Effect of Gas Bubbling Filtration Treatment on Microporosity Variation in A356 Aluminium Alloy

作     者：Choongdo Lee Taeil So Kwangseon Shin 

作者机构：Department of Metallurgical & Materials EngineeringInha Technical College Magnesium Technology Innovation CenterDepartment of Materials Science and EngineeringSeoul National University 

出 版 物：《Acta Metallurgica Sinica(English Letters)》 (金属学报（英文版）)

年 卷 期：2016年第29卷第7期

页      面：638-646页

核心收录：

学科分类：080503[工学-材料加工工程] 08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0802[工学-机械工程] 080201[工学-机械制造及其自动化] 

基　　金：supported by the General Researcher Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education,Science and Technology(2010-0022284) supported by the Development Program for Industrial Core-Technology through the Korea Evaluation Institute of Industrial Technology(KEIT) funded by the Ministry of Trade,Industry and Energy(10048817) 

主　　题：Aluminium alloy Microporosity Gas bubbling filtration process (GBF) Tensile property 

摘      要：In the present study, the contribution of the gas bubbling filtration （GBF） process to the microporosity variation, microstructural characteristics and tensile properties of A356 aluminium alloy was investigated. The test specimens were fabricated through gravity casting in terms of the process variables： the degassing time, the impeller rotation and the aperture size of gas inlet hole. The density measurement and scanning electron microscope fractography analyses were conducted to evaluate the variation of the volumetric porosity and fractographic porosity with the GBF process, respec- tively. The fractographic porosity of the specimens can be minimised under specific GBF conditions in terms of the buoyant velocity and the absorbing capacity of gas bubbles, the inclusion of oxide films, whereas the volumetric porosity can be wholly reduced on the lapse of degassing time. The ultimate tensile strength （UTS） and elongation at optimal conditions were improved to approximately 30 MPa and 1.5% compared with no GBF treatment. Even though an extension of the degassing time and/or excessive stirring action of the melt may induce the inclusion of bifilm oxides and the increase of fractographic porosity, the tensile properties of over-treated specimens were maintained to a level which is similar to those that did not undergo GBF treatment due to the grain refinement accompanying with the GBF process. In addition, the defect susceptibility of UTS and elongation to microporosity variation could be remarkably improved at an optimal GBF condition.