本文選題：氧化物彌散強(qiáng)化 + 鐵素體鋼　； 參考：《北京科技大學(xué)》2016年博士論文

【摘要】：目前為止,人類面臨的最大問題就是日趨增長(zhǎng)的能源需求問題,對(duì)這一問題的解決需要綜合考慮新能源的開發(fā)利用以及環(huán)境污染等諸多因素。在新能源中,核裂變能(Fission Energy)很可能在未來的低碳環(huán)保能源系統(tǒng)中繼續(xù)扮演非常重要的角色。根據(jù)國(guó)家政策要求,當(dāng)今核裂變反應(yīng)堆需要朝著更高效以及服役壽命更長(zhǎng)的方向發(fā)展。由于超臨界水堆(Supercritical Water Reactor, SCWR)具有很高的經(jīng)濟(jì)性、優(yōu)異的熱效率、以及簡(jiǎn)單的設(shè)計(jì)理念,因此成為了第四代先進(jìn)核裂變系統(tǒng)中的重要候選堆型之一。由于超臨界水堆需要在強(qiáng)中子輻照、高瞬變應(yīng)力、以及強(qiáng)腐蝕性介質(zhì)這樣極端的環(huán)境下運(yùn)行,因此,材料問題成為制約其工程應(yīng)用的一個(gè)關(guān)鍵性問題。因?yàn)榧{米氧化物彌散強(qiáng)化(Oxide Dispersion Strengthened, ODS)鐵素體鋼(Ferritic Steels)具有優(yōu)異的抗輻照損傷性能、高溫力學(xué)性能、以及抗腐蝕潛力,被認(rèn)為是超臨界水堆包殼管的主要候選材料之一。ODS鐵素體鋼具有如此優(yōu)異的性能主要是源自于它特殊的顯微組織結(jié)構(gòu)。通常情況下,ODS鐵素體鋼內(nèi)部存在著大量尺寸極為細(xì)小的納米氧化物彌散粒子,它們可以作為釘扎質(zhì)點(diǎn)有效地阻止基體內(nèi)位錯(cuò)和晶界的移動(dòng),從而提高材料的力學(xué)性能以及熱穩(wěn)定性能。同時(shí),這些納米氧化物彌散粒子還可以作為穩(wěn)定的“池子”對(duì)輻照后的ODS鐵素體鋼中產(chǎn)生的缺陷進(jìn)行捕獲和釘扎,從而提高材料的抗輻照性能。眾所周知,Cr含量對(duì)ODS鐵素體鋼的性能起著重要的作用。一般而言,由于低Cr含量的ODS鐵素體鋼的抗腐蝕性能不夠優(yōu)異,這使得它們?cè)诔R界水堆中的應(yīng)用受到一定限制。然而,如果ODS鐵素體鋼中的Cr含量過高,長(zhǎng)時(shí)間服役之后基體內(nèi)部可能會(huì)產(chǎn)生大量的富Cr相從而引起材料的時(shí)效脆化。因此,通過實(shí)驗(yàn)研究找到一個(gè)合適的Cr含量值對(duì)于服役于超臨界水堆中的ODS鐵素體鋼是至關(guān)重要的。在本研究中,通過機(jī)械合金化和熱等靜壓的方法制備了Cr含量分別為12%、14%、16%、以及18%(質(zhì)量分?jǐn)?shù))的四種ODS鐵素體鋼樣品。采用熱加工(鍛造／軋制)的方法提高燒結(jié)后材料的力學(xué)性能,再通過熱處理工藝消除熱加工給材料帶來的殘余應(yīng)力。采用光學(xué)顯微鏡(Optical Microscope, OM)、掃描電子顯微鏡(Scanning Electron Microscopy, SEM)、以及透射電子顯微鏡(Transmission Electron Microscopy, TEM)等先進(jìn)表征手段對(duì)不同Cr含量的ODS鐵素體鋼樣品的顯微組織結(jié)構(gòu)進(jìn)行了系統(tǒng)地研究。結(jié)果表明不同Cr含量的ODS鐵素體鋼的晶粒尺寸都呈現(xiàn)出一種雙峰分布的特征。所有樣品的基體中都可以觀察到大量均勻分布的Y-Ti-O型的納米氧化物彌散粒子,這些彌散粒子的尺寸幾乎都在幾個(gè)納米至五十個(gè)納米之間。對(duì)不同Cr含量ODS鐵素體鋼樣品的維氏顯微硬度、拉伸性能、沖擊韌性等力學(xué)性能進(jìn)行測(cè)試,分析結(jié)果表明Cr含量的變化對(duì)于ODS鐵素體鋼的力學(xué)性能的影響并不是非常明顯。此外,我們對(duì)不同Cr含量的ODS鐵素體鋼的其它服役性能也進(jìn)行了測(cè)試和對(duì)比,包括材料在600℃/25 MPa條件下抵抗超臨界水介質(zhì)腐蝕的性能,材料在700℃的長(zhǎng)期時(shí)效穩(wěn)定性,以及材料在500℃條件下進(jìn)行雙束離子輻照(1 MeV Kr+ and 15 keV He+)后的顯微組織變化等。最終,根據(jù)結(jié)果對(duì)比優(yōu)選出綜合性能較為優(yōu)異的Cr含量為16%的ODS鐵素體鋼作為未來研究和生產(chǎn)的主要材料。在本次研究中除了制備了不同Cr含量的ODS鐵素體鋼樣品之外,我們還嘗試通過機(jī)械合金化(MA)和熱擠壓(Hot Extrusion, HE)的方法制備了一種可以適用于超臨界水堆以及超高溫反應(yīng)堆(Very High Temperature Reactor, VHTR)的新型Hastelloy XR-ODS鎳基合金。相比傳統(tǒng)的Hastelloy XR型鎳基合金而言,經(jīng)過納米氧化物彌散強(qiáng)化之后的Hastelloy XR-ODS鎳基合金在強(qiáng)度方面得到了明顯的提高,但是其塑性卻發(fā)生了嚴(yán)重地下降。通過裝備有能譜分析儀(X-ray Energy Dispersive Spectroscopy, EDS)的高分辨透射電子顯微鏡(High-Resolution Transmission Electron Microscopy, HRTEM)結(jié)合選區(qū)電子衍射分析技術(shù)(Selected Area Electronic Diffraction, SAD)對(duì)Hastelloy XR-ODS鎳基合金樣品的顯微組織結(jié)構(gòu)進(jìn)行系統(tǒng)地研究,根據(jù)實(shí)驗(yàn)分析結(jié)果發(fā)現(xiàn)造成材料塑性不佳的主要原因是其內(nèi)部存在著大量的尺寸在微米級(jí)的晶界第二相析出物、相連化合物、以及非晶態(tài)二氧化硅。
[Abstract]:So far, the biggest problem facing mankind is the growing energy demand problem. The solution of this problem requires a comprehensive consideration of the development and utilization of new energy and environmental pollution. In the new energy, nuclear fission energy (Fission Energy) is very likely to continue to play a very important role in the future low carbon environmental energy system. Role. According to national policy, nuclear fission reactors need to develop in the direction of more efficient and longer service life. Because the Supercritical Water Reactor (SCWR) has high economic, excellent thermal efficiency and simple design concepts, it has become the weight of the fourth generation of advanced nuclear fission systems. One of the candidate reactor types. Because the supercritical water reactor needs to be operated in extreme conditions such as strong neutron irradiation, high transient stress, and strong corrosive medium, the material problem becomes a key problem that restricts its engineering applications. Because of the nano oxide dispersion strengthening (Oxide Dispersion Strengthened, ODS) ferrite steel (Ferriti C Steels) has excellent resistance to radiation damage, high temperature mechanical properties and corrosion resistance. It is considered to be one of the main candidate materials for the supercritical water reactor shell tube,.ODS ferrite steel has such excellent properties mainly from its special microstructure. Under ordinary conditions, there are a large number of rulers