本文選題：鐵素體不銹鋼 + 再結(jié)晶��； 參考：《上海大學(xué)》2016年博士論文

【摘要】：鐵素體不銹鋼由于僅含少量鎳或不含鎳,在鎳資源越來越緊張的今天,正逐步替代奧氏體不銹鋼,在汽車,家電等領(lǐng)域獲得廣泛應(yīng)用,成為一種資源節(jié)約型的綠色環(huán)保不銹鋼材料。但是與奧氏體不銹鋼相比,鐵素體不銹鋼在力學(xué),成形性,耐蝕,抗氧化等方面仍然存在一定的不足。近年來,隨著不銹鋼冶煉技術(shù)和精煉技術(shù)的發(fā)展和應(yīng)用,使得鐵素體不銹鋼中的C,N等有害元素含量大幅降低,超純鐵素體不銹鋼的耐蝕性能獲得有效提高。研究發(fā)現(xiàn),在鋼液凝固過程中,Al不但能促進(jìn)非均勻異質(zhì)形核,提高等軸晶比例,降低板材各向異性,而且還能在熱處理過程中細(xì)化晶粒,提高板材力學(xué)性能。更為重要的是,當(dāng)Al達(dá)到一定含量時(shí),可以在不銹鋼表面形成一層致密的富Al_2O_3氧化膜,大幅提高不銹鋼的抗高溫氧化性能。本文主要研究了合金元素Al對(duì)超純鐵素體不銹鋼的再結(jié)晶行為、成形性能和1000oC等溫氧化行為的影響。通過采用金相顯微鏡、XRD衍射、SEM掃描電鏡、TEM透射電鏡、EBSD背散射衍射及Thermo-Calc熱力學(xué)平衡相圖計(jì)算等技術(shù)手段研究了微觀組織結(jié)構(gòu)的演變規(guī)律。主要結(jié)論如下:1)Al可以顯著降低429超純鐵素體不銹鋼的再結(jié)晶溫度,冷軋退火后的平均晶粒大小隨著Al含量的增加有少量增加,這主要是因?yàn)樵俳Y(jié)晶溫度和夾雜物的面積分?jǐn)?shù)的顯著降低。室溫拉伸抗拉強(qiáng)度和屈服強(qiáng)度隨著Al含量的增加而線性提高,延伸率變化不大,但是塑性應(yīng)變比先增加后減少,含0.16 wt.%Al樣品呈現(xiàn)出最高的塑性應(yīng)變比r=1.62。Al含量的增加可以顯著改善429超純鐵素體不銹鋼的高溫拉伸和壓縮力學(xué)性能。隨著Al含量的提高,基體和晶界夾雜物類型從單相的TiN演變成復(fù)合MgO·Al_2O_3-TiN顆粒,并且夾雜物的平均大小有少量的增加而面積比例分?jǐn)?shù)降低。Al含量的增加可以顯著改善抗點(diǎn)蝕性能。2)冷軋和退火后429超純鐵素體不銹鋼表層和中心層的織構(gòu)從α+γ織構(gòu)演變成完全的γ織構(gòu),并且0.16 wt.%Al的加入提高了(111)[-1-12]和(111)[-2-35]織構(gòu)的強(qiáng)度,但是當(dāng)Al含量進(jìn)一步增加到1.51 wt.%時(shí)γ織構(gòu)強(qiáng)度反而降低了。厚度方向的γ織構(gòu)隨著Al含量的增加,從(111)[1-21]轉(zhuǎn)到(111)[3-52],且0.16 wt.%的Al可以顯著提高γ織構(gòu)的強(qiáng)度。不含Al樣品冷軋退火后γ-織構(gòu)在室溫拉伸后消失了,而含0.16 wt.%Al樣品中γ-織構(gòu)仍然占主導(dǎo),111//ND的最高強(qiáng)度為4.6。含1.51 wt.%Al樣品室溫拉伸后(111)[0-11]織構(gòu)強(qiáng)度顯著降低。含0.16 wt.%Al的429超純鐵素體不銹鋼具有最強(qiáng)γ織構(gòu)。3)429超純鐵素體不銹鋼1000oC氧化增重曲線呈現(xiàn)典型的拋物線規(guī)律。氧化較短時(shí)間后,不含Al樣品呈球狀形貌的局部區(qū)域優(yōu)先氧化,隨著氧化時(shí)間的增加表面氧化膜擴(kuò)展到整個(gè)樣品表面且球狀氧化產(chǎn)物長(zhǎng)到一起,氧化產(chǎn)物頂端存在一些細(xì)小的孔洞。隨著Al含量的增加,表面氧化膜形貌較為均勻,氧化產(chǎn)物呈顆粒狀形貌。氧化膜呈現(xiàn)出多層結(jié)構(gòu),外層氧化膜富含F(xiàn)e_2O_3和少量的Fe_3O_4,外層氧化膜下方有Cr_2O_3,中間層氧化膜富含F(xiàn)e_2O_3和Cr_2O_3,內(nèi)層氧化膜富含F(xiàn)e_3O_4。隨著Al含量的提高,氧化膜厚度減少,低Al含量樣品高溫抗氧化性能的改善主要依靠Cr_2O_3。當(dāng)Al含量增加到1.51 wt.%時(shí),氧化較短時(shí)間后樣品表面出現(xiàn)了富Al_2O_3的氧化膜,隨著氧化時(shí)間的增加,氧化膜厚度增加不顯著。1.51 wt.%Al樣品表層下形成的具有保護(hù)性的、均勻的、完整的、富Al_2O_3的氧化膜,顯著提高429超純鐵素體不銹鋼的高溫抗氧化性能。
[Abstract]:Ferritic stainless steel due to only small amounts of nickel or nickel free, in nickel resources increasingly tense today, is gradually replacing the austenitic stainless steel, widely used in automobiles, household appliances and other fields, become green stainless steel material is a kind of resource saving. But compared with austenitic stainless steel, ferritic stainless steel in mechanics, forming property, corrosion resistance, anti-oxidation and other aspects still exist some shortcomings. In recent years, with the development and application of stainless steel smelting and refining technology, the ferritic stainless steel of C, N and other harmful elements were significantly reduced, the corrosion resistance of ultra pure ferritic stainless steel was effectively improved. The study found that in liquid steel during the solidification process of Al can not only promote the inhomogeneous nucleation, increase the proportion of equiaxed grains, reduce material anisotropy, but also refine the grain in the heat treatment process, improve the mechanical properties of the plate more. It is important that when Al reached a certain level, Al_2O_3 rich oxide film can form a dense layer on the surface of stainless steel, greatly improve the oxidation resistance of stainless steel. This paper mainly studies the alloy element Al on ultra pure ferritic stainless steel recrystallization behavior, forming property and 1000oC isothermal oxidation behavior by means of metallographic. Microscope, XRD diffraction, scanning electron microscopy and transmission electron microscopy SEM, TEM, EBSD technology and Thermo-Calc back scattering diffraction thermodynamic equilibrium phase diagram calculation and research the evolution of the