum

With its excellent mechanical properties, ultrafine grained metal materials are especially suitable for the micro plastic forming of small parts. Large plastic deformation method is a common method for preparing ultrafine grained metal materials. And the Equal Channel Angular Pressing（ECAP） method is considered as one of the most promising large plastic deformation methods.The traditional ECAP process requires multiple passes of strain accumulation to obtain ultra-fine grained metal materials, so the preparation efficiency of which is low. The combination of assisted ultrasonic vibration and ECAP process can effectively reduce the extrusion forming load and improve the preparation efficiency of ECAP. The existing research on ultrasonic assisted ECAP is mainly on the ultrasonic vibration of tool. The workpiece ultrasonic vibration assisted ECAP process is proposed and studied. The forming mechanism of 1070 pure aluminum ECAP process is made comparing study with two ultrasonic vibration modes. The influence rules of two different ultrasonic vibration modes on grain refining ability are also studied. The results show that the ultrasonic softening effects of tool vibration of and workpiece vibration are all improved with the increase of ultrasonic power, which can greatly reduce more ECAP forming force and improve the ability of refining grain of passes. The workpiece ultrasonic vibration mode can absorb more ultrasonic energy than the tool ultrasonic vibration mode, which can effectively improve the preparation efficiency of ultrafine grained metal materials.