本文選題：AZ31鎂合金 + 軋制��； 參考：《哈爾濱工業(yè)大學(xué)》2017年博士論文

【摘要】：鎂合金具有廣泛的應(yīng)用前景,尤其在航空、航天及汽車工業(yè)等領(lǐng)域,可以作為替代鋼和鋁合金部件的輕質(zhì)材料。但是由于其密排六方的晶體結(jié)構(gòu),在室溫條件下伸長率和成形性都很差,限制了其廣泛的應(yīng)用。因此,探索出一條既能獲得良好性能,又適用于工業(yè)化生產(chǎn)的鎂合金制備工藝,有利于促進鎂合金的應(yīng)用和發(fā)展。本文以目前應(yīng)用最廣泛的AZ31鎂合金為研究對象,以最簡單的雙輥同步軋制為研究手段。系統(tǒng)研究了 AZ31鎂合金鑄態(tài)板坯的多道次降溫?zé)彳埞に?多道次連續(xù)溫軋工藝和大道次變形量的多道次冷軋工藝。同時分析了 AZ31鎂合金板材單道次軋制過程中軋制溫度和道次變形量對板材的組織演化和力學(xué)性能的影響規(guī)律。詳細分析了 AZ31鎂合金軋制板材的微觀組織(如晶粒尺寸,位錯密度和孿晶等)、織構(gòu)(織構(gòu)強度和平均Schmid因子)對板材力學(xué)性能的影響。成功制備出屈服強度為357 MPa,抗拉強度為393 MPa的高強度AZ31鎂合金板材。得到了單道次冷軋變形量大于41%并且板形良好的AZ31鎂合金薄板,實現(xiàn)了 AZ31鎂合金板材的大道次變形量冷軋工藝。通過本文的研究探索出了一條適合于工業(yè)化、大批量生產(chǎn)的AZ31鎂合金薄板的軋制工藝路線。采用不同道次變形量(15%、20%、25%和30%)的多道次降溫?zé)彳埞に?對厚度為26 mm的AZ31鎂合金鑄態(tài)板坯進行開坯軋制,得到厚度為4 mm的終軋板材。軋制后得到的板材與初始鑄態(tài)板坯相比,晶粒得到顯著的細化,力學(xué)性能得到明顯的改善。當(dāng)?shù)来巫冃瘟繛?0%時,軋制板材的平均晶粒尺寸最小為21.5μm,此時板材具有最高的伸長率24.7%,同時具有126.1MPa的屈服強度及242 MPa的抗拉強度。綜合考慮生產(chǎn)效率,應(yīng)優(yōu)先選用30%的道次變形量進行AZ31鎂合金板材多道次降溫?zé)彳垖嶒灐Ｏ到y(tǒng)研究了軋制溫度為150-300 ℃,道次變形量為10-60%的AZ31鎂合金單道次軋制工藝及軋制板材的微觀組織及力學(xué)性能的演化規(guī)律。隨著道次變形量的增大,板材的織構(gòu)類型會經(jīng)歷形變織構(gòu)→混合織構(gòu)(形變織構(gòu)+再結(jié)晶織構(gòu))→再結(jié)晶織構(gòu)的轉(zhuǎn)變。織構(gòu)強度隨著軋制溫度的升高逐漸減弱,而隨著道次變形量的增大呈現(xiàn)先減小后增大的趨勢。采用大的道次變形量和低的軋制溫度可以獲得組織更加細小的板材。當(dāng)軋制溫度為250 ℃時,板材的組織細化效果最明顯,并且組織均勻性良好;當(dāng)?shù)来巫冃瘟吭?0-40%范圍內(nèi)時,板材具有最優(yōu)的力學(xué)性能。同時成功制備出屈服強度為357 MPa,抗拉強度為393 MPa的高強度AZ31鎂合金板材。分析了平均晶粒尺寸和平均Schmid因子對板材力學(xué)性能的影響,提出考慮了平均Schmid因子的Hall-Petch關(guān)系式:σ_(s-t)=(0.3/mt(σ_0+kd~(-1/2)),該公式反映了板材的組織和織構(gòu)共同作用下屈服強度的變化規(guī)律。通過理論計算,量化了固溶強化,晶界強化和位錯強化三種強化機制對軋制板材強度的貢獻。同時分析了導(dǎo)致軋制板材力學(xué)性能各向異性的原因。除了織構(gòu)的影響外,由于位錯的分布具有方向性,垂直于該方向變形會比沿著該方向變形使位錯產(chǎn)生更多的纏結(jié),因此進一步影響了板材力學(xué)性能的各向異性。另外,引入了方向性因子κ = f(ε),基于實驗擬合，，當(dāng)κ在軋制方向取為1,在橫向取為κ = 1 + 1n(h/H)時,理論計算得到的強度值與實驗值符合的很好。為了進一步提高AZ31鎂合金薄板的軋制效率,改善其板形質(zhì)量,基于織構(gòu)組織的控制,研究了 AZ31鎂合金板材的大道次變形量冷軋工藝。通過設(shè)計合理的多道次降溫?zé)彳埞に嚰岸嗟来芜B續(xù)溫軋工藝,得到了織構(gòu)強度很弱(僅為一般軋制板材的1/3-1/2)且大部分晶粒處于軟取向的2 mm厚AZ31鎂合金薄板。利用此板材進行單道次冷軋實驗,最大的道次變形量可以達到41%。經(jīng)過三道次冷軋,兩次中間退火和一次最終退火可以獲得厚度為0.55 mm,屈服強度為150 MPa,抗拉強度為300 MPa,伸長率接近20%的板形良好的AZ31鎂合金薄板。使AZ31鎂合金室溫單道次冷軋變形量提高了近3倍,極大的提高了鎂合金的冷軋生產(chǎn)效率。
[Abstract]:Magnesium alloys have wide application prospects, especially in the fields of aviation, aerospace and automobile industry, which can be used as light materials to replace steel and aluminum alloy components. However, because of their six square crystal structure, their elongation and formability at room temperature are very poor, limiting their wide application. Therefore, the exploration of one of them is good to obtain good results. The performance, which is also suitable for the preparation of magnesium alloys produced in industrial production, is conducive to the application and development of magnesium alloys. This paper takes the most widely used AZ31 magnesium alloy as the research object and the simplest double roll synchronous rolling as the research means. The multi pass cooling and hot rolling process of the AZ31 magnesium alloy slab is systematically studied. The multi pass cold rolling process of the continuous rolling process and the amount of the main road deformation was used. The influence of the rolling temperature and the pass deformation amount on the microstructure evolution and mechanical properties of the AZ31 magnesium alloy sheet during the single pass rolling process was analyzed. The microstructure of the AZ31 magnesium alloy rolled sheet (such as grain size, dislocation density and twin crystal) was analyzed in detail. The effect of texture (texture strength and average Schmid factor) on the mechanical properties of the plate was achieved. A high strength AZ31 magnesium alloy sheet with a yield strength of 357 MPa and a tensile strength of 393 MPa was successfully prepared. The AZ31 magnesium alloy sheet with a single pass cold rolling greater than 41% and a good plate shape was obtained, and the main road deformation of the AZ31 magnesium alloy sheet was realized. In this paper, the rolling process of a AZ31 magnesium alloy sheet suitable for industrialization and mass production is explored. A multi