inside the ODS ferrite steel. The nanometer oxide dispersion particles are very small, which can effectively prevent the dislocation and grain boundary movement in the matrix as the pinning particles, thus improving the mechanical properties and thermal stability of the materials. At the same time, these nano oxide dispersion particles can also be used as stable "pool" to produce the irradiated ODS ferrite steel. It is well known that the Cr content plays an important role in the performance of the ODS ferrite steel. Generally speaking, the low Cr content of the ODS ferrite steel is not excellent in corrosion resistance, which makes their application in the supercritical water reactor limited. However, if ODS iron is used. The content of Cr in the plain body steel is too high. After a long time service, a large number of rich Cr phases may be produced in the matrix and thus cause the aging embrittlement of the material. Therefore, it is necessary to find a suitable value of the Cr content for the ODS ferrite steel in the supercritical water reactor. Four kinds of ODS ferritic steel samples with Cr content of 12%, 14%, 16%, and 18% (mass fraction) were prepared by isostatic pressure. The mechanical properties of the sintered materials were improved by hot working (forging / rolling), and the residual stresses produced by heat processing were eliminated by heat treatment. The optical microscope (Optical Microscope) was used. OM), scanning electron microscopy (Scanning Electron Microscopy, SEM), and transmission electron microscopy (Transmission Electron Microscopy, TEM) have been used to systematically study the microstructure of ODS ferrite steel samples with different Cr content. The results show that the grain size of the ferrite steel with different Cr content is all. A large number of uniformly distributed Y-Ti-O type nano oxide dispersion particles can be observed in the matrix of all samples. The size of these dispersion particles is almost between a few nanometers and fifty nanometers. The microhardness, tensile properties and impact toughness of the Vivtorinox with different Cr content of ODS ferrite steel samples are made. The mechanical properties of the ODS ferrite steel are not obviously affected by the change of Cr content. In addition, we also test and compare the other service properties of the ODS ferrite steel with different Cr content, including the resistance to the supercritical water medium corrosion under the condition of /25 MPa at 600. The properties, the long-term stability of the material at 700 C, and the microstructure change of the material at 500 C under the condition of double beam irradiation (1 MeV Kr+ and 15 keV He+). Finally, according to the results, the ODS ferrite steel with a better Cr content of 16% is selected as the main material for future research and production. In addition to the preparation of ODS ferrite samples with different Cr content, we have also tried to prepare a new type of Hastelloy nickel base alloy which can be applied to the supercritical water reactor and the ultra high temperature reactor (Very High Temperature Reactor, VHTR) by mechanical alloying (MA) and hot extrusion (Hot Extrusion, HE). Compared with the traditional Hastelloy XR nickel based alloy, the Hastelloy XR-ODS nickel base alloy after the nano oxide dispersion strengthening has been obviously improved in strength, but its plasticity has been severely reduced. The high resolution transmission electron with the energy spectrum analyzer (X-ray Energy Dispersive Spectroscopy, EDS) is equipped. High-Resolution Transmission Electron Microscopy (HRTEM) combined with electoral electron diffraction analysis (Selected Area Electronic Diffraction, SAD) to systematically study the microstructure of Hastelloy XR-ODS nickel base alloy samples. According to the results of the experimental analysis, the main reasons for the poor plasticity of the materials are found. There are a large number of micron sized grain boundaries, second phase precipitates, connected compounds and amorphous silicon.
【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TG142.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

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本文編號(hào)：2074934