本文選題：軸承鋼 + 網狀碳化物��； 參考：《北京科技大學》2015年博士論文

【摘要】：隨著我國盾構施工領域的快速發(fā)展,盾構機的生產和制造行業(yè)迅速發(fā)展。但是,由于我國高品質軸承鋼材料的生產技術落后,盾構機的核心部件——主軸軸承還未能實現國產化,而是100%采用了進口產品,這大大增加了盾構機的生產成本,嚴重制約了我國大型盾構機行業(yè)的進一步發(fā)展。本文以軸承鋼GCr1SSiMn為研究對象,開展了6米以上直徑的大型盾構機主軸承滾動體材料的組織演變機理和性能控制研究,實現了國內大型盾構機用軸承滾動體材料質量控制的新突破,為大型盾構機軸承滾動體制造的國產化提供了材料保障；以軸承鋼GCr15為研究對象,系統(tǒng)開展高碳鉻軸承鋼的Nb微合金化研究,闡述Nb對高碳鉻軸承鋼顯微組織的影響規(guī)律和作用機理。 對軸承鋼GCr15SiMn的熱變形行為和晶粒長大行為進行了研究。確立了變形溫度和變形量與動態(tài)再結晶狀態(tài)的關系,為軸承鋼生產過程中的軋制工藝設計提供了理論基礎；利用動態(tài)再結晶的動力學模型,實現了對軸承鋼GCr15SiMn動態(tài)再結晶體積分數的準確預測；確定了加熱溫度和保溫時間與奧氏體晶粒尺寸的定量關系,并建立奧氏體晶粒長大動力學模型,實現了對軸承鋼GCr15SiMn奧氏體晶粒尺寸的準確預測。 研究了變形量、變形溫度和冷卻速度與網狀碳化物狀態(tài)的變化規(guī)律。明確了控制軸承鋼GCr15SiMn網狀碳化物的臨界冷卻條件；通過研究共析轉變過程中網狀碳化物的析出規(guī)律,闡述了軋后冷卻過程中網狀碳化物的析出機理以及控制策略。確定當精軋累積變形量為50%-60%,終軋溫度為850-900℃,軋后以大于3℃/s的冷卻速度冷卻到620℃等溫相變時,可以有效地抑制二次網狀碳化物的形成與析出,獲得具有良好索氏體組織狀態(tài)的軋材。 通過對大斷面軸承鋼GCr15SiMn熱處理過程中碳化物遺傳性及演變機理的研究,提出了軋材網狀碳化物厚度與最終熱處理產品網狀碳化物級別的定量關系,確定了可以經熱處理完全消除的臨界網狀碳化物尺寸為0.29μm,為控制軋材產品中的網狀碳化物狀態(tài)提供了新的思路和方法。 系統(tǒng)研究了大斷面軸承滾動體材料GCr15SiMn的強韌化機制,獲得了硬度、強度和韌性具有良好的匹配高品質軸承鋼材料,實現了國內大型盾構機用高品質軸承鋼滾動體材料質量控制的新突破。確定了大斷面軸承鋼GCr15SiMn的最佳熱處理工藝為：815～830℃淬火,淬火保溫1h,165-180℃回火,回火4-6h；明確了最佳顯微組織,即細小板條束的馬氏體基體上分布著均勻、細小的顆粒狀碳化物,馬氏體板條間分布厚度約為20nm的薄膜狀殘余奧氏體,體積分數在12.8%～17.7%之間。 通過在軸承鋼GCr15中添加了不同含量(0%,0.018%和0.040%)的Nb元素,系統(tǒng)開展了高碳鉻軸承鋼的Nb微合金化研究。闡明了隨著Nb含量增加,網狀碳化物厚度和碳化物網尺寸減小,珠光體片層間距變薄的規(guī)律；提出了Nb促進軸承鋼球化退火的兩個機制,即未溶碳化物核心增多和奧氏體中C濃度的不均勻增大；揭示了Nb在高碳鉻軸承鋼碳化物演變過程中的作用機理。
[Abstract]:With the rapid development of the field of shield construction in China, the production and manufacturing industry of the shield machine has developed rapidly. However, because of the backward production technology of high quality bearing steel materials in our country, the core component of the shield machine, the spindle bearing, has not been made domestically, but 100% of the imported products have been adopted, which greatly increases the production cost of the shield machine. This paper seriously restricts the further development of large shield machine industry in China. This paper, taking bearing steel GCr1SSiMn as the research object, carried out the research on the mechanism and performance control of the material of the main bearing rolling body of large shield machine with 6 meters in diameter, and realized a new breakthrough in the quality control of the large shield machine. The localization of the bearing roller of type shield machine provides material support. Taking the bearing steel GCr15 as the research object, the study of Nb microalloying of high carbon chromium bearing steel is carried out systematically, and the influence rule and action mechanism of Nb on the microstructure of high carbon chromium bearing steel are expounded.
The thermal deformation behavior and grain growth behavior of bearing steel GCr15SiMn were studied. The relationship between the deformation temperature and the deformation amount and the dynamic recrystallization state was established, which provided the theoretical basis for the rolling process design in the bearing steel production process, and the dynamic re junction of the bearing steel GCr15SiMn was realized by dynamic recrystallization dynamic model. The accurate prediction of the crystal volume fraction, the quantitative relation between the heating temperature and the holding time and the austenite grain size was determined, and the dynamic model of austenite grain growth was established, and the accurate prediction of the grain size of the bearing steel GCr15SiMn austenite was realized.