pass cooling hot rolling process with different pass deformation (15%, 20%, 25% and 30%) is used to roll the blank of AZ31 magnesium alloy slab with a thickness of 26 mm, and the thickness is 4 mm. Compared with the initial cast slab, the grain obtained is significantly refined and the mechanical properties are obviously improved. When the amount of the pass deformation is 30%, the average grain size of the rolled sheet is 21.5 m, the maximum elongation of the plate is 24.7%, and the yield strength of 126.1MPa and the tensile strength of 242 MPa are at the same time. Strength. In consideration of production efficiency, a multi pass cooling and hot rolling test of AZ31 magnesium alloy sheet should be selected with priority of 30% pass deformation. The single pass rolling process of rolling temperature of 150-300, AZ31 magnesium alloy with pass deformation amount of 10-60% and the evolution law of microstructure and mechanical properties of the rolled sheet are studied. The texture type of the sheet will undergo the transformation of deformation texture to mixed texture (deformation texture + RECRYSTALLIZED TEXTURE) and recrystallization texture. The texture strength decreases with the increase of rolling temperature, but decreases and then increases with the increase of the amount of pass deformation. The large amount of channel deformation and low rolling temperature are adopted. When the rolling temperature is 250 C, the microstructure refinement effect is the most obvious, and the organization uniformity is good. When the volume of the pass deformation is within the range of 30-40%, the plate has the best mechanical properties. At the same time, the high strength AZ31 magnesium alloy with the yield strength of 357 MPa and the tensile strength of 393 MPa is prepared. The influence of average grain size and average Schmid factor on the mechanical properties of sheet metal was analyzed. The Hall-Petch relation formula of mean Schmid factor was considered: sigma S-T = (0.3/mt (_0+kd~ (-1/2)). The formula reflected the variation of yield strength under the joint action of the structure and texture of the plate. The solution was calculated and the solution was quantified by theoretical calculation. The contribution of three intensification mechanisms of strengthening, grain boundary strengthening and dislocation strengthening to the strength of rolled sheet. At the same time, the reason for the anisotropy of the mechanical properties of the rolled sheet was analyzed. Besides the influence of texture, the distribution of the dislocation was directional, and the deformation in this direction would cause more tangles than the deformation along that direction. This further affects the anisotropy of the mechanical properties of the plate. In addition, the directional factor kappa = f (epsilon) is introduced. Based on the experimental fitting, when kappa is 1 in the rolling direction and when kappa = 1 + 1n (h/H) is taken laterally, the calculated strength values are in good agreement with the experimental values. In order to further improve the rolling efficiency of the AZ31 magnesium alloy sheet, the improvement of the rolling efficiency is improved. Under the control of texture structure, the cold rolling process of AZ31 magnesium alloy sheet is studied. By designing reasonable multi pass cooling hot rolling process and multi pass continuous warm rolling process, the texture strength is very weak (only 1/3-1/2 of general rolling plate) and 2 mm thick AZ31 magnesium with the most grain in soft orientation Alloy sheet. Using this sheet for single pass cold rolling experiment, the maximum pass deformation amount can reach 41%. after three pass cold rolling, two intermediate annealing and one final annealing can obtain the AZ31 magnesium alloy thin plate with thickness of 0.55 mm, yield strength 150 MPa, tensile strength 300 MPa, and elongation of close to 20%. The deformation of alloy at room temperature single pass cold rolling increased by nearly 3 times, which greatly improved the cold rolling production efficiency of magnesium alloy.

