【摘要】：近些年,制造業(yè)技術(shù)不斷進(jìn)步,汽車行業(yè)的需求也不斷提高,對零件的力學(xué)性能有了更高的要求,并且為了節(jié)約能源減少排放量開始越來越多地使用高強(qiáng)鋼。但是由于超高強(qiáng)度鋼冷沖壓成形后強(qiáng)度可以達(dá)到1000MPa,這就導(dǎo)致超高強(qiáng)度鋼冷沖壓成形具有回彈大,零件精度低等問題。然而傳統(tǒng)的冷沖壓工藝在高強(qiáng)鋼的成形過程中存在很多工藝問題,為了解決這些問題人們開始關(guān)注高強(qiáng)鋼熱成形。人們逐漸認(rèn)識到通過不同的熱成形工藝可以得到不同的組織,不同性能的零件,這樣根據(jù)零件的不同要求設(shè)計(jì)不同的熱成形工藝非常必要。本文從熱成形的基本原理入手,通過改變模具的溫度及成形工藝,探究模具溫度及各種成形工藝對零件的力學(xué)性能的影響。本文以USibor1500(22MnB5)作為研究對象,針對模具溫度,保壓時(shí)間,冷卻工藝設(shè)計(jì)了不同的實(shí)驗(yàn)方案。前期通過數(shù)值分析的方法做了初步的分析,后期進(jìn)行了平模實(shí)驗(yàn),并且觀察了組織結(jié)構(gòu),研究了不同工藝不同拉伸速率下零件的力學(xué)性能。結(jié)果表明:逐漸升高模具的溫度,板料冷卻速率下降,零件微觀組織中貝氏體含量增加,零件的抗拉強(qiáng)度降低,硬度降低,延展率增加。零件雖然犧牲了強(qiáng)度,但是獲得了更好的變形和碰撞的能力。本文還根據(jù)采集溫度的曲線,與溫度模擬進(jìn)行了對比,找到了較為準(zhǔn)確的模擬方法,并且跟實(shí)際溫度曲線做了對比。
[Abstract]:In recent years, with the development of manufacturing technology and the increasing demand of automobile industry, the mechanical properties of parts have higher requirements, and in order to save energy and reduce emissions, more and more high-strength steel has been used. However, the strength of ultra-high strength steel can reach 1000MPa after cold stamping, which leads to the problems of large springback and low precision of parts. However, the traditional cold stamping process has many problems in the forming process of high strength steel. In order to solve these problems, people begin to pay attention to the hot forming of high strength steel. People have come to realize that different parts with different structures and properties can be obtained by different hot forming processes, so it is necessary to design different hot forming processes according to different requirements of parts. Based on the basic principle of hot forming, the influence of die temperature and various forming processes on the mechanical properties of parts is investigated by changing the temperature and forming process of the die. In this paper, USibor1500 (22MnB5) is taken as the research object. Different experimental schemes are designed for mold temperature, pressure holding time and cooling process. The preliminary analysis was done by numerical analysis in the early stage, and the flat die experiment was carried out in the later stage, and the microstructure was observed, and the mechanical properties of the parts with different drawing rates were studied. The results show that the cooling rate of sheet metal decreases, the bainite content in the microstructure increases, the tensile strength decreases, the hardness decreases and the extension rate increases with increasing the die temperature. The parts sacrifice strength, but gain better ability to deform and collide. According to the curve of collecting temperature, this paper compares it with temperature simulation, finds a more accurate simulation method, and makes a comparison with the actual temperature curve.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG142.1

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