固溶處理對錳鎳系奧氏體球墨鑄鐵低溫?cái)嗔烟卣鞯挠绊?/H1>
發(fā)布時間：2018-02-02 00:33
本文關(guān)鍵詞： 錳元素 碳化物 固溶處理 沖擊韌性 斷裂機(jī)理 出處：《沈陽工業(yè)大學(xué)》2017年碩士論文 論文類型：學(xué)位論文
【摘要】：奧氏體球墨鑄鐵具有良好的機(jī)械性能和物理性能,自誕生起就被廣泛應(yīng)用于工業(yè)生產(chǎn)中。目前,大多數(shù)生產(chǎn)方式是通過添加大量鎳和少量錳來得到奧氏體基體,且以常溫和高溫應(yīng)用為主。為了探究高錳含量下,組織形貌和基體性能的變化及奧氏體球墨鑄鐵的低溫性能,本研究通過不同含量的Mn對組織和性能造成的影響進(jìn)行探究,并利用固溶處理,分析它們的斷裂特征,找到一種性能上接近高鎳奧氏體球墨鑄鐵的錳鎳系奧氏體球墨鑄鐵。通過觀察錳含量不同的奧氏體球墨鑄鐵的金相組織,能夠發(fā)現(xiàn),Mn雖然作為奧氏體化元素能夠促進(jìn)奧氏體形成,但對石墨的球化起抑制作用,并會加快鐵液的冷卻速度導(dǎo)致晶界上產(chǎn)生大量碳化物,這些碳化物會影響材料的力學(xué)性能。采用固溶處理能夠使晶界碳化物溶解,提高奧氏體球墨鑄鐵的力學(xué)性能,但是對石墨的球化等級并無明顯影響,這仍制約了性能的提高。在16Mn-8Ni、12Mn-8Ni、12Mn-10Ni和7Mn-10Ni四種種成分中,7Mn-10Ni的球化等級最高。通過觀察裂紋的擴(kuò)展路徑,發(fā)現(xiàn)了斷裂前后起裂區(qū)域V口附近形貌的變化,對比四組數(shù)據(jù)可以發(fā)現(xiàn),16Mn-8Ni-2.3C-3Si、12Mn-8Ni-2.3C-3Si、12Mn-10Ni-2.3C-3Si和7Mn-10Ni-2.3C-3Si四種種成分的奧氏體球墨鑄鐵在鑄態(tài)時,常溫下斷裂的裂紋都是在V口處的晶界碳化物上萌生并沿碳化物擴(kuò)展的。但是,在固溶處理后,它們的裂紋變?yōu)樵赩口處的缺陷處萌生,沿石墨球擴(kuò)展,這種變化與組織的力學(xué)性能發(fā)生變化有關(guān)。為了分析低溫下7Mn-10Ni-2.3C-3Si奧氏體球墨鑄鐵的沖擊韌性,選取-30℃、-60℃、-100℃和-196℃四種溫度進(jìn)行沖擊試驗(yàn)。結(jié)果表明,鑄態(tài)及固溶處理后的數(shù)值都隨溫度降低而降低,但固溶處理后性能較高。分析了低溫沖擊過程中屈服載荷Fy、最大載荷Fm和韌性斷裂帶Dmp1的變化。發(fā)現(xiàn)屈服載荷Fy不受固溶處理和溫度的影響,韌性斷裂帶Dmp1和沖擊韌性成正比。最大載荷Fm則表現(xiàn)出先增后減的變化趨勢。通過分析斷口形貌的改變,解釋了7Mn-10Ni-2.3C-3Si奧氏體球墨鑄鐵的斷裂機(jī)理。鑄態(tài)時,7Mn-10Ni-2.3C-3Si奧氏體球墨鑄鐵在室溫下的斷裂表現(xiàn)出韌窩斷裂與準(zhǔn)解理斷裂的混合斷裂方式,在低溫下的斷裂則是由于晶界碳化物處產(chǎn)生的微裂紋擴(kuò)展導(dǎo)致的。而在固溶處理后,7Mn-10Ni-2.3C-3Si奧氏體球墨鑄鐵在常溫下表現(xiàn)出明顯的韌窩斷裂方式,準(zhǔn)解理斷裂形貌消失。隨溫度降低,會突然發(fā)生沿晶斷裂,隨著溫度的降低,沿晶斷裂面積增大,最終變?yōu)榇嘈詳嗔选?br/>[Abstract]:Austenitic ductile iron has good mechanical and physical properties and has been widely used in industrial production since its birth. At present, most production methods are to obtain austenitic matrix by adding a large amount of nickel and a small amount of manganese. In order to study the changes of microstructure and matrix properties and the low temperature properties of austenitic ductile cast iron under high manganese content, the main applications were at room temperature and high temperature. In this study, the effects of different contents of mn on microstructure and properties were investigated, and their fracture characteristics were analyzed by solution treatment. An austenitic ductile iron of manganese and nickel series with similar properties to high nickel austenitic ductile iron was found. The metallographic structure of austenitic ductile iron with different manganese content was observed. Although mn as an austenitizing element can promote the formation of austenite, it can inhibit the spheroidization of graphite and accelerate the cooling rate of molten iron, resulting in a large