本文選題：Nb-N微合金化　切入點：貝氏體　出處：《昆明理工大學》2017年碩士論文

【摘要】：鈮微合金化技術是鋼筋獲得綜合力學性能、優(yōu)良抗震性能、經濟安全的一種生產技術。目前,關于鋼中合金元素的配比對組織和變形行為影響的研究報道集中于N-V、Nb-V復合微合金化,而對Nb-N復合微合金化的研究不足。基于此,本文設計了七種不同Nb、N含量的試驗鋼,研究Nb/N的變化對鋼筋組織和變形行為的影響規(guī)律。同時,通過拉伸試驗SEM原位觀察具有不同組織的試驗鋼筋在不同變形量下的組織演變規(guī)律,研究組織對變形行為的作用機理,并進行裂紋萌生與擴展分析。通過對七種不同Nb、N含量的鋼筋的顯微組織及抗震性能進行分析,結果表明,試驗鋼的組織均為鐵素體+珠光體+少量貝氏體。Nb含量的增加抑制珠光體的形成,但能促進貝氏體含量的增加,同時細化組織。N含量的增加有利于屈服強度和抗拉強度的提高,使強屈比增大,抗震性能得到改善。試驗鋼的鈮氮比(Nb/N)為4.29左右時,鋼筋的抗拉強度和屈服強度均達到最大值,且有利于強屈比的提高。鋼筋鈮氮比越接近于理想化學配比值6.63,析出相量越多,且更為細小。擬合得到鐵素體晶粒尺寸與其顯微硬度之間的定量關系式。對具有鐵素體、珠光體和極少量貝氏體的鋼筋的SEM原位拉伸觀察結果表明,鐵素體和珠光體變形明顯,鐵素體優(yōu)先變形,鐵素體變形到一定程度之后引起臨近珠光體內滑移系的開動,最后導致珠光體的斷裂。對具有不同貝氏體含量的試驗鋼筋原位拉伸變形過程的研究結果表明,貝氏體的引入使變形機制發(fā)生變化。貝氏體體積分數(shù)為10%左右時,試驗鋼的強度和塑韌性配合最好,變形以鐵素體和珠光體為主。貝氏體在變形過程中對其它組織有阻礙作用,變形初期僅發(fā)生一定程度的偏轉。變形控制的主因為鐵素體和珠光體的滑移運動、貝氏體的轉動。貝氏體含量超過50%時,試驗鋼中出現(xiàn)大量的針狀鐵素體。變形初期以鐵素體變形為主,珠光體變形不明顯的原因可能是貝氏體作為硬質相對其變形的阻礙作用。貝氏體和鐵素體承擔主要的變形。隨著變形量的增加,珠光體逐漸斷裂,貝氏體沿平行于拉伸軸方向排列,使得變形難以繼續(xù)。對斷裂過程的研究結果表明,顯微裂紋主要萌生于鐵素體/鐵素體晶界、鐵素體/貝氏體和珠光體/貝氏體相界等這些應力集中的地方,并沿晶界或相界處進一步擴展,最終導致斷裂。
[Abstract]:Niobium microalloying technology is a kind of production technology which can obtain comprehensive mechanical properties, excellent aseismic performance and economic safety of steel bars. The study on the effect of alloying element ratio on microstructure and deformation behavior of steel was focused on N-VN Nb-V composite microalloying, but not on Nb-N composite microalloying. Based on this, seven kinds of experimental steels with different NbN content were designed. The effect of the change of Nb/N on the microstructure and deformation behavior of steel bar was studied. At the same time, through the tensile test SEM in situ, the evolution law of the steel bars with different structures was observed, and the mechanism of the effect of the structure on the deformation behavior was studied. By analyzing the microstructure and seismic behavior of seven kinds of steel bars with different NbN content, the results show that, The microstructure of the test steel is that the increase of ferrite pearlite bainite. NB content can inhibit the formation of pearlite, but it can promote the increase of bainite content, at the same time, the increase of microstructure and N content is beneficial to the increase of yield strength and tensile strength. When the NB / N ratio of test steel is about 4.29, the tensile strength and yield strength of steel bar reach the maximum. The ratio of niobium to nitrogen is close to the ideal chemical ratio 6.63, the precipitated phase is more and smaller. The quantitative relation between the grain size of ferrite and its microhardness is obtained by fitting the quantitative relation between ferrite grain size and microhardness. The SEM in-situ tensile observation of pearlite and a very small amount of bainite bars shows that the deformation of ferrite and pearlite is obvious, the deformation of ferrite is preferred, and the deformation of ferrite to a certain extent leads to the start of slip system near pearlite. The results show that the deformation mechanism is changed by the introduction of bainite. When the volume fraction of bainite is about 10%, the deformation mechanism is changed. The strength and ductility of the test steel are the best, and the deformation is mainly ferrite and pearlite. Bainite hinders other microstructure during deformation. Only a certain degree of deflection occurs in the early stage of deformation. The main causes of deformation control are the slip movement of ferrite and pearlite, the rotation of bainite. There are a large number of acicular ferrite in the test steel. The reason why the pearlite deformation is not obvious is that bainite acts as an obstacle to its deformation. Bainite and ferrite bear the main deformation. With the increase of deformation amount, pearlite gradually breaks. The bainite is arranged along the direction parallel to the tensile axis, which makes it difficult to continue the deformation. The results of the fracture process show that the microcracks mainly occur at the grain boundary of ferrite / ferrite. These stress concentration areas such as ferrite / bainite and pearlite / bainite phase boundary extend further along grain boundary or phase boundary and eventually lead to fracture.
【學位授予單位】：昆明理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG142.1

