本文選題：800H鎳基耐蝕合金 + La�。� 參考：《太原理工大學(xué)》2017年碩士論文

【摘要】：隨著科學(xué)技術(shù)及工業(yè)生產(chǎn)的快速發(fā)展,800H鎳基耐蝕合金在航空航天、石油化工、核工業(yè)等領(lǐng)域的應(yīng)用越來越廣泛。傳統(tǒng)的800H鎳基合金的生產(chǎn)工藝為模鑄、電渣重熔等,但這種工藝成材率和生產(chǎn)效率低下,成本較高。采用立式板坯連鑄新工藝可大規(guī)模生產(chǎn)800H合金,提高生產(chǎn)效率,但生產(chǎn)的連鑄坯初始凝固組織晶粒粗大,惡化合金的強(qiáng)/韌性。為此,本研究以寶鋼生產(chǎn)的800H鎳基合金為研究對(duì)象,用真空感應(yīng)爐冶煉四組不同La含量的800H試驗(yàn)合金。研究、分析La含量對(duì)凝固組織細(xì)化、夾雜物特征、力學(xué)性能的影響及其作用機(jī)理。為細(xì)化800H合金連鑄坯凝固組織晶,開發(fā)低成本的800H合金生產(chǎn)技術(shù)提供基礎(chǔ)實(shí)驗(yàn)數(shù)據(jù),對(duì)解決生產(chǎn)過程中存在的表面缺陷和廢品率較高的問題,調(diào)整我國(guó)鋼鐵產(chǎn)業(yè)結(jié)構(gòu),具有潛在的應(yīng)用價(jià)值和指導(dǎo)意義。其研究方法和內(nèi)容包括:(1)用真空感應(yīng)爐在MgO坩堝內(nèi)冶煉制備四組不同La含量的800H合金試樣,進(jìn)行化學(xué)成分檢測(cè),結(jié)合現(xiàn)代冶金理論,分析、探討La元素對(duì)鋼液潔凈化、細(xì)晶化的作用機(jī)理;(2)用現(xiàn)代的檢測(cè)技術(shù)手段,如金相顯微鏡(OM)、掃描電鏡(SEM)、能譜儀(EDS),表征實(shí)驗(yàn)數(shù)據(jù),通過熱力學(xué)計(jì)算與動(dòng)力學(xué)分析,描述亞微米級(jí)夾雜物在鋼液精煉過程中的演變機(jī)制;(3)用二維晶格錯(cuò)配度公式,計(jì)算不同夾雜物與800h合金的晶格錯(cuò)配度,定性描述含la亞微米級(jí)夾雜物細(xì)化凝固組織的機(jī)理;(4)用800h合金試樣的力學(xué)性能隨la含量變化的實(shí)驗(yàn)數(shù)據(jù),分析、探討亞微米級(jí)夾雜物對(duì)800h鎳基合金綜合力學(xué)性能的作用機(jī)理。通過試驗(yàn)研究,本文得出以下結(jié)論:(1)800h合金中[la]由0%增加到0.047%時(shí),[o]由0.013%降低到0.007%,[s]由0.003%降低到0.001%,說明la具有很強(qiáng)的脫硫、脫氧和鋼液凈化能力。(2)la可顯著細(xì)化800h合金的凝固組織,當(dāng)[la]由0增加到0.047%時(shí),等軸晶比例由0增加到75%,等軸晶晶粒尺寸由6.0μm減小到3.2μm,枝晶組織變細(xì)變短,一次枝晶間距由77.5μm降低到43.8μm,二次枝晶間距基本沒變。(3)la可以顯著細(xì)化800h合金的奧氏體晶粒,當(dāng)合金中[la]含量由0增加到0.047%時(shí),奧氏體晶粒尺寸由121.32μm變?yōu)?2.57μm。(4)800h合金中添加la后,大尺寸的al2o3夾雜物與長(zhǎng)條狀、大體積的mns夾雜物被改性為小尺寸、類球狀的含la夾雜物,并生成大量高熔點(diǎn)的la2o3和la2o2s顆粒。錯(cuò)配度結(jié)果表明,800h合金(111)面/la2o3的(0001)面之間的錯(cuò)配度為6.7%,800h合金的(100)面/la2o2s的(0001)面之間的錯(cuò)配度為5.42%,因其錯(cuò)配度較低,能夠提供大量的非均質(zhì)形核有效核心,是細(xì)化800h鎳基耐蝕合金合金的凝固組織得到顯著細(xì)化。(5)隨著800h合金中l(wèi)a含量的增加,800h合金的力學(xué)性能呈現(xiàn)明顯升高的趨勢(shì),當(dāng)[la]含量由0增加到0.047%時(shí),試樣的屈服強(qiáng)度、抗拉強(qiáng)度、延伸率、和沖擊功分別提高46.9%、22.3%、21.1%和23%。La改善800H合金的凝固組織,細(xì)化奧氏體晶粒及La對(duì)夾雜物的改性是提高800H合金力學(xué)性能的主要原因
[Abstract]:With the rapid development of science and technology and industrial production, 800H nickel base corrosion resistant alloys are widely used in aerospace, petrochemical, nuclear industry and other fields. The traditional production process of 800H nickel-base alloy is mold casting, electroslag remelting, etc. However, the production efficiency and efficiency of this process are low and the cost is high. The new process of vertical slab continuous casting can produce 800H alloy in large scale and improve the production efficiency. However, the grain size of the initial solidification of the continuous casting billet is coarse, and the strength / toughness of the alloy is deteriorated. Therefore, the 800H nickel-base alloy produced by Baosteel was used to smelt four groups of 800H alloys with different La content in vacuum induction furnace. The effect of La content on solidification microstructure, inclusions, mechanical properties and its mechanism were studied and analyzed. In order to refine solidified microstructure of 800H alloy continuous casting billet and develop low cost 800H alloy production technology, the basic experimental data can be provided to solve the problems of surface defects and high scrap rate in the production process and to adjust the structure of China's iron and steel industry. It