number of carbides on grain boundaries. These carbides will affect the mechanical properties of the materials. The solution treatment can dissolve the carbide at grain boundary and improve the mechanical properties of austenitic ductile iron, but it has no obvious effect on the spheroidization grade of graphite. This still restricts the improvement of properties in the four compositions of 16Mn-8NiO12Mn-8NiO12Mn-10Ni and 7Mn-10Ni. 7Mn-10Ni has the highest spheroidization grade. By observing the crack propagation path, the changes of the morphology near the V mouth of the fracture initiation region are found, which can be found by comparing the four groups of data. 16Mn-8Ni-2.3C-3Si 12Mn-8Ni-2.3C-3Si. The austenitic ductile cast iron with 12Mn-10Ni-2.3C-3Si and 7Mn-10Ni-2.3C-3Si is in the as-cast state. The cracks of fracture at room temperature all germinate on the grain boundary carbides at the V mouth and propagate along the carbides. However, after the solution treatment, the cracks of the cracks begin to germinate at the defects at the V mouth and propagate along the graphite spheroids. In order to analyze the impact toughness of 7Mn-10Ni-2.3C-3Si austenitic ductile iron at low temperature, we select -30 鈩，
本文編號：1483232
本文鏈接：http://sikaile.net/kejilunwen/jiagonggongyi/1483232.html
本文關(guān)鍵詞： 錳元素 碳化物 固溶處理 沖擊韌性 斷裂機(jī)理 出處：《沈陽工業(yè)大學(xué)》2017年碩士論文 論文類型：學(xué)位論文
【摘要】：奧氏體球墨鑄鐵具有良好的機(jī)械性能和物理性能,自誕生起就被廣泛應(yīng)用于工業(yè)生產(chǎn)中。目前,大多數(shù)生產(chǎn)方式是通過添加大量鎳和少量錳來得到奧氏體基體,且以常溫和高溫應(yīng)用為主。為了探究高錳含量下,組織形貌和基體性能的變化及奧氏體球墨鑄鐵的低溫性能,本研究通過不同含量的Mn對組織和性能造成的影響進(jìn)行探究,并利用固溶處理,分析它們的斷裂特征,找到一種性能上接近高鎳奧氏體球墨鑄鐵的錳鎳系奧氏體球墨鑄鐵。通過觀察錳含量不同的奧氏體球墨鑄鐵的金相組織,能夠發(fā)現(xiàn),Mn雖然作為奧氏體化元素能夠促進(jìn)奧氏體形成,但對石墨的球化起抑制作用,并會加快鐵液的冷卻速度導(dǎo)致晶界上產(chǎn)生大量碳化物,這些碳化物會影響材料的力學(xué)性能。采用固溶處理能夠使晶界碳化物溶解,提高奧氏體球墨鑄鐵的力學(xué)性能,但是對石墨的球化等級并無明顯影響,這仍制約了性能的提高。在16Mn-8Ni、12Mn-8Ni、12Mn-10Ni和7Mn-10Ni四種種成分中,7Mn-10Ni的球化等級最高。通過觀察裂紋的擴(kuò)展路徑,發(fā)現(xiàn)了斷裂前后起裂區(qū)域V口附近形貌的變化,對比四組數(shù)據(jù)可以發(fā)現(xiàn),16Mn-8Ni-2.3C-3Si、12Mn-8Ni-2.3C-3Si、12Mn-10Ni-2.3C-3Si和7Mn-10Ni-2.3C-3Si四種種成分的奧氏體球墨鑄鐵在鑄態(tài)時,常溫下斷裂的裂紋都是在V口處的晶界碳化物上萌生并沿碳化物擴(kuò)展的。但是,在固溶處理后,它們的裂紋變?yōu)樵赩口處的缺陷處萌生,沿石墨球擴(kuò)展,這種變化與組織的力學(xué)性能發(fā)生變化有關(guān)。為了分析低溫下7Mn-10Ni-2.3C-3Si奧氏體球墨鑄鐵的沖擊韌性,選取-30℃、-60℃、-100℃和-196℃四種溫度進(jìn)行沖擊試驗(yàn)。結(jié)果表明,鑄態(tài)及固溶處理后的數(shù)值都隨溫度降低而降低,但固溶處理后性能較高。分析了低溫沖擊過程中屈服載荷Fy、最大載荷Fm和韌性斷裂帶Dmp1的變化。發(fā)現(xiàn)屈服載荷Fy不受固溶處理和溫度的影響,韌性斷裂帶Dmp1和沖擊韌性成正比。最大載荷Fm則表現(xiàn)出先增后減的變化趨勢。通過分析斷口形貌的改變,解釋了7Mn-10Ni-2.3C-3Si奧氏體球墨鑄鐵的斷裂機(jī)理。鑄態(tài)時,7Mn-10Ni-2.3C-3Si奧氏體球墨鑄鐵在室溫下的斷裂表現(xiàn)出韌窩斷裂與準(zhǔn)解理斷裂的混合斷裂方式,在低溫下的斷裂則是由于晶界碳化物處產(chǎn)生的微裂紋擴(kuò)展導(dǎo)致的。