【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TG339;TG146.22

【參考文獻】

相關(guān)期刊論文 前10條

1 張堅;曹富榮;;多向鍛造法細化鎂合金晶粒的研究現(xiàn)狀[J];精密成形工程;2016年05期

2 魏琳俊;楊壽智;夏偉軍;鄧朝暉;劉靈;;鎂合金板材特殊軋制技術(shù)的研究進展[J];機械工程材料;2012年11期

3 張丁非;方霖;劉郭平;戴慶偉;;鎂合金板材軋制技術(shù)與工藝的研究進展[J];兵器材料科學(xué)與工程;2010年05期

4 張兵;袁守謙;張西鋒;呂爽;王超;;累積復(fù)合軋制對鎂合金組織和力學(xué)性能的影響[J];中國有色金屬學(xué)報;2008年09期

5 張文玉;劉先蘭;;異步軋制技術(shù)及其在鎂合金中的應(yīng)用[J];鍛壓技術(shù);2008年02期

6 萬玉剛;呂保義;康永林;王朝輝;蔡慶伍;張濟山;;退火工藝對溫軋AZ31板組織、織構(gòu)及性能的影響[J];稀有金屬;2007年04期

7 陳振華;許芳艷;傅定發(fā);夏偉軍;;鎂合金的動態(tài)再結(jié)晶[J];化工進展;2006年02期

8 程永奇,陳振華,夏偉軍,傅定發(fā);等徑角軋制AZ31鎂合金板材的組織與性能[J];中國有色金屬學(xué)報;2005年09期

9 劉向陽;鎂合金壓鑄技術(shù)及應(yīng)用[J];輕金屬;2005年02期

10 李金鋒,耿浩然,楊中喜,王英姿,崔峰,孫春靜;釔對AZ91鎂合金組織和力學(xué)性能的影響[J];鑄造;2005年01期

相關(guān)博士學(xué)位論文 前3條

1 喬艷黨;純鎂溫軋與冷拉拔中的動態(tài)再結(jié)晶、織構(gòu)及性能的研究[D];哈爾濱工業(yè)大學(xué);2014年

2 陳文振;ZK61鎂合金薄板軋制與組織、織構(gòu)及性能研究[D];哈爾濱工業(yè)大學(xué);2013年

3 靳麗;等通道角擠壓變形鎂合金微觀組織與力學(xué)性能研究[D];上海交通大學(xué);2006年

相關(guān)碩士學(xué)位論文 前2條

1 唐寧;連續(xù)鑄軋AZ31B鎂合金板坯的組織結(jié)構(gòu)及退火行為[D];中南大學(xué);2008年

2 陶俊;織構(gòu)和晶粒尺寸對變形鎂合金AZ31力學(xué)性能的影響[D];南京理工大學(xué);2007年

本文編號：1794007