【摘要】：鎂合金在電子通訊、汽車制造及航空航天等領(lǐng)域具有廣闊的應(yīng)用前景及發(fā)展?jié)摿?被譽為“21世紀(jì)最具發(fā)展?jié)摿Φ木G色工程材料”。鎂合金密排六方的晶體結(jié)構(gòu)使其在室溫下塑性和韌性較差,成為制約其加工應(yīng)用的關(guān)鍵問題。本文以AZ63鎂合金為試驗材料,采用累積疊軋工藝(Accumulative Roll Bonding,ARB)制備了鎂合金板材,利用組織觀察、力學(xué)性能測試等研究了累積疊軋工藝對鎂合金板材界面焊合行為、組織及性能影響,獲得了鎂合金累積疊軋界面焊合機制與塑性變形機理以及晶粒細化機制,對豐富鎂合金劇塑性變形理論、高性能鎂合金板材生產(chǎn)與應(yīng)用具有一定的理論依據(jù)和指導(dǎo)意義。在累積疊軋試驗中,溫度分別為250℃、300℃、350℃、400℃,每個溫度下進行5個道次ARB變形。結(jié)果表明,累積疊軋工藝能夠顯著細化鎂合金板材的顯微組織、提高鎂合金的強度和塑性,且隨著道次的增加組織均勻性改善明顯。其中,經(jīng)ARB1變形后鎂合金伸長率提升了44%、經(jīng)ARB3變形后強度由232MPa提高到282MPa。變形溫度和首道次變形量是制約界面結(jié)合質(zhì)量的關(guān)鍵因素,適當(dāng)提高加熱溫度、延長保溫時間,可有效改善鎂合金塑性變形能力、有利于界面焊合;多道次疊軋變形可有效改善界面焊合質(zhì)量,累積疊軋的界面焊合機制為再結(jié)晶結(jié)合機制。在鎂合金累積疊軋變形初期,孿生發(fā)揮著重要作用,由于孿晶的產(chǎn)生能夠促進基面滑移的開動,同時激發(fā)了大量再結(jié)晶,進而導(dǎo)致剪切帶的產(chǎn)生。隨著變形程度的增加,剪切帶可通過擴展和寬化容納更多外部變形,提高材料塑性變形能力。在變形持續(xù)累積到ARB3后,再結(jié)晶程度增加,取代剪切帶組織。結(jié)合鎂合金塑性變形機理和再結(jié)晶形核機制,建立了孿晶誘導(dǎo)再結(jié)晶形核模型。在孿晶交錯處更容易造成應(yīng)力集中,為再結(jié)晶提供形變儲能,使孿晶界成為有效形核點。孿晶相互交叉作用越強烈,有利的形核位置就越多,進一步促進再結(jié)晶,組織的細化效果更顯著。對于AZ63鎂合金的累積疊軋工藝,其晶粒細化過程主要受孿晶誘導(dǎo)再結(jié)晶和動態(tài)再結(jié)晶共同控制。
[Abstract]:Magnesium alloys have a broad application prospect and potential in the fields of electronic communication, automobile manufacturing and aerospace, and are known as "the most potential green engineering materials in the 21st century". The crystal structure of dense hexagonal magnesium alloy makes its ductility and toughness poor at room temperature, which is a key problem restricting its processing and application. In this paper, AZ63 magnesium alloy was used as the experimental material and the cumulative stacked rolling process (Accumulative Roll Bonding,ARB) was used to prepare the magnesium alloy sheet. The bonding behavior of the cumulative stacked rolling process on the interface of magnesium alloy sheet was studied by means of microstructure observation and mechanical property test. The effect of microstructure and properties on the bonding mechanism, plastic deformation mechanism and grain refinement mechanism of accumulative stacking interface of magnesium alloy were obtained, which enriched the theory of superplastic deformation of magnesium alloy. The production and application of high-performance magnesium alloy sheet has certain theoretical basis and guiding significance. In the cumulative rolling test, the temperatures are 250 鈩，

本文編號：2418353