【摘要】：晶粒細化是改善和提高金屬材料性能的有效途徑之一,目前采用大塑性變形方法制備細晶材料依然存在一些問題,如加工的工件尺寸較小,存在明顯的織構(gòu)傾向等。連續(xù)變斷面循環(huán)擠壓(Continuous Variable Cross-section Recycled Extrusion,CVCE)是制備大規(guī)格塊體細晶材料的一種新型大塑性變形方法,其操作相對簡單,生產(chǎn)效率高,并且在變形過程中能夠?qū)崿F(xiàn)變形體的均勻控制,有利于工業(yè)化生產(chǎn)的實現(xiàn)。本文對TC11合金進行連續(xù)變斷面循環(huán)擠壓變形,并對變形后的材料進行熱處理,研究了變形工藝參數(shù)以及熱處理制度對合金組織性能的影響,并采用DEFORM軟件對變形效果較好的一組工藝參數(shù)(850℃,6道次,5mm/s)試樣的溫度場、應(yīng)力場及應(yīng)變場進行模擬。主要研究內(nèi)容及結(jié)論如下:(1)采用不同的工藝參數(shù)對TC11合金進行連續(xù)變斷面循環(huán)擠壓,分析了變形溫度、變形道次、變形速度對其組織的影響。結(jié)果表明:當(dāng)變形溫度在再結(jié)晶溫度范圍內(nèi)時,隨著循環(huán)道次的增加,晶粒的細化程度以及均勻程度增加;而在較高溫度(950℃)變形時,TC11晶粒的細化程度先增大再減小。綜合分析,可獲得較優(yōu)的工藝參數(shù)為850℃,6道次,5mm/s,初生α相尺寸由10μm細化至4~4.5μm左右,細化效果較顯著,且組織分布均勻。1(2)研究了退火溫度及退火時間對連續(xù)變斷面循環(huán)擠壓變形后TC11合金組織結(jié)構(gòu)的影響。選擇接近再結(jié)晶的溫度進行雙重退火處理,變形工藝參數(shù)為850℃,6道次,2mm/s和850℃,6道次,5mm/s的最優(yōu)熱處理制度為:(850℃,1h,AC)+(530℃,1h,AC),初生α相尺寸為3~4μm,且晶界清晰,次生α相的等軸化程度增高。(3)利用透射電鏡觀察連續(xù)變斷面循環(huán)擠壓以及熱處理后試樣的微觀組織,揭示了組織的細化機理。結(jié)果表明,CVCE變形組織熱處理時主要是以再結(jié)晶實現(xiàn)晶粒細化。(4)采用DEFORM軟件對較優(yōu)的變形工藝參數(shù)(850℃,6道次,5mm/s)進行溫度場、應(yīng)力場及應(yīng)變場的模擬,變形過程中發(fā)生變形能和熱能之間轉(zhuǎn)換,隨著變形道次的增加應(yīng)變量不斷累積,變形道次為6時,試樣中間部位的累積應(yīng)變量可達到5.83~7.20,且分布較為均勻。
[Abstract]:Grain refinement is one of the effective ways to improve the properties of metal materials. At present, there are still some problems in the preparation of fine-grained materials by large plastic deformation, such as the smaller size of the workpiece processed, the obvious texture tendency and so on. Continuous variable section cyclic extrusion (Continuous Variable Cross-section Recycled Extrusion,CVCE) is a new kind of large plastic deformation method for the preparation of large size bulk fine grain materials. Its operation is relatively simple, and its production efficiency is high, and it can realize the uniform control of the deformable body during the process of deformation. It is conducive to the realization of industrial production. In this paper, the TC11 alloy was deformed by continuous cyclic extrusion with variable cross section, and the material after deformation was treated by heat treatment. The effects of deformation parameters and heat treatment system on the microstructure and properties of the alloy were studied. The temperature field, stress field and strain field of a group of process parameters (850 鈩，

本文編號：2202776