本文關(guān)鍵詞： 球墨鑄鐵 固溶強(qiáng)化 抗拉強(qiáng)度 鐵素體　出處：《蘭州理工大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：球墨鑄鐵由于其較低的生產(chǎn)成本,良好的力學(xué)性能等特點(diǎn),在工業(yè)機(jī)械構(gòu)件中已得到了廣泛的應(yīng)用。這些機(jī)械構(gòu)件主要應(yīng)用于對材料要求較高的工作條件,如受力比較復(fù)雜,較高的強(qiáng)度、較高的韌性和耐磨性等。廣泛應(yīng)用在汽車行業(yè)的曲軸、汽缸蓋;燃汽輪機(jī)行業(yè)的進(jìn)排氣缸等零部件上。由于球墨鑄鐵使用行業(yè)的特點(diǎn),因此對于零部件的產(chǎn)品質(zhì)量要求也非常高,除常規(guī)的力學(xué)性能要求外,還要有耐高溫或低溫、耐腐蝕性、耐機(jī)械沖擊以及良好的尺寸穩(wěn)定性等。隨著對于球墨鑄鐵材料的進(jìn)一步研究,許多鑄鋼材料、灰口鑄鐵已經(jīng)被球墨鑄鐵所取代,球墨鑄鐵已發(fā)展成為一種非常重要的工程材料。隨著科學(xué)技術(shù)的進(jìn)一步發(fā)展,鑄鐵生產(chǎn)技術(shù)也在不斷創(chuàng)新,目前生產(chǎn)的球墨鑄鐵牌號有QT400-18、QT500-7、QT600-3、QT700-2等材料。QT500-7、QT600-3基體組織中含有30%~60%珠光體,采用此類球墨鑄鐵的抗拉強(qiáng)度高,但其屈服強(qiáng)度和伸長率較低。另外QT500-7、QT600-3球墨鑄鐵與QT400-18全鐵素體基體球墨鑄鐵相比,其加工性能比較差,由于基體組織中含有一定量的珠光體,因此對于加工刀具磨損相對其它球墨鑄鐵磨損較大。為了獲得更高抗拉強(qiáng)度、屈服強(qiáng)度、伸長率及更好的加工性能的球墨鑄鐵,本論文充分利用硅元素的固溶強(qiáng)化作用,選擇Ba Si孕育劑對鐵液進(jìn)行孕育處理,Fe Si Mg球化劑對鐵液進(jìn)行球化處理,即通過固溶某種溶質(zhì)元素來形成固溶體從而強(qiáng)化金屬。利用硅元素溶入鐵液中形成固溶體,其固溶體中溶質(zhì)原子造成晶格畸變,從而增加位錯運(yùn)動的阻力,阻礙位錯運(yùn)動,進(jìn)而增加固溶體的強(qiáng)度與硬度。當(dāng)溶質(zhì)原子的濃度處于適當(dāng)范圍時,合金的強(qiáng)度和硬度可以明顯提高,但合金的塑形和韌性會降低。試驗研究證明,利用硅元素固溶強(qiáng)化,在鐵液中保證一定量的硅含量,已經(jīng)成功的研發(fā)出了生產(chǎn)QT500-14、QT600-10全鐵素體基體牌號的球墨鑄鐵工藝方法,獲得了較高牌號的球墨鑄鐵材料,解決了該材料屈服強(qiáng)度、伸長率較低以及加工性能差等問題。
[Abstract]:Nodular cast iron due to its low production cost, good mechanical properties, has been widely used in industrial machinery components. These mechanical components mainly used for materials demanding working conditions, such as stress is complex, high strength, high toughness and wear resistance. The crankshaft. Widely used in the automobile industry of the cylinder cap; the exhaust cylinder and other parts of gas turbine industry. Due to the characteristics of ductile iron industry, so the product quality requirements of parts is very high, in addition to the requirements of the conventional mechanical properties, but also have high temperature or low temperature, corrosion resistance, and good resistance to mechanical shock the size of stability. As for the further study of ductile iron material, many steel, gray cast iron has been replaced by ductile iron, nodular cast iron has become a very important project. The material. With the further development of science and technology, iron production technology is also in constant innovation, the current production of ductile iron grades are QT400-18, QT500-7, QT600-3, QT700-2 and other materials.QT500-7, QT600-3 in the matrix containing 30%~60% pearlite, with high tensile strength such as ductile iron, but its yield strength and elongation is low. The addition of QT500-7, QT600-3 and QT400-18 ductile iron ferrite matrix ductile iron, its processing performance is poor, because contain a certain amount of pearlite in the matrix, so the machining tool wear it relative to the ductile iron wear greatly. In order to obtain a higher tensile strength, yield strength, ductile iron processing performance elongation and better, this paper makes full use of the solid solution strengthening effect of silicon Ba Si inoculants on liquid iron inoculation, Fe Si Mg spheroidizing agent for molten iron spheroidizing treatment, Through some kind of solution to solute to form a solid solution to strengthen the metal. The solid solution is formed of silicon dissolved in liquid iron, the solid solubility of solute atoms caused by lattice distortion in the body, thereby increasing the resistance to dislocation motion, hinder dislocation motion, and increase the strength and hardness of the solution. When the concentration of solute atoms in a proper range, the strength and hardness of the alloy can be improved obviously, but the plasticity and toughness of alloy will decrease. The experimental study proves that the use of silicon element solid solution strengthening, guarantee a certain amount of silicon content in molten iron, has successfully developed the production of QT500-14, QT600-10 ferrite matrix grade ball graphite cast iron process, obtained higher grades of ductile iron material, solves the problem of material yield strength, lower elongation and poor processing performance.

【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TG255

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本文編號：1460721