microstructure. The main conclusions are as follows: 1) the recrystallization temperature of Al can significantly reduce the 429 ultra pure ferritic stainless steel, the average grain size with the cold rolling and annealing the increase of the content of Al increased slightly, mainly because of the decreased area fraction of recrystallization temperature and inclusions. The tensile tensile strength and yield strength with With the increase of Al content, linear increase, elongation rate changed little, but the plastic strain ratio increased first and then decreased, containing 0.16 wt.%Al samples exhibited the highest plastic strain ratio of the increase of the content of r=1.62.Al can significantly improve the high temperature tensile 429 ultra pure ferritic stainless steel and compressive mechanical properties. With increasing Al content. The type of inclusion matrix and grain boundary evolution from single-phase TiN into composite MgO Al_2O_3-TiN particles, and the average size of the inclusions have a small amount of increased area percentage decreased the content of.Al can significantly improve the pitting corrosion resistance of.2 cold rolling and annealing textures) 429 ultra pure ferritic stainless steel surface and the center layer from the alpha + gamma texture texture completely evolved into gamma, and 0.16 wt.%Al were higher (111) and [-1-12] (111) [-2-35] texture intensity, but when the Al content increases further to 1.51 wt.% gamma texture intensity While reducing the thickness direction of the gamma texture. With the increase of Al content, from (111) to [1-21] (111) [3-52], and 0.16 wt.% Al can significantly improve the gamma texture intensity. Al free samples of cold rolled and annealed after gamma texture in tensile and disappeared, while the samples containing 0.16 wt.%Al gamma the texture still dominates, the highest intensity of 111//ND 4.6. containing 1.51 wt.%Al samples (111) after room temperature tensile strength of [0-11] texture decreased significantly. 429 ultra pure ferritic stainless steel containing 0.16 wt.%Al has the strongest gamma texture.3) 429 ultra pure ferritic stainless steel 1000oC oxidation weight curve exhibits a typical parabolic law. The oxidation of short time after excluding Al samples showed local preferential oxidation of spherical appearance, with the increase of oxidation time of surface oxide film is extended to the entire surface of the sample and the spherical oxidation products grown together, the top hole oxidation products exist some small Al with. With the increase of the content of oxide film on the surface, more uniform morphology, granular morphology of oxide film. The oxidation product presents a multi-layer structure, the outer film is rich in Fe_2O_3 and a small amount of Fe_3O_4, the outer film below Cr_2O_3, middle layer rich in Fe_2O_3 and Cr_2O_3, the inner oxide film is rich in Fe_3O_4. with the increase of Al content, reduce the thickness of the oxide film, low Al content high temperature oxidation samples to improve the performance of Cr_2O_3. mainly depends on when the content of Al increased to 1.51 wt.%, the oxidation of a short time after the emergence of the Al_2O_3 rich oxide film sample surface, with the increase of oxidation time, the thickness of the oxide film did not significantly increase.1.51 wt.%Al sample surface formed under protective, uniform, full, rich Al_2O_3 the film, significantly improve the oxidation resistance of 429 ultra pure ferritic stainless steel.

【學(xué)位授予單位】：上海大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TG142.71

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 顧金磊;余海峰;顧佳卿;江來珠;金學(xué)軍;;冷軋工藝對(duì)00Cr21MoNbTi鐵素體不銹鋼組織、織構(gòu)與成形性能的影響[J];鋼鐵;2011年04期

2 杜偉;江來珠;孫全社;劉振宇;;冷軋壓下率對(duì)鐵素體不銹鋼深沖性能的影響[J];材料熱處理學(xué)報(bào);2010年08期

，

本文編號(hào)：1736902