Fabrication of Premium Magnesium Castings by Semi-solid Forming Process

采用半固态成型工艺制造优质镁铸件

基本信息

批准号：
11225207
负责人：
KAMADO Shigeharu
金额：
$ 41.98万
依托单位：
Nagaoka University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11225207/
关键词：
Mg-Zn-Al Alloy Semi-solid Forming Process filling into Thin Cavity Tensile Properties Focused Ultrasound In-Line Monitoring Porous Material Pulse Electric Current Sintering 薄肉充填性固相粒子の球状化時効特性成形性ミクロ組織

项目摘要

Our research group aims to establish elementary fabrication processes for high qualification of magnesium alloys using semi-solid forming process, including that for high performance raw materials. The results are summarizes as follows(1)In "Search for magnesium alloys having good fluidity and adequate tensile properties", the results show that high Zn and Al contents lead to an increase in the amount of compounds that crystallize at low temperatures and the heat generated from the eutectic reactions becomes so large that the semi-solid forming is possible at 465℃ and 535℃ in the alloys containing Al+Zn contents of 20mass% and 15mass%, respectively. These temperatures are more than 100℃ lower than die-casting temperature for conventional magnesium alloys. The addition of small amount of Ca or Sr remarkably refines the eutectic compounds, which are useful for fluidity at semi-temperatures, resulting in suitable elongation and comparable strength with conventional die-casting alloys.(2)M … More agnesium based porous materials are made by Pulse-Electric-Current-Sintering (PECS) method using cut chips. Commercial ingots of AZ91D and AM60B alloys and extruded AZ31 alloy were selected as raw materials in order to change th amount of eutectic compounds and the range of semi-solid temperatures. In well-joined parts of porous samples of AZ91D and AM60B alloy, Mg-Al compounds crystallize, while the aluminum content at the joined part of AZ31 porous sample is concentrated. This means that the non-equilibrium solidified Mg-Al compound is preferentially remelted by rapid heating during PECS. Thus the difference in the microstructures of the joined parts is caused by the different aluminum contents of the alloys. The condition for making the well-joined porous materials using PECS processi s to use alloys that have large amount of low melting compounds and large semi-solid temperature range, resulting in large absorbing energy in compressive test. The plateau stresses of the porous materials investigated in this study largely depend on pore ration in the range from 1.3 to 37.3MPa.(3)In "in-line monitoring of magnesium alloy melt by using focused ultrasound to aim at an in-situ detection of inclusions during liquid recycling process, it is found that an usage of metal-sprayed buffer rod and Focused Ultrasound with a frequency of 5MHZ enable to clearly detect reflected pulse echo from iron block even in a molten magnesium alloy.(4)In "production of magnesium alloys for semi-solid casting on the basis of spheroidizing mechanism of primary crystals", a newly developed processing route is applied in order to refine and to spheroidize primary crystals by insertinga rod, which acts as a nucleation site for primary crystals, into the molten metal and rotating it before solidified specimen. The primary crystals tend to float on the top surface of the molten metal because solid density is lower than the liquid. THerefore, the molten metal is stirred using an inverted T-shaped rod near the bottom of the melt and followed by decreasing the solidification time at the temperature interval from recalescance to quenching. As a result, this process successfully produces an ingot having homogenous fine and spherical primary crystals with an average grain size of 73μm Less

我们的研究小组旨在使用半固体形成过程（包括高性能原材料）来建立高质量镁合金的基本制造过程。 The results are summarizes as follows(1)In "Search for magnesium alloys having good fluidity and adequate tensile properties", the results show that high Zn and Al contents lead to an increase in the amount of compounds that crystallize at low temperatures and the heat generated from the eutectic reactions become so large that the semi-solid forming is possible at 465℃ and 535℃ in the alloys containing Al+Zn含量分别为20mass％和15mass％。对于常规镁合金，这些温度比压铸温度低100升以上。添加少量的Ca或SR可以显着完善共晶化合物，这些化合物可用于半温度时的流动性，从而与常规的模具铸造合金相当。选择AZ91D和AM60B合金和挤出AZ31合金的商业诱导作为原材料，以更改共晶化合物的量和半固体温度的范围。在AZ91D和AM60B合金的多孔样品中加入的部分中，MG-AL化合物结晶，而AZ31多孔样品的连接部分的铝含量被浓缩。这意味着，非平衡固化的MG-AL化合物优选通过PEC中的快速加热来重新降低。联合部分的微观结构的这种差异是由合金的不同铝含量引起的。使用PECS工艺制作良好的多孔材料的条件，使用具有大量低熔化化合物和较大半固体温度范围的合金，从而在压缩测试中导致大量吸收能量。 The plateau stresses of the porous materials investigated in this study largely depend on pore ration in the range from 1.3 to 37.3MPa.(3)In "in-line monitoring of magnesium alloy melt by using focused ultrasound to aim at an in-situ detection of inclusions during liquid recycling process, it is found that an usage of metal-sprayed buffer rod and Focused Ultrasound with a frequency of 5MHZ enable即使在熔融镁合金中清楚地检测到从铁块中清楚地检测出反射的回声。固化的样品。由于固体密度低于液体，固体晶体倾向于漂浮在熔融金属的顶部。结果，此过程成功地产生了具有同质细胞和球形初级晶体，平均晶粒尺寸少73μm