而在固溶處理后,7Mn-10Ni-2.3C-3Si奧氏體球墨鑄鐵在常溫下表現(xiàn)出明顯的韌窩斷裂方式,準(zhǔn)解理斷裂形貌消失。隨溫度降低,會突然發(fā)生沿晶斷裂,隨著溫度的降低,沿晶斷裂面積增大,最終變?yōu)榇嘈詳嗔选?br/>[Abstract]:Austenitic ductile iron has good mechanical and physical properties and has been widely used in industrial production since its birth. At present, most production methods are to obtain austenitic matrix by adding a large amount of nickel and a small amount of manganese. In order to study the changes of microstructure and matrix properties and the low temperature properties of austenitic ductile cast iron under high manganese content, the main applications were at room temperature and high temperature. In this study, the effects of different contents of mn on microstructure and properties were investigated, and their fracture characteristics were analyzed by solution treatment. An austenitic ductile iron of manganese and nickel series with similar properties to high nickel austenitic ductile iron was found. The metallographic structure of austenitic ductile iron with different manganese content was observed. Although mn as an austenitizing element can promote the formation of austenite, it can inhibit the spheroidization of graphite and accelerate the cooling rate of molten iron, resulting in a large number of carbides on grain boundaries. These carbides will affect the mechanical properties of the materials. The solution treatment can dissolve the carbide at grain boundary and improve the mechanical properties of austenitic ductile iron, but it has no obvious effect on the spheroidization grade of graphite. This still restricts the improvement of properties in the four compositions of 16Mn-8NiO12Mn-8NiO12Mn-10Ni and 7Mn-10Ni. 7Mn-10Ni has the highest spheroidization grade. By observing the crack propagation path, the changes of the morphology near the V mouth of the fracture initiation region are found, which can be found by comparing the four groups of data. 16Mn-8Ni-2.3C-3Si 12Mn-8Ni-2.3C-3Si. The austenitic ductile cast iron with 12Mn-10Ni-2.3C-3Si and 7Mn-10Ni-2.3C-3Si is in the as-cast state. The cracks of fracture at room temperature all germinate on the grain boundary carbides at the V mouth and propagate along the carbides. However, after the solution treatment, the cracks of the cracks begin to germinate at the defects at the V mouth and propagate along the graphite spheroids. In order to analyze the impact toughness of 7Mn-10Ni-2.3C-3Si austenitic ductile iron at low temperature, we select -30 鈩，
本文編號：1483232
本文鏈接：http://sikaile.net/kejilunwen/jiagonggongyi/1483232.html
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