【摘要】：隨著工業(yè)的發(fā)展,特別是汽車制造業(yè)的發(fā)展,冷軋鋼板的需求量得到迅速地增長,因為冷軋鋼板具備功能性高、生產(chǎn)原材料豐富、生產(chǎn)成本相對較低和可批量生產(chǎn)等特點,決定了其短時間內(nèi)的難以替代性。隨著用戶對鋼材性能的要求越來越高,使得改善鋼材的力學性能和性能預測成為了研究熱點,而熱處理作為改善鋼材組織和性能最常用的一種方法,為了能獲得更適合于各個用途性能的鋼鐵材料,對其深入研究是必要的。本文以ST52-3G鋼冷軋板為研究對象,以Gleeble-1500D為研究手段,根據(jù)用戶對冷軋鋼板的力學性能要求,研究不同等溫熱處理溫度和保溫時間下其組織演變規(guī)律,特別是鐵素體的再結晶規(guī)律,以及預測不同等溫熱處理溫度和保溫時間下的力學性能,為實際生產(chǎn)制定熱處理工藝提供參考。本論文的主要內(nèi)容包括如下:ST52-3G鋼過冷奧氏體連續(xù)冷卻相轉(zhuǎn)變曲線的測定(Continuous Cooling Transformation—CCT)。用Gleeble-1500D熱模擬試驗機的膨脹儀測得膨脹曲線,用切線法測得Ac1、Ac3及相轉(zhuǎn)變點,并結合金相-硬度法,得到ST52-3G鋼的CCT曲線,同時還做了50℃/s快速加熱下的Ac1、Ac3,快速加熱的臨界轉(zhuǎn)變點比標準條件的提高顯著。等溫熱處理試驗。等溫熱處理工藝主要研究不同加熱溫度和保溫時間下的組織演變規(guī)律,結果表明:ST52-3G鋼在等溫熱處理過程中,加熱溫度在500℃~550℃區(qū)間,其微觀組織僅發(fā)生了回復,在650℃~850℃區(qū)間,發(fā)生鐵素體的再結晶,而950℃時,冷卻過程中依次發(fā)生鐵素體轉(zhuǎn)變、珠光體轉(zhuǎn)變和貝氏體相變。同時建立了再結晶鐵素體晶粒尺寸經(jīng)驗模型,擬合相關系數(shù)為0.9830。等溫熱處理力學性能模型的建立。通過等溫熱處理的ST52-3G鋼力學性能數(shù)據(jù)分析,并依據(jù)JMAK模型及再結晶和未再結晶部分加權平均的思想建立了ST52-3G鋼的力學性能模型,結果表明:屈服強度、抗拉強度和伸長率的擬合相關系數(shù)分別達到0.9761、0.9175和0.9429,平均絕對誤差分別為14.54 MPa、23.44 MPa和1.07%,平均相對誤差分別為2.47%、2.67%、6.72%,可見模型具有較高的精度,為實際生產(chǎn)提供理論參考。
[Abstract]:With the development of industry, especially the development of automobile manufacturing industry, the demand for cold-rolled steel plate has been increasing rapidly, because cold-rolled steel plate has the characteristics of high function, abundant raw materials, relatively low production cost and batch production. Determine its short period of time difficult to replace. With the increasing demands of customers on steel properties, improving the mechanical properties and performance prediction of steel has become a research hotspot, and heat treatment is the most commonly used method to improve the microstructure and properties of steel. In order to obtain more suitable steel materials for various purposes, it is necessary to study them in depth. In this paper, the microstructure evolution law, especially the recrystallization law of ferrite, is studied under different isothermal heat treatment temperature and holding time according to the mechanical properties of cold rolled ST52-3G steel sheet and Gleeble-1500D. The mechanical properties of different isothermal heat treatment temperature and holding time are predicted. The main contents of this thesis are as follows: determination of the continuous cooling phase transformation curve of supercooled austenite in the steel of 1: ST52-3G (Continuous Cooling Transformation-CCT). The expansion curve of ST52-3G steel was obtained by using the expansion instrument of Gleeble-1500D thermal simulator, and the phase transition point by means of tangent method. The CCT curve of ST52-3G steel was obtained by means of metallographic hardness method. At the same time, the critical transition point of the rapid heating is improved significantly than that of the standard condition at 50 鈩，

本文編號：2154492