报告题目：传热系数能量平衡测定法在镁合金AJ62挤压铸造壁厚变化过程中的应用

报告题目（英文）：Determination of Heat Transfer Coefficients by Energy Balance Method in Squeeze Casting of Magnesium Alloy AJ62 with Variation in Wall Thicknesses

报告内容简介：Magnesium alloys have been widely used in today’s automotive and aerospace industry due to its light weight characteristic. Magnesium is one-third lighter than aluminum and three-quarters lighter than zinc and four-fifths light than steel. Squeeze casting with the advantage of pressurized solidification, close dimensional tolerance and good surface finish has been widely used for complex shape casting. During the solidification process, the applied pressure feeds the liquid metal into the air or shrinkage porosities effectively. It makes castings free of porosity with excellent as-cast quality. In today’s foundry, numerical simulation improved the productivity significantly. However, one of the most important parameter, the interfacial heat transfer coefficients (IHTCs) at the metal-mold interface is usually roughly set in the available finite element method (FEM) or finite difference method (FDM)-based commercial codes. To ensure to accurately determine the solidification path, microstructure development and shrinkage porosity formation etc., it is necessary to have a precise prediction of boundary conditions. In the real-life casting process, the imperfection of the contact between the mold and liquid metal due to the air gap caused by the application of coating on die surface may decrease the heat transfer between metal and die as well as cooling rate of the casting surface. This thermal barrier could degrade casting quality and properties significantly. Therefore, an accurate prediction of IHTC is critical to simulate the solidification process. Many research works have been done to determine the interfacial heat transfer coefficient under different casting conditions. However, most of the attentions have been placed on permanent mold casting or high pressure die casting processes. There is very limited knowledge about estimation of IHTC during squeeze casting. In this study, a step casting of magnesium alloy AJ 62 with wall thicknesses of 2, 4, 8, 12 and 20mm was prepared by squeeze casting technique under an applied pressure of 60MPa in a hydraulic press. The interfacial heat transfer coefficient (IHTC) between the die and casting was determined from the temperature measurement inside the casting and throughout the die at a distance of 2 and 4mm to the die surface. The temperature readings were recorded by fine type-K thermocouples. Based on the thermal gradient, the heat flux (q) and IHTC were evaluated using the energy balance method. The results showed that the IHTC between the metal and die surface increased rapidly right after the liquid metal was filled into the mold cavity and decreased as the solidification process proceeded. As the casting cross section thickness increased, the peak values of the interfacial heat transfer coefficientsrose.

报告人姓名：胡宏发教授

报告人简介(中文)：胡宏发教授在1981-1985年间在上海大学(延长路校区)完成本科学习；1989-1991年间在加拿大温莎大学攻读并取得硕士学位；1991-1996年间在加拿大多伦多大学攻读并取得博士学位；1996-1997年在加拿大魁北克镁合金技术研究所工作；1997-1999年在加拿大 Meridian 科技公司任首席冶金专家；1999-2000年在美国 Ryobi 压铸公司工作；2000年起在加拿大加拿大蕰沙大学机械汽车材料系工作，2006年被评为终身教授。他在1995年至1997年间曾与加拿大自然科学工程研究委员会合作完成多项研究。他撰写的论文超过140篇, 覆盖研究领域包括镁合金，复合材料，金属铸造，计算机模拟和物理冶金学。他现任冶金材料学报，加拿大自然科学工程研究委员会，自然科学基金 （美国），加拿大冶金季刊 的主审。他还曾担任很多学术会议，比如，加拿大采矿冶金协会，美国铸造协会，以及美国汽车研究协会 相关分会 的主席。目前的研究方向是轻金属及其合金的加工和评估。他基本的研究主要集中在 凝固，轻合金铸造的建模及数值模拟,相变和分解动力机制。他的应用研究包括镁合金在汽车领域的应用，新材料的铸造过程和成本效益。他在轻金属及其合成材料方面的研究工作已经引起几大汽车公司的注意。  

报告人单位(中文)：Department of Mechanical, Automotive & Materials Engineering, University of Windsor

报告时间：2015-10-20 09:30

报告地点：日新楼410

主办单位：上海大学材料学院

联系人：陈湘茹