AZ63镁合金累积叠轧组织演变与界面焊合机制研究
发布时间：2019-01-30 17:34
【摘要】：镁合金在电子通讯、汽车制造及航空航天等领域具有广阔的应用前景及发展潜力,被誉为“21世纪最具发展潜力的绿色工程材料”。镁合金密排六方的晶体结构使其在室温下塑性和韧性较差,成为制约其加工应用的关键问题。本文以AZ63镁合金为试验材料,采用累积叠轧工艺(Accumulative Roll Bonding,ARB)制备了镁合金板材,利用组织观察、力学性能测试等研究了累积叠轧工艺对镁合金板材界面焊合行为、组织及性能影响,获得了镁合金累积叠轧界面焊合机制与塑性变形机理以及晶粒细化机制,对丰富镁合金剧塑性变形理论、高性能镁合金板材生产与应用具有一定的理论依据和指导意义。在累积叠轧试验中,温度分别为250℃、300℃、350℃、400℃,每个温度下进行5个道次ARB变形。结果表明,累积叠轧工艺能够显著细化镁合金板材的显微组织、提高镁合金的强度和塑性,且随着道次的增加组织均匀性改善明显。其中,经ARB1变形后镁合金伸长率提升了44%、经ARB3变形后强度由232MPa提高到282MPa。变形温度和首道次变形量是制约界面结合质量的关键因素,适当提高加热温度、延长保温时间,可有效改善镁合金塑性变形能力、有利于界面焊合;多道次叠轧变形可有效改善界面焊合质量,累积叠轧的界面焊合机制为再结晶结合机制。在镁合金累积叠轧变形初期,孪生发挥着重要作用,由于孪晶的产生能够促进基面滑移的开动,同时激发了大量再结晶,进而导致剪切带的产生。随着变形程度的增加,剪切带可通过扩展和宽化容纳更多外部变形,提高材料塑性变形能力。在变形持续累积到ARB3后,再结晶程度增加,取代剪切带组织。结合镁合金塑性变形机理和再结晶形核机制,建立了孪晶诱导再结晶形核模型。在孪晶交错处更容易造成应力集中,为再结晶提供形变储能,使孪晶界成为有效形核点。孪晶相互交叉作用越强烈,有利的形核位置就越多,进一步促进再结晶,组织的细化效果更显著。对于AZ63镁合金的累积叠轧工艺,其晶粒细化过程主要受孪晶诱导再结晶和动态再结晶共同控制。
[Abstract]:Magnesium alloys have a broad application prospect and potential in the fields of electronic communication, automobile manufacturing and aerospace, and are known as "the most potential green engineering materials in the 21st century". The crystal structure of dense hexagonal magnesium alloy makes its ductility and toughness poor at room temperature, which is a key problem restricting its processing and application. In this paper, AZ63 magnesium alloy was used as the experimental material and the cumulative stacked rolling process (Accumulative Roll Bonding,ARB) was used to prepare the magnesium alloy sheet. The bonding behavior of the cumulative stacked rolling process on the interface of magnesium alloy sheet was studied by means of microstructure observation and mechanical property test. The effect of microstructure and properties on the bonding mechanism, plastic deformation mechanism and grain refinement mechanism of accumulative stacking interface of magnesium alloy were obtained, which enriched the theory of superplastic deformation of magnesium alloy. The production and application of high-performance magnesium alloy sheet has certain theoretical basis and guiding significance. In the cumulative rolling test, the temperatures are 250 鈩，
本文编号：2418353
[Abstract]:Magnesium alloys have a broad application prospect and potential in the fields of electronic communication, automobile manufacturing and aerospace, and are known as "the most potential green engineering materials in the 21st century". The crystal structure of dense hexagonal magnesium alloy makes its ductility and toughness poor at room temperature, which is a key problem restricting its processing and application. In this paper, AZ63 magnesium alloy was used as the experimental material and the cumulative stacked rolling process (Accumulative Roll Bonding,ARB) was used to prepare the magnesium alloy sheet. The bonding behavior of the cumulative stacked rolling process on the interface of magnesium alloy sheet was studied by means of microstructure observation and mechanical property test. The effect of microstructure and properties on the bonding mechanism, plastic deformation mechanism and grain refinement mechanism of accumulative stacking interface of magnesium alloy were obtained, which enriched the theory of superplastic deformation of magnesium alloy. The production and application of high-performance magnesium alloy sheet has certain theoretical basis and guiding significance. In the cumulative rolling test, the temperatures are 250 鈩，
本文编号：2418353
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