退火和轧制调控微纳结构不锈钢和碳钢组织及其演变机制

发布时间：2018-03-22 01:17

  本文选题：铝热反应　切入点：微纳结构　出处：《兰州理工大学》2016年博士论文　论文类型：学位论文

【摘要】：本文通过铝热法制备了具有微纳结构的304、316L不锈钢,20、45亚共析碳钢,其直径可达200mm,厚度10mm左右,并研究了不锈钢退火温度和时间、轧制温度和变形量、先开坯再不同温度和变形量轧制对组织的影响;碳钢退火温度和时间、600℃轧制变形量对组织的影响。通过分析不锈钢中纳米晶奥氏体、亚微米晶奥氏体和铁素体晶粒尺寸,以及它们的体积分数的变化;亚共析碳钢中珠光体体积分数、片层间距和渗碳体形状等,根据研究结果提出了微纳组织演化机制。1.对铝热反应法制备的微纳结构304、316L不锈钢不同时间和温度退火后的组织研究发现,800℃退火后,铁素体晶粒尺寸随退火时间的延长逐渐长大;1000℃退火后,随退火时间的延长基本不变,并有Fe Ni Cr Al相析出。纳米晶奥氏体晶粒尺寸随退火温度的升高或退火时间的增加不断增加,体积分数不断减小,温度越高或退火时间越长,这种变化趋势越明显。2.对304和316L不锈钢800℃变形量≤60%轧制后,铁素体晶粒尺寸随变形量的增加而增大,变形量60%轧制后,随变形量的增加而减小;304不锈钢1000℃轧制后,随变形量的增加基本不变。800℃变形量≤40%轧制后,纳米晶奥氏体晶粒尺寸随变形量的增加而长大,体积分数减少;变形量≥60%轧制后,304不锈钢中纳米晶奥氏体晶粒消失转变为亚微米晶奥氏体晶粒,316L不锈钢中本身的纳米晶消失,出现由亚微米晶破碎产生的纳米晶。304不锈钢800和1000℃变形量≤40%轧制后,亚微米晶奥氏体体积分数随变形量的增加而增加;800℃变形量40%轧制后,随变形量的增加而减少;1000℃变形量≥60%轧制后,亚微米晶奥氏体晶粒消失。316L不锈钢800℃不同变形量轧制,随轧制变形量的增加,亚微米晶奥氏体晶粒尺寸减小,体积分数减少。3.304不锈钢开坯后700和600℃变形量≤50%轧制后,随变形量的增加,铁素体晶粒尺寸增加,变形量为70%轧制后基本不变。随变形量的增加,纳米晶奥氏体晶粒尺寸增加,亚微米晶奥氏体晶粒尺寸减小并分布越来越均匀。700℃轧制后,随变形量的增加,纳米晶和亚微米晶奥氏体体积分数逐渐减少;600℃变形量为50%轧制后,纳米晶奥氏体体积分数减小,亚微米晶奥氏体体积分数增加;变形量为70%轧制后,纳米晶奥氏体体积分数增加,亚微米晶奥氏体体积分数减小。4.316L不锈钢开坯后700℃变形量≤50%轧制后,纳米晶奥氏体晶粒消失,随变形量的增加,铁素体晶粒尺寸和亚微米晶奥氏体体积分数不变;变形量为70%轧制后,亚微米晶奥氏体晶粒破碎产生纳米晶奥氏体晶粒,亚微米晶奥氏体体积分数下降,铁素体晶粒尺寸增加。600℃轧制后,随变形量的增加,铁素体晶粒逐渐破碎减小;变形量≥50%轧制后,亚微米晶奥氏体晶粒破碎,有纳米晶奥氏体晶粒出现,并随着变形量的增加,亚微米晶和纳米晶奥氏体晶粒尺寸减小,纳米晶奥氏体体积分数增加,亚微米晶奥氏体体积分数减小。5.20和45钢经600℃退火后,随退火时间的延长,珠光体体积分数基本不变,珠光体片层间距逐渐增加。20钢经800℃退火2h后,珠光体基本完全球化;退火16h后,珠光体消失,材料表面析出Fe3C。45钢经600℃退火后,当退火时间≤4h时,珠光体全部为片层状;当退火时间≥6h时,珠光体开始球化,并且随着退火时间的延长,珠光体球化越显著。45钢经800℃退火2h后,珠光体为层状,退火16h后,珠光体大部分球化。6.20和45钢在600℃下不同变形量轧制后,随变形量的增加,珠光体体积分数基本不变。变形量为20%轧制后,珠光体组织中的渗碳体开始破碎;变形量为40%轧制后,片状渗碳体破碎为棒状渗碳体;变形量为60%轧制后,部分棒状渗碳体破碎为球状渗碳体;变形量为80%轧制后,渗碳体破碎成亚微米颗粒;变形量为90%轧制后,20钢组织中的渗碳体继续破碎成纳米颗粒;而45钢组织中的球状渗碳体长大。
[Abstract]:This paper through the aluminum thermal preparation of micro nano structure of 304316L stainless steel with 20,45 hypoeutectoid steel, its diameter is 200mm, thickness of about 10mm, and studied the stainless steel annealing temperature and time, the rolling temperature and deformation, the first blooming again in different temperature and rolling deformation on group effect; annealing temperature and carbon steel time effect of deformation on Microstructure of 600 degrees. Through the analysis of nanocrystalline stainless steel rolling in austenite, sub micron austenite and ferrite grain size, and changes in their volume fraction; pearlite hypoeutectoid carbon in volume fraction, the lamellar spacing and cementite shape, according to the study results of the research organization the micro nano structure of 304316L stainless steel in different temperature and time after annealing in micro nano microstructure evolution mechanism of.1. prepared by aluminothermic reaction, 800 DEG C after annealing, the ferrite grain size increases with the extension of annealing time Grow up; 1000 DEG C after annealing, with prolonging annealing time is basically unchanged, and the Fe Ni Cr Al precipitates. Increasing nanocrystalline austenite grain size with annealing temperature or annealing time increasing, the volume fraction decreases, the higher the temperature or annealing time is longer, the more obvious trend of.2. 304 and 316L 800 stainless steel deformation is less than or equal to 60% DEG C after rolling, ferrite grain size increases with the increase of the amount of deformation and deformation after rolling 60%, decreases with the increase of deformation temperature of 1000 DEG C; 304 stainless steel after rolling, with the increase of deformation of the base deformation is less than or equal to 40% DEG.800 unchanged after rolling nanocrystalline austenite grain size grows up with the increase of deformation, the volume fraction decreased; deformation is more than 60% after rolling, the nanocrystalline austenite grain in 304 stainless steel disappeared into submicron grained austenite grain, nanocrystalline 316L stainless steel in itself Disappeared, nanocrystals of.304 