本文關(guān)鍵詞：AZ31B和7075攪拌摩擦焊接頭組織與力學(xué)性能研究　出處：《湖南大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： AZ31B鎂合金 7075鋁合金 攪拌摩擦焊 顯微組織 力學(xué)性能

【摘要】：鎂合金、鋁合金具有密度小、比強(qiáng)度高、切削加工性能優(yōu)良等優(yōu)點(diǎn),目前廣泛應(yīng)用于航空航天、電器電子、高速列車、汽車、船舶等行業(yè)。攪拌摩擦焊主要用于低熔點(diǎn)金屬及其合金的固態(tài)連接,在焊接的過程中不需要?dú)怏w保護(hù)、填充焊絲、無弧光輻射、煙塵和飛濺,且焊接頭內(nèi)不易產(chǎn)生氣孔、疏松和熱裂紋等缺陷,焊接接頭頭的力學(xué)性能較好,在實(shí)際生產(chǎn)中其設(shè)備易于操作,便于實(shí)現(xiàn)自動(dòng)化。本文主要研究了10mm厚AZ31B鎂合金和7075鋁合金板材同種合金FSW對(duì)焊,分析了在一定焊接工藝參數(shù)下焊接接頭的金相顯微組織、顯微硬度和力學(xué)性能,并通過改變軸肩下壓量分析其對(duì)焊縫質(zhì)量、組織結(jié)構(gòu)及接頭力學(xué)性能的影響,探索其內(nèi)在規(guī)律,得出以下結(jié)論：(1)分別實(shí)現(xiàn)了10mm厚AZ31B鎂合金板材攪拌摩擦焊接對(duì)焊和10mm厚7075鋁合金板材的攪拌摩擦焊接對(duì)焊,形成了外觀成型良好,微觀組織形態(tài)、力學(xué)性能優(yōu)良的焊接接頭。(2)增加軸肩下壓量至1.5mm時(shí),AZ31B鎂合金FSW焊縫表面更加細(xì)密、光滑、波紋狀組織更加連續(xù),且旋轉(zhuǎn)速度與焊接速度比值在28左右時(shí)增加軸肩下壓量會(huì)使這種趨勢(shì)更加明顯。(3)AZ31B鎂合金攪拌摩擦焊接頭的橫截面顯微硬度值總體呈現(xiàn)出“W”字形狀,沿中心線大致呈對(duì)稱分布,母材區(qū)硬度約為70HV,焊縫區(qū)硬度最高值達(dá)到67HV,出現(xiàn)在偏離焊縫中心的后退側(cè)焊核區(qū)。(4)軸肩下壓量從0.5mm增加到1mm時(shí),下壓量大小變化對(duì)接頭的抗拉強(qiáng)度和延伸率影響不大。而在軸肩下壓量從1mm增加到1.5mm時(shí),抗拉強(qiáng)度與延伸率都獲得了顯著的提升,在軸肩下壓量d=1.5mm時(shí)達(dá)到最大,此時(shí)抗拉強(qiáng)度和延伸率分別為213MPa及6.87%,分別比d=0.5mm時(shí)攪拌摩擦焊接頭提高了17.7%和29.4%。(5)在7075鋁合金對(duì)接接頭中,焊核區(qū)組織發(fā)生了完全動(dòng)態(tài)再結(jié)晶,其晶粒為細(xì)小的等軸晶粒。熱機(jī)械影響區(qū)前進(jìn)側(cè)的晶粒比后退側(cè)的晶粒長(zhǎng),而且晶粒不規(guī)整也不均勻。熱影響區(qū)的晶粒變化和熱機(jī)械影響區(qū)一致。(6)對(duì)7075鋁合金第二相粒子的分析結(jié)果表明：隨著軸肩下壓量的增加,焊核區(qū)的第二相粒子分布比母材區(qū)細(xì)小、均勻；而熱機(jī)械影響區(qū)的第二相粒子將會(huì)被拉長(zhǎng)和粗化；熱影響區(qū)第二相粒子逐漸變多。
[Abstract]:Magnesium alloy, Aluminum Alloy has low density, high specific strength, good cutting performance, is widely used in aerospace, electrical and electronic, high-speed train, automobile, shipbuilding and other industries. The friction stir welding is mainly used for solid connection with low melting point metal and alloy, the welding process does not require gas protection, filling no wire, arc radiation, dust and splash, and the welding head is not easy to produce pores, porosity and hot crack defects, mechanical properties of the welding joint head is good, in the actual production of the equipment is easy to operate, easy to realize automation. This paper mainly studies the 10mm thick AZ31B magnesium alloy and Al alloy 7075 Aluminum Alloy plate FSW analysis of the butt welding, microstructure of welded joints under certain welding parameters, microhardness and mechanical properties, and by changing the shoulder press amount on the weld quality, organization structure and joint Effect of mechanical properties, explore its inherent laws, draw the following conclusions: (1) were achieved by 10mm thick AZ31B magnesium alloy friction stir welding friction stir butt welding and butt welding of 10mm thick 7075 Aluminum Alloy plate, formed the appearance of good shape, microstructure and mechanical properties of welded joint with good (2). Increase the shoulder press amount to 1.5mm, the surface of AZ31B magnesium alloy FSW weld is more dense, smooth, corrugated tissue more continuous and rotational speed and welding speed ratio increases about 28 when the shoulder press amount will make this trend more obvious. (3) the friction welding head cross section microhardness values the whole show "W" shape mixing AZ31B magnesium alloy, along the center line roughly symmetrical distribution, hardness of base metal is about 70HV, the hardness of Weld Zone reached the highest value of 67HV, appeared in the deviation from the weld center back side nuclear welding. (4) under pressure from the shoulder 0.5mm increased to 1mm, under the pressure of the size changes of tensile strength and elongation of the joint is not affected. But in the shoulder press amount increased from 1mm to 1.5mm, the tensile strength and elongation have been significantly improved, the shoulder pressure volume reached the maximum at d=1.5mm, the tensile strength and elongation rates were 213MPa and 6.87%, respectively than d=0.5mm when the friction stir welding increased by 17.7% and 29.4%. (5) in the 7075 Aluminum Alloy butt joint, organization of the nugget zone has completely dynamic recrystallization, the grain is fine equiaxed grains. The grain grain TMAZ of advancing side than the back side long and irregular grain is not uniform. The grain size change and thermal mechanical affected zone favorable heat affected. (6) the results of the second phase particles of 7075 Aluminum Alloy showed: with the increase of shoulder pressure volume, second phase particles distribution in the nugget zone than the base metal thin The second phase particles in the thermo mechanical affected zone will be elongated and coarsened, and the second phase particles in the heat affected zone gradually become more and more.

【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG453.9

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本文編號(hào)：1429654