本文選題：等通道角擠壓 + 常規(guī)擠壓��； 參考：《西南交通大學(xué)》2017年碩士論文

【摘要】：鎂合金在可降解醫(yī)用材料領(lǐng)域具有巨大研究潛力與價(jià)值,但是當(dāng)前本課題組研發(fā)的Mg-Zn-Mn合金材料各方面均不能滿足實(shí)際應(yīng)用要求。旨在制備加工出高性能材料,本課題對(duì)Mg-Zn-Mn合金制備工藝及多種組織性能強(qiáng)化工藝進(jìn)行系統(tǒng)性地研究實(shí)驗(yàn),本文研究?jī)?nèi)容包括合金熔煉、鑄錠均勻化熱處理、擠壓工藝、等通道角擠壓工藝、以及配合退火工藝等5方面的內(nèi)容,經(jīng)過各項(xiàng)參數(shù)逐步對(duì)比優(yōu)化后,最終確定出在材料組織性能強(qiáng)化方面較合理的復(fù)合實(shí)驗(yàn)性工藝。本實(shí)驗(yàn)采用新真空感應(yīng)加熱設(shè)備,自帶水冷降溫。前后共使用140mm、90mm兩種不同直徑鑄模,當(dāng)澆注模具為140mm時(shí),所得鑄錠平均晶粒尺寸約為200μm,當(dāng)在直徑為90mm模具內(nèi)澆注,所得鑄錠平均晶粒尺寸約為100μm,組織及性能相對(duì)大直徑澆注更加優(yōu)異。經(jīng)合金相圖分析及XRD檢測(cè),該熔煉條件下所制備鑄錠為單向固溶體結(jié)構(gòu)。經(jīng)360℃/24h且熱處理前后鑄錠晶粒尺寸無較大改變,為最佳均勻化熱處理工藝。以直徑為140mm的鑄錠為原材料,研究了均在0.5 mm/s慢速擠壓條件下,經(jīng)250℃、300℃、330℃三種不同擠壓溫度擠壓后材料組織性能對(duì)比,證實(shí)擠壓溫度越低組織約細(xì)小,強(qiáng)度越高并且其耐腐蝕性能越好,拉伸斷裂特性仍為脆性的解理斷裂。新制備90mm直徑鑄錠為原始材料,分別設(shè)計(jì)了 0.5mm/s、1mm/s、1.5mm/s、2mm/s四種不同速度對(duì)比,經(jīng)擠壓后試樣表面質(zhì)量良好,實(shí)驗(yàn)結(jié)果表明擠壓速度越大所得材料強(qiáng)度越高,材料塑性越低。較高速度擠壓后晶粒尺寸相對(duì)低速擠壓試樣更大,細(xì)小晶粒包圍著較粗大晶粒。塑性在下一步強(qiáng)化工藝中具有更重要的作用,因此0.5mm/s的擠壓速度為最佳選擇。研究了擠壓路徑、擠壓速度、擠壓溫度、擠壓道次數(shù)這4種基本參數(shù)各自對(duì)該工藝的強(qiáng)化效果的影響。對(duì)比分析恒溫?cái)D壓與降溫?cái)D壓工藝證實(shí)降溫工藝更有利于材料性能強(qiáng)化,不同的擠壓速度擠壓出的試樣組織與性能均無較大差別,較高速度擠壓材料易產(chǎn)生裂紋,低速擠壓雖降低了效率卻提高了工藝穩(wěn)定性。在相同條件下對(duì)比A、BA、C、Bc 4種路徑,實(shí)驗(yàn)證明Bc路徑合金組織細(xì)化效率最高,經(jīng)Bc路徑擠壓后的試樣組織晶粒尺寸均勻,無大尺寸晶粒。隨著擠壓道次數(shù)的增加,材料晶粒逐步細(xì)化,耐腐蝕性能、硬度、抗拉強(qiáng)度及塑性等綜合性能經(jīng)過多道次擠壓后均得到大幅度強(qiáng)化,斷裂方式由解理斷裂向韌窩斷裂轉(zhuǎn)變。本論文對(duì)退火工藝也進(jìn)行了復(fù)合研究,經(jīng)多道次等通道角擠壓后的試樣再經(jīng)不同退火參數(shù)做退火處理,退火后的試樣雖由于晶粒二次長(zhǎng)大導(dǎo)致強(qiáng)度有不同程度下降,但是所有試樣伸長(zhǎng)率均提升,在220℃/6h條件下處理后,試樣伸長(zhǎng)率最高達(dá)40%,材料塑性顯著提高。
[Abstract]:Magnesium alloys have great potential and value in the field of degradable medical materials, but all aspects of Mg-Zn-Mn alloy materials developed by our team can not meet the practical application requirements. The purpose of this paper is to prepare and process high performance materials. In this paper, the preparation process of Mg-Zn-Mn alloy and various microstructures and properties strengthening processes are studied systematically. The research contents include alloy melting, ingot homogenization heat treatment, extrusion process, etc. After comparing and optimizing the parameters of the five aspects, such as equal channel angular extrusion process and annealing process, a reasonable composite experimental process for strengthening the microstructure and properties of the material was finally determined. In this experiment, a new vacuum induction heating equipment with water cooling temperature. Two different diameters, 140mm / 90mm, were used before and after the casting. When the casting mould was 140mm, the average grain size of the ingot was about 200 渭 m, and when the mold diameter was 90mm, the average grain size of the ingot was about 200 渭 m. The average grain size of the ingot is about 100 渭 m, and the microstructure and properties of the ingot are better than that of large diameter casting. The alloy phase diagram analysis and XRD test show that the ingot prepared under the melting condition is a unidirectional solid solution structure. After 360 鈩，

本文編號(hào)：1813325