stainless steel produced by sub micron grain crushing 800 and 1000 less than 40% DEG C deformation after rolling, sub micron grained austenite volume fraction increases with the increase of deformation; 800 DEG C after rolling deformation of 40%, and decreased with the increase of deformation; 1000 degrees deformation is more than 60% after rolling submicron grained austenite grains disappeared.316L stainless steel with different deformation temperature of 800 DEG C with rolling, the rolling deformation increases, sub micron grain austenite grain size decreases, the volume fraction of.3.304 is less than 700 and 50% stainless steel rolling deformation of 600 DEG C after blooming, with the increase of deformation, the ferrite grain size increases, deformation 70% after rolling basically unchanged. With the increase of the amount of deformation of the nanocrystalline austenite grain size increases, sub micron grain austenite grain size decreases and the distribution becomes more uniform.700 DEG C after rolling, with the increase of the amount of deformation of nano and submicron crystal The volume fraction of austenite decreases gradually; 600 degrees deformation is 50% after rolling, nanocrystalline austenite volume fraction decreases, submicron crystalline volume fraction of austenite increases; deformation is 70% after rolling, nanocrystalline austenite volume fraction, submicron crystalline volume fraction of austenite decreases after 700.4.316L stainless steel billet deformation is less than or equal to 50% DEG C after rolling, the nanocrystalline austenite grain disappears, along with the increase of deformation, the ferrite grain size and submicron crystalline volume fraction of austenite unchanged; deformation is 70% after rolling, sub micron grain austenite grain crushing of nanocrystalline austenite grains decreased, submicron crystalline volume fraction of austenite, ferrite grain size increased by.600 C after rolling, with the increase of the amount of deformation, the ferrite grain gradually broken decreases; deformation is more than 50% after rolling, sub micron grain austenite grain crushing, nanocrystalline austenite grain, and with the With the increase of deformation, sub micron grained and nanocrystalline austenite grain size decreases, the increase of the volume fraction of nanocrystalline austenite, sub micron austenite volume fraction decreased.5.20 and 45 steel after annealing at 600 DEG C, with the increase of annealing time, the pearlite volume fraction is essentially the same, the interlamellar spacing increased gradually in.20 steel with 800 C after 2H annealing, pearlite spheroidization annealing completely; after 16h, pearlite disappeared, surface precipitation of Fe3C.45 steel after annealing at 600 DEG C, when the annealing time is less than 4h, all of the lamellar pearlite; when the annealing time is greater than or equal to 6h, start pearlite spheroidization, and with the increase of annealing time, the pearlite spheroidization significant.45 steel after annealing at 800 DEG C after 2h, 16h after annealing for lamellar pearlite, pearlite spheroidization, most of.6.20 and 45 steel under 600 degrees different deformation after rolling, with the increase of the amount of deformation of the pearlite volume fraction is essentially the same 20%. The deformation after rolling, cementite in pearlite began breaking; deformation is 40% after rolling, for rod cementite lamellar cementite broken; deformation is 60% after rolling, as part of the rod spheroidite cementite broken; deformation is 80% after rolling, the cementite is broken into sub micron particles; deformation is 90% after rolling, 20 cementite in steel structure to break into nano particles; and 45 spherical cementite in the microstructure of growing up.

【学位授予单位】：兰州理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG156.2;TG335
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本文编号：1646409