【參考文獻】

相關期刊論文 前10條

1 劉金源;鐘壽軍;;HRB500E屈服強度偏低原因分析[J];江西冶金;2016年01期

2 劉艷林;;HRB500E高強抗震鋼筋的開發(fā)[J];甘肅冶金;2015年03期

3 邵際平;徐玉強;葉爾哈那提;高磊;;提高HRB500E抗震鋼筋強屈比的措施[J];新疆鋼鐵;2015年02期

4 劉國良;郭營利;;采用釩氮合金生產HRB500E實踐[J];甘肅冶金;2015年02期

5 彭沖;唐淑云;王海輪;黃小山;;抗震鋼筋HRB500E的試制[J];江西冶金;2015年01期

6 張偉;;抗震鋼筋HRB500E工藝研究及生產開發(fā)[J];甘肅冶金;2015年01期

7 張靜;;微合金化對高強鋼筋微觀組織和抗震性能的影響[J];鑄造技術;2015年01期

8 周道樹;;釩微合金化HRB500E高強度抗震鋼筋的開發(fā)[J];科技致富向導;2014年18期

9 單忠德;姜超;莊百亮;李新亞;;B1500HS鋼低冷速形變下的力學性能與Hall-Petch關系[J];材料熱處理學報;2014年04期

10 王洪利;李義長;趙如龍;樊毅;李榮華;;VN及VN+Mo復合微合金化HRB500E高強抗震鋼筋生產實踐[J];鋼鐵釩鈦;2014年01期

相關會議論文 前3條

1 牟立君;唐耀武;;500MPa高強度抗震鋼筋的研發(fā)[A];2012年全國軋鋼生產技術會論文集（下）[C];2012年

2 劉清友;候豁然;陳紅桔;董瀚;;Nb、V對超細晶粒鋼組織和力學性能的影響[A];2001中國鋼鐵年會論文集（下卷）[C];2001年

3 Steven G.Jansto;王厚昕;;鈮在高強度抗震鋼筋生產中的應用[A];2009全國建筑鋼筋生產、設計與應用技術交流研討會會議文集[C];2009年

相關碩士學位論文 前4條

1 鐘仲華;高強度抗震鋼筋在不同溫度下的拉伸變形行為研究[D];昆明理工大學;2015年

2 鄧蕾;500MPa高強度抗震鋼筋多相組織在拉伸變形過程中的演變規(guī)律[D];昆明理工大學;2013年

3 劉南;氮對提高20MnSi鋼強度的作用機理研究[D];內蒙古科技大學;2011年

4 馬興云;利用軋后控制冷卻生產高強度帶肋鋼筋的工藝研究與應用[D];山東大學;2006年

，

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