Nimonic80A高温流变行为研究

摘要高温合金材料作为基础材料广泛参与国家重大工程的建设与高端装备的制造中，是运用于航空领域中的重要结构材料，在航空发动机中具有重要作用，是目前国内外合金领域的研制热点之一。Nimonic80A合金拥有优异的高温强度、抗氧化性和耐腐蚀性能等综合特点，广泛用于航空航天、发电站和交通运输等领域的热端零部件。但由于合金化程度较高，高温合金材料在热加工过程出现变形抗力大、热加工参数窗口小、可加工性能差等特征，导致合金的热加工成形与组织控制困难，影响合金性能，成材率低。因此，如何在热加工过程控制与优化热力学参数以获得所需的组织，同时避免热加工缺陷的产生，已成为高温合金材料实际生产需要解决的关键问题和热加工性研究的热点。本文主要以Nimonic80A合金材料为研究对象，围绕高温合金在热加工过程的高温变形行为、本构模型的建立等问题进行了系统的研究，主要研究结果如下：(1)在Geeble-3500热模拟压缩试验机上，对Nimonic80A合金在1223~l473K的变形温度范围、0.00130.0s的应变速率范围进行圆柱体单轴热压缩试验，获得Nimonic80A合金的在不同热变形条件下的应力-应变曲线，分析该合金分别在不同变形程度、变形温度和应变速率下的高温变形行为特点。得出结论，随着应变的增大，流变应力不断增大，达到最大值后，流变曲线的应力将保持一个相对稳定的状态，符合镍基合金典型的动态再结晶型流变应力曲线特征。(2)基于热压缩试验数据，利用多元线性回归的方法分析构建了Arrhenius形式的本构方程，表示了变形参数之间的定量关系，并对其变形机理进行了较为系统的计算。计算获得Nimonic80A合金的热激活能Q值，为311.9358 kJ.mol-。该模型的相对误差AARE=,相关系数R=0.97,说明所构建的本构方程能够较为准确的预测不同变形条件下的流变应力。关键词：Nimonic80A合金、热变形行为、本构模型、Arrhenius形式AbstractSuperalloy plays an important role in aero-engines and is one of the research hotspots inthe field of alloy at home and abroad.Nimonic80A alloy has excellent high temperaturestrength,corrosion resistance and oxidation resistance.It has been used in hot-endcomponents in aviation,aerospace,power station and transportation.In this paper,Nimonic80A round steel is taken as the research object,and the followingresearch work is carried out around the high temperature deformation mechanism of thealloy(1)The uniaxial hot compression tests of Nimonic80A alloy were carried out in thetemperature range of 1223 ~1473 K and the strain rate range of 0.001 ~30.0 s!on theGeeble-3500 thermal simulation compression testing machine.The stress-strain curves ofNimonic80A alloy under different hot deformation conditions were obtained,and the changesof microstructure after deformation were observed under optical microscope.(2)According to the obtained stress-strain data,the true stress-true strain curves underdifferent thermal deformation conditions were plotted,and the high temperature deformationbehavior characteristics of the alloy at different deformation degrees,deformationtemperatures and strain rates were analyzed.It is concluded that with the increase of strain,the flow stress increases continuously,and after reaching the maximum value,the stress of theflow curve will remain a relatively stable state.(3)According to the influence of different hot deformation parameters on the flow stress,the constitutive equation of Arrhenius form is analyzed by linear regression method,and thequantitative relationship between the deformation parameters is expressed.The thermalactivation energy Q value of Nimonic alloy was calculated to be 311.9358 KJ mol-1.Keywords:Nimonic80A alloy;hot deformation behavior;constitutive model;Arrhenius form目录第一章绪论…1.1引言.1.2高温合金概述11.2.1高温合金的分类….21.2.2高温合金的应用…21.2.3高温合金的发展…。.31.2.4高温合金研究现状.41.3高温合金的软化机制….41.4高温合金本构模型的研究.71.5材料变形抗力的测试方法…。.91.6本章小结….11第二章实验材料及实验方法.122.1引言..122.2实验材料.….122.3实验方法.122.3.1热压缩试验.132.3.2热物性参数测试….142.3.3实际热连轧过程142.4分析测试技术。.152.4.1OM观察..152.4.2电子背散射衍射….152.5本章小结…16第三章Nimonic80A高温流变行为研究…173.1引言.173.2 Nimonic8