發(fā)布時間：2018-03-30 17:18

  本文選題：30CrMnSiNi2A　切入點：DEFORM-HT　出處：《吉林大學》2017年碩士論文

【摘要】：30CrMnSiNi2A鋼在我國工業(yè)生產的很多領域都有大量應用,除了強度性能非常突出之外其綜合性能也很優(yōu)異。30CrMnSiNi2A鋼屬于低合金超高強度鋼,它是在改進中碳調質鋼30CrMnSiA的過程中發(fā)展而來,合金元素的加入使得30CrMnSiNi2A鋼的淬透性能良好,即使在油淬時其淬透性截面直徑也超過了50mm。30CrMnSiNi2A鋼在航空工業(yè)中用途廣泛,可用于生產飛機起落架、機翼、航空發(fā)動機殼體以及高扭短軸類受力零部件等。為了提高該鋼的強硬度、塑韌性以及抗疲勞等力學性能就需要對其進行熱處理。采用傳統方式探究適合材料的熱處理工藝參數往往需要進行大量的試驗,工作強度很大。此外由于檢測設備的限制,傳統的熱處理工藝很難準確掌握熱處理過程中材料內部相的變化情況而計算機技術的快速發(fā)展以及相變理論的逐步完善為熱處理過程數值模擬技術的出現奠定了基礎,它也為熱處理技術走向精確化、可預測的道路提供了幫助。在熱處理過程中溫度以及冷卻速度對材料的性能起著決定性作用。為了探究適合于30CrMnSiNi2A鋼的熱處理溫度,本文利用DEFORM-HT軟件模擬了30CrMnSiNi2A鋼拉伸試樣在890℃淬火后分別在200℃、250℃以及300℃下回火的熱處理過程。對模擬結果進行分析后發(fā)現,當回火溫度為200℃時,試樣內部的馬氏體基本不發(fā)生變化,試樣整體的強硬度較高而塑韌性較低;當回火溫度升高至250℃時,試樣內部馬氏體分解明顯,回火馬氏體含量增加�；鼗饻囟壬�高到300℃后試樣的強硬度有了明顯下降而塑韌性得到了很大地改善,它的綜合力學性能更加優(yōu)異。為了檢驗模擬結果的準確性,在實驗中對30CrMnSiNi2A鋼拉伸試樣進行了890℃淬火,隨后在200℃、250℃和300℃下進行了回火處理。利用電子拉伸試驗機以及金相顯微鏡等儀器對試樣的力學性能和不同狀態(tài)下的金相組織進行了測試和觀察。此外為了研究不同回火溫度下拉伸試樣的斷裂形式和斷裂機理,本文還利用掃描電鏡觀察了三種試樣的斷口微觀形貌。結果表明,淬火后30CrMnSiNi2A鋼拉伸試樣內部生成了大量的板條馬氏體,硬度顯著升高。試樣回火后產生了回火馬氏體并且在200℃,250℃和300℃下的回火馬氏體形態(tài)變化不大而硬度逐漸降低,這與回火過程中碳化物的析出以及內應力的釋放密切相關。利用掃描電鏡觀察到經過200℃及250℃回火的試樣斷口分別出現了“冰糖狀花樣”以及“河流花樣”,由此可以判斷這兩種試樣的斷裂方式屬于脆性斷裂,而經過300℃回火后的試樣斷口則出現了大量韌窩,這種斷裂方式屬于韌性斷裂。因此對于30CrMnSiNi2A鋼適宜采用淬火加低溫回火的熱處理工藝(例如300℃),這樣可以保證它在保持高強度的同時具有一定的塑韌性,進而獲得較好的綜合力學性能。
[Abstract]:30CrMnSiNi2A steel has a large number of applications in many fields of industrial production in China. In addition to its outstanding strength properties, its comprehensive properties are also excellent. 30CrMnSiNi2A steel belongs to low-alloy ultra-high strength steel. It is developed in the process of improving the medium carbon quenched and tempered steel 30CrMnSiA.The addition of alloy elements makes the hardenability of 30CrMnSiNi2A steel good, and even when quenched in oil, its hardenability cross-section diameter exceeds that of 50mm.30CrMnSiNi2A steel, which is widely used in aviation industry and can be used to produce aircraft landing gear and wing.Aero-engine housing and high-torsion short-shaft bearing parts and so on.In order to improve the toughness, toughness and fatigue resistance of the steel, heat treatment is needed.It is necessary to carry out a lot of experiments and work intension to explore the heat treatment process parameters of suitable materials in traditional way.In addition, due to the limitations of testing equipment,The traditional heat treatment process is very difficult to accurately grasp the change of internal phase in the heat treatment process. The rapid development of computer technology and the gradual improvement of phase transition theory have laid the foundation for the appearance of numerical simulation technology in heat treatment process.It also helps heat treatment technology to move to a precise, predictable path.Temperature and cooling rate play a decisive role in the heat treatment process.In order to investigate the suitable heat treatment temperature for 30CrMnSiNi2A steel, the heat treatment process of tensile specimens of 30CrMnSiNi2A steel after quenching at 890 鈩，

本文編號：1686864