The changing laws of deformation, deformation temperature, cooling rate and network carbide state are studied. The critical cooling conditions for controlling GCr15SiMn network carbide in bearing steel are clarified, and the precipitation mechanism of net carbide in the process of cooling and control strategy in the process of cooling process is expounded. It is determined that the formation and precipitation of two reticulate carbide can be effectively suppressed when the cumulative deformation of the finishing rolling is 50%-60%, the final rolling temperature is 850-900 C, and the cooling rate of 3 degrees centigrade is more than 3 C, and the rolling material with good Soxhlet structure can be obtained.
Through the study of the carbides heredity and evolution mechanism during the heat treatment process of large section bearing steel GCr15SiMn, the quantitative relationship between the thickness of the mesh carbide and the net carbide level of the final heat treatment product was put forward. The critical mesh size of the reticular carbides, which can be completely eliminated by heat treatment, was determined to be 0.29 mu m, which was used to control the rolled products. The network carbide state provides new ideas and methods.
The strong and toughening mechanism of the rolling material GCr15SiMn of large section bearing is studied systematically. The hardness, strength and toughness are well matched with high quality bearing steel material. The new breakthrough in quality control of the high quality bearing steel roller material used in large shield machine is realized. The best heat treatment worker of large section bearing steel GCr15SiMn is determined. The art is: quenching at 815~830 C, quenching and holding heat for 1h, tempering at 165-180 C and tempering 4-6h, it is clear that the best microstructure, that is, the martensitic matrix of the martensitic matrix of the thin strip beam is distributed evenly, fine granular carbides, and the thin film like retained austenite with a thickness of about 20nm between martensitic plates, and the volume fraction is between 12.8% and 17.7%.
By adding Nb elements with different content (0%, 0.018% and 0.040%) in the bearing steel GCr15, the study of Nb microalloying of high carbon chromium bearing steel was carried out systematically. The law of the thickness of network carbide and the size of carbide net decreased with the increase of Nb content, and the two of Nb to promote the spheroidization of bearing steel by Nb was put forward. The mechanism, that is, the increase of the undissolved carbide core and the inhomogeneous increase of the C concentration in the austenite, reveals the mechanism of Nb in the evolution of carbides in high carbon chromium bearing steel.
【學位授予單位】：北京科技大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TG142.1

【參考文獻】

相關期刊論文 前10條

1 郭守真;楊王s，

本文編號：1953874