本文關(guān)鍵詞： 熱擠壓 Mg-6Al合金 顯微組織 力學(xué)性能　出處：《哈爾濱理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：擠壓作為變形鎂合金一種有效的塑性成形方式,可以顯著提高鎂合金的變形能力,獲得大變形量,進(jìn)而達(dá)到改善鎂合金組織并提高其性能的目的。影響變形鎂合金組織的因素較多,如擠壓速度、擠壓溫度、擠壓比及潤(rùn)滑條件等。本文以Mg-6Al合金為研究對(duì)象,通過(guò)光學(xué)顯微鏡、掃描電子顯微鏡、能譜分析以及拉伸試驗(yàn)等分析測(cè)試手段,系統(tǒng)研究了擠壓速度、擠壓溫度及擠壓比對(duì)Mg-6Al合金顯微組織和力學(xué)性能的影響規(guī)律。研究結(jié)果表明:均勻化態(tài)Mg-6Al合金晶粒的平均尺寸約為70μm。Mg-6Al合金的動(dòng)態(tài)再結(jié)晶分為形核和長(zhǎng)大兩個(gè)階段,且動(dòng)態(tài)再結(jié)晶晶粒多數(shù)在原始晶界和孿晶處形核。當(dāng)擠壓比為55,擠壓溫度為400℃時(shí),分別以10 mm/min、20 mm/min的擠壓速度對(duì)均勻化態(tài)Mg-6Al合金進(jìn)行熱擠壓。當(dāng)擠壓速度為10 mm/min時(shí),Mg-6Al合金中發(fā)生了不完全動(dòng)態(tài)再結(jié)晶,動(dòng)態(tài)再結(jié)晶晶粒的平均尺寸約為2μm。當(dāng)擠壓速度為20 mm/min時(shí),Mg-6Al合金中發(fā)生了完全動(dòng)態(tài)再結(jié)晶,動(dòng)態(tài)再結(jié)晶晶粒的平均尺寸約為3μm。當(dāng)擠壓速度范圍為10~40mm/min時(shí),擠壓速度的提高有利于促進(jìn)動(dòng)態(tài)再結(jié)晶的發(fā)生,隨著擠壓速度的提高,擠壓態(tài)Mg-6Al合金的抗拉強(qiáng)度及斷后伸長(zhǎng)率增大。當(dāng)擠壓溫度為400℃,擠壓速度為20 mm/min時(shí),分別采用8、22、55的擠壓比對(duì)均勻化態(tài)Mg-6Al合金進(jìn)行熱擠壓。隨著擠壓比的增大,Mg-6Al合金的組織更加均勻,動(dòng)態(tài)再結(jié)晶程度更大,且隨著擠壓比的提高,擠壓態(tài)Mg-6Al合金的抗拉強(qiáng)度及斷后伸長(zhǎng)率增大,當(dāng)擠壓比提高至55時(shí),Mg-6Al合金的抗拉強(qiáng)度達(dá)到275 MPa,斷后伸長(zhǎng)率達(dá)到27%。Mg-6Al合金的熱擠壓過(guò)程可分為三個(gè)階段:錠坯鐓粗階段、填充擠壓階段及基本擠壓階段。擠壓速度變化時(shí),Mg-6Al合金熱擠壓過(guò)程中的最大擠壓力及穩(wěn)態(tài)擠壓力與動(dòng)態(tài)再結(jié)晶密切相關(guān)。
[Abstract]:As an effective plastic forming method for wrought magnesium alloys, extrusion can significantly improve the deformation capacity of magnesium alloys and obtain a large amount of deformation. In order to improve the microstructure and properties of wrought magnesium alloys, there are many factors affecting the microstructure of wrought magnesium alloys, such as extrusion speed, extrusion temperature, extrusion ratio and lubrication conditions. Scanning electron microscope (SEM), energy spectrum analysis (EDS) and tensile test were used to study the extrusion speed. The effect of extrusion temperature and extrusion ratio on microstructure and mechanical properties of Mg-6Al alloy is studied. The results show that the average grain size of homogenized Mg-6Al alloy is about 70 渭 m 路Mg-6Al. The dynamic recrystallization of the alloy is divided into two stages: nucleation and growth. And most of the dynamic recrystallization grains are nucleated at the original grain boundary and twin. When the extrusion ratio is 55 and the extrusion temperature is 400 鈩，

本文編號(hào)：1525274