has potential application value and guiding significance. The research methods and contents include: using vacuum induction furnace to smelt in MgO crucible four groups of samples of 800H alloy with different La content were prepared. The chemical composition of 800H alloy samples was tested. Combined with modern metallurgical theory, the purification of molten steel by La element was discussed. The mechanism of fine crystallization is characterized by modern detection techniques, such as metallographic microscope, scanning electron microscope (SEM), energy spectrometer (EDS), and thermodynamic calculation and kinetic analysis. The evolution mechanism of submicron inclusions in the refining process of molten steel is described. The lattice mismatch between different inclusions and 800h alloys is calculated by using the two-dimensional lattice mismatch formula. Qualitative description of the mechanism of refining solidified microstructure containing la submicron inclusions) with the experimental data of the change of mechanical properties of 800h alloy samples with la content, the mechanism of the effect of submicron inclusions on the comprehensive mechanical properties of 800h nickel-based alloys is discussed. Through experimental study, the following conclusions are drawn: when [la] increases from 0% to 0.047%, [o] decreases from 0.013% to 0.007% and [s] from 0.003% to 0.001. It shows that la has strong desulfurization, deoxidation and purification ability of molten steel. When [la] increases from 0 to 0.047, the proportion of equiaxed grains increases from 0 to 75, the grain size of equiaxed grains decreases from 6.0 渭 m to 3.2 渭 m, and the dendrite structure becomes thinner and shorter. The primary dendritic spacing was reduced from 77.5 渭 m to 43.8 渭 m, and the secondary dendrite spacing was basically unchanged. The austenitic grain size of 800h alloy could be significantly refined when the content of [la] in the alloy increased from 0 to 0.0477.The austenite grain size changed from 121.32 渭 m to 42.57 渭 m / 4800h alloy. Large size al2o3 inclusions and long stripe, large volume mns inclusions were modified into small size, globular inclusions containing la, and a large number of la2o3 and la2o2s particles with high melting point were formed. The mismatch results show that the mismatch between the / / la2o3 / la0001) faces of the alloy / la2o3 has a mismatch of 5.42) between the / / /'/ /'/\% /\% /\%\%\%\%\%\%\%\%\%\%\%\%\%\%\%\% of the mismatch of the alloy / / /\%\%\% la2o3 /\%\%\%\%\%\%\%\%\ It was found that the solidification microstructure of 800 h nickel base corrosion resistant alloy was significantly refined. (5) with the increase of la content in 800 h alloy, the mechanical properties of the alloy increased obviously. When the content of [la] increased from 0 to 0.047, the yield strength of the specimen was increased. Tensile strength, elongation and impact work were increased by 46.9% and 22.1%, respectively, and 23%.La was used to improve solidification microstructure of 800H alloy. Refinement of austenite grain and modification of inclusion by La were the main reasons for improving mechanical properties of 800H alloy.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG133.4

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