Mechanical Behavior of Magnesium Experienced Severe Plastic Deformation
Chemical and Materials Engineering
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This thesis reviewed the development of processing technologies, including forging, rolling, extrusion and equal channel angular pressing (ECAP). Among these technologies, ECAP technology to process pure magnesium was studied. This thesis describes what ECAP technology is and reviews the current research status of ECAP processed pure magnesium.This thesis studied the effects of temperature, passes and post-heat treatment on microstructures and sample hardness. Across each sample, the microstructure was observed. Experiments were conducted at 350℃, 250℃ and 200℃ to study the microstructure change as a function of temperature. It was found that as the temperature was decreased, the average grain size also decreased. We fixed the temperature at 200℃ and used 1 pass, 2 passes, 4 passes and 8 passes to see the microstructure change right after pressing. The microstructure was altered significantly after post heat treatment. The more suitable post heat treatment for samples pressed at 200℃ with 8 passes, is 300℃ for 40 min with water cooling, by which we can get the smallest average grain size of 11.2 μm. The hardness was higher with more severe deformation, more passes, and lower pressing temperature, which has been increased more than 20% from 7.5HV right after pressing.