新型高强铝合金锻造工艺实验与模拟研究

【作者】 王亮；

【导师】 刘建生； 陈慧琴；

【作者基本信息】 太原科技大学 ， 材料加工工程， 2010， 硕士

【摘要】 Al-Zn-Mg-Cu高强铝合金厚板是现代航空、航天及武器装备等领域必不可少的关键结构材料。但是我国在大规格高强铝合金厚板锻件的加工理论及技术方面的基础研究相对薄弱,高性能铝合金厚板大部分依赖进口,严重制约了我国航空、航天及国防技术的发展。因此,深入研究高性能铝合金厚板锻造技术,对我国航空、航天及国防事业的发展具有重要的意义。本文针对一种新型Al-Zn-Mg-Cu超高强铝合金,系统研究了该合金的热变形特性及厚板的多向锻造工艺,具体研究内容及结果有:1.采用Gleeble-1500D热力模拟试验机,研究了变形温度250℃～450℃,变形速率0.001s-1～0.1s-1的条件下,Al-Zn-Mg-Cu合金的热压缩流变应力行为;分析了变形温度、变形速率对材料流变应力的影响规律,并建立了该合金高温变形时的流变应力本构方程;通过热拉伸实验,研究了变形温度250℃～450℃,变形速率0.1s-1条件下合金的拉伸性能。获得材料在250℃～450℃的拉伸强度、延伸率及断面收缩率,在此基础上建立了材料的热加工塑性图,并确定合金的锻造温度范围为420℃～350℃。2.采用热力模拟试验和金相实验方法,分析了该合金热压缩变形的组织演变规律。结果表明,Al-Zn-Mg-Cu合金是一种动态回复型金属,动态软化机制以动态回复为主。3.采用Deform-3D模拟了多向锻造工艺中的镦粗、拔长等工序,优化了髙径比、砧宽比及压下量等控制参数。制定了三镦两拔(方案一)和四镦三拔(方案二)两种多向锻造工艺方案,并对两种方案缩比件的多工序多向锻造过程进行了数值模拟。模拟结果表明,方案二总锻比为17.86,锻件内部等效应变达到12.6,方案一总锻比为13.34,锻件内部等效应变达到9.23。两套工艺方案缩比件的工艺实验检测结果表明:两种工艺方案锻件的拉伸强度都超过了500MPa,延伸率、断面收缩率等都达到使用要求。因此,采用三镦两拔的工艺方案,不仅可以生产合格的Al-Zn-Mg-Cu合金厚板锻件,而且可以简化锻造工序,降低生产成本。4.生产尺寸铝合金厚板锻造过程模拟结果表明,采用三镦两拔的锻造工艺进行厚板锻件的生产,设计总锻比在13～15时,锻件内部大部分区域等效应变达到9.96。实际尺寸铝合金厚板在西南铝成功试制,各项性能均达到使用要求。更多还原

【Abstract】 The thick plates of Al-Zn-Mg-Cu aluminum alloys with high strength are of indispensable structural materials in the industry of aerospace and armors. However, given the condition of relatively scant basic research on the theory and technology for processing the specifically thick-plate forgings of aluminum alloy, mostly causing the massive importation in high-performance thick plates of aluminum alloy, which restrains the technical development of aerospace and defense in our country definitely. Therefore, it is provident in the more accurate research on forging technology of aluminum alloy thick plates with high performance, which will facilitate our nation defense including aerospace industry and make sense totally.Concerning a new aluminum alloy of Al-Zn-Mg-Cu with high performance, this present thesis involves a scientifically research on the alloy’s property of thermal deflection and multi-forging technology of thick plates. The procedures and results in the research are represented following:1.The flow stress behavior of hot compression in Al-Zn-Mg-Cu alloy was investigated with Gleeble-1500D Thermal simulator under a temperature range of 250℃~450℃and a rate of deformation from 0.001s-1 to 0.1s-1; the regular influence resulted from the change of flow stress conducted by temperature and stain rates was concluded and then help form the flow stress constitutive equations when thermal deflection occurred in this alloy; through the hot tensile test, alloy’s tensile property was measured on the temperature from 250℃to 450℃and rate in 0.1s-1 of deformation. Hence, the material tensile strength, elongation and area reduction rate when worked from 250℃to 450℃founded the material thermal processing plasticity chart and ensured the forging temperature range in the real of 420℃~350℃.2.Microstructure revolution of hot compression in this alloy was deduced by means of thermal simulation and metallographic test. The conclusion indicates that the alloy of Al-Zn-Mg-Cu belongs to dynamic recovery metal, and that dynamic recovery is optimal in dynamic restoration mechanism. 3.The optimization of control parameters such as H0/D0, tool width ratio and reduction, as well as the simulation of multi-directional forging process containing upsetting and stretching were performed by Deform-3D. Multi-process multi-directional forging process of scale-down stock in two proposals embracing the first of threetimes-upstting with twice-stretching and the second of fourtimes-upstting with threetimes-stretching was simulated numerically. The results of simulation shows that: the total forging ratio is 17.86, equivalent strain in the forging reaches up to 12.6 in the first proposal; while the figure emerges at 13.34 and 9.23 respectively in the second one. The test results of experiment focused in scale-down stock in both technical proposals suggest that: tensile strength of forging surpasses 500 Mpa, elongations and reductions of cross section satisfy the application. Thus, the technical proposal of threetimes-upstting with twice-stretching not only enables the generation of Al-Zn-Mg-Cu alloy thick plate forging, but also simplifies the forging process and decreases the cost.4. The simulation of forging process of aluminum alloy thick plate within real sizes implicates that, during the generation of thick plate forgings by the forging technology of threetimes-upstting with twice-stretching when the total forging ratio designed in the scope of 13~15, forging effective strain within most regions stains to 9.96. Aluminum alloy thick plate within real sizes was successfully fabricated in Southwestern Aluminum Fabrication Plant, of which all the properties are available in application.更多还原