本文關(guān)鍵詞： 鎂合金 AZ31B Arrhenius本構(gòu)方程 分步成形 二次拉伸　出處：《山東大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：鎂合金被譽(yù)為是21世紀(jì)最綠色、輕質(zhì)的金屬材料之一。由于鎂合金的比強(qiáng)度高,密度小,減震性能和電磁屏蔽性能優(yōu)越,因而在交通運(yùn)輸、電子設(shè)備及國(guó)防軍工中都有廣泛的需求和應(yīng)用前景。但鎂合金內(nèi)部為密排六方結(jié)構(gòu),滑移系較少,室溫下塑性成形能力較差,且變形過(guò)程中對(duì)于溫度、變形速率等條件要求相對(duì)較高,使其塑性變形工藝發(fā)展受到限制。為提高鎂合金塑性成形能力,擴(kuò)大鎂合金運(yùn)用領(lǐng)域,需要對(duì)鎂合金塑性成形工藝進(jìn)行研究和優(yōu)化。本構(gòu)方程是反映材料力學(xué)性能的重要參數(shù),描述了材料在變形過(guò)程中內(nèi)部應(yīng)力應(yīng)變的變化關(guān)系,在數(shù)值模擬中是設(shè)置模擬運(yùn)算的必要參數(shù),在實(shí)際生產(chǎn)中本構(gòu)關(guān)系也是各項(xiàng)生產(chǎn)參數(shù)設(shè)置的依據(jù),因此研究本構(gòu)關(guān)系對(duì)提高鎂合金塑性,優(yōu)化鎂合金變形工藝有重要意義。本構(gòu)方程模型種類較多,其中Arrhenius方程較適用于鎂合金板料變形。除此之外,拉伸實(shí)驗(yàn)是研究材料力學(xué)性能的重要手段,由于鎂合金內(nèi)部為密排六方結(jié)構(gòu),在室溫下塑性成形能力較差,因而采用分步拉伸實(shí)驗(yàn)對(duì)鎂合金板料進(jìn)行研究。分步拉伸實(shí)驗(yàn)將拉伸過(guò)程分成兩個(gè)或多個(gè)部分進(jìn)行,通過(guò)控制每個(gè)部分的變形條件來(lái)提高材料塑性成形能力。本文通過(guò)高溫拉伸實(shí)驗(yàn)對(duì)AZ31B鎂合金板料的本構(gòu)關(guān)系和分步成形性能進(jìn)行了研究,詳細(xì)分析了拉伸過(guò)程中材料力學(xué)性能的變化規(guī)律,討論了實(shí)驗(yàn)參數(shù)對(duì)鎂合金塑性變形的影響。論文主要研究?jī)?nèi)容如下:首先,通過(guò)單次高溫拉伸實(shí)驗(yàn)構(gòu)建了 AZ31B鎂合金板料Arrhenius本構(gòu)方程。拉伸溫度分別為423K、473K、523K、573K,變形速率分別為0.4s-1、0.1 s-1、0.01 s-1、0.001 s-1。該部分主要研究了 AZ31B鎂合金板料塑性成形的材料參數(shù),得到了Arrhenius本構(gòu)關(guān)系表達(dá)式。其次,進(jìn)行AZ31B鎂合金板料分步拉伸實(shí)驗(yàn),研究了溫度、拉伸速率及保溫時(shí)間對(duì)其塑性成形能力的影響。實(shí)驗(yàn)溫度設(shè)定為250℃-300℃,拉伸速率設(shè)定為1mm/min、0.3mm/min,保溫時(shí)間為30min。該部分借助控制變量的方法研究了不同參數(shù)對(duì)于鎂合金成形能力的影響情況,揭示了鎂合金塑性成形的變化規(guī)律。同時(shí)通過(guò)金相顯微組織觀察,分析了拉伸實(shí)驗(yàn)后AZ31B鎂合金斷口附近組織形貌,揭示了鎂合金板料塑性成形中內(nèi)部晶粒結(jié)構(gòu)的變化過(guò)程。
[Abstract]:Magnesium alloy is regarded as one of the greenest and light metal materials in 21th century. Because of its high specific strength, low density, excellent shock absorption and electromagnetic shielding performance, magnesium alloy is in transportation. Both electronic equipment and national defense military industry have wide demand and application prospect. However, magnesium alloy has a dense hexagonal structure, less slip system, poor plastic forming ability at room temperature, and temperature during deformation. The development of plastic deformation process is limited because of the relatively high deformation rate. In order to improve the plastic forming ability of magnesium alloy and expand the application field of magnesium alloy, It is necessary to study and optimize the plastic forming process of magnesium alloy. The constitutive equation is an important parameter to reflect the mechanical properties of materials. In the numerical simulation, it is necessary to set up the simulation operation parameters, and the constitutive relation is also the basis for the setting of the production parameters in the actual production. Therefore, the constitutive relation is studied to improve the plasticity of magnesium alloy. It is important to optimize the deformation process of magnesium alloy. There are many kinds of constitutive equation models, among which Arrhenius equation is more suitable for magnesium alloy sheet deformation. In addition, tensile test is an important means to study the mechanical properties of magnesium alloy. Due to the hexagonal structure inside magnesium alloy, the plastic forming ability of magnesium alloy is poor at room temperature, so the stepwise tensile test is used to study the sheet metal of magnesium alloy. The tensile process is divided into two or more parts by stepwise tensile test. The plastic forming ability of AZ31B magnesium alloy sheet was improved by controlling the deformation condition of each part. The constitutive relation and step forming property of AZ31B magnesium alloy sheet were studied by high temperature tensile test. The variation of mechanical properties of magnesium alloy during tensile process is analyzed in detail, and the influence of experimental parameters on plastic deformation of magnesium alloy is discussed. The main contents of this paper are as follows: firstly, The constitutive equation of AZ31B magnesium alloy sheet Arrhenius was constructed by a single high temperature tensile test. The tensile temperature was 423K / 473KN 523KN 523KN 573K, respectively, and the deformation rate was 0.4s-1n / 0. 1 / 1 / 0. 01 s / 1 / 0. 001 / s. The material parameters of AZ31B magnesium alloy sheet plastic forming were studied in this part. The constitutive expression of Arrhenius was obtained. Secondly, the effects of temperature, tensile rate and holding time on the plastic forming ability of AZ31B magnesium alloy sheet were studied. The experimental temperature was set at 250 鈩，

本文編號(hào)：1510870