共查询到18条相似文献,搜索用时 218 毫秒
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连铸坯下线至加热炉的温度制度及其表层组织演变与热送或粗轧裂纹密切相关.基于热模拟实验分析了送装工艺对奥氏体转变特征和再加热晶粒尺寸的影响.高温共聚焦激光扫描显微镜原位观察表明,含Nb J55钢在双相区700℃热装时,组织为晶界膜状先共析铁素体、魏氏体和大量残留奥氏体,再加热至1200℃,奥氏体晶粒大小、位置都不变;单相区600℃温装时,组织为大量铁素体+珠光体,再加热至1200℃时,奥氏体晶粒明显细化.马弗炉模拟SS400钢双相区不同热装温度发现,铁素体转变量至少达70%时才可细化再加热后的奥氏体晶粒.在临界转变量以上,基体中铁素体转变量越多晶粒细化程度越明显. 相似文献
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采用实验室钢坯室温装炉和炼钢-连铸-直接轧制的不同方法,研究了用钢坯室温装炉工艺和连铸连轧工艺生产X70管线钢时,不同的装炉温度对成品组织性能的影响。结果表明,室温装炉比1100℃热装的钢板晶粒尺寸细小,位错密度高,因而强度较高,韧性较好;而1100℃热装的钢板析出物尺寸比室温装炉时细小、分散;采用两种装炉方式轧制的钢板均能满足X70管线钢的性能要求。 相似文献
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采用Gleeble 3500热模拟试验机试验研究了直接车削用非调质钢SG4201(/%:0.42C,0.50Si,1.40Mn,0.009P,0.005S,0.02Nb,0.06V,0.015N)在1000~1250℃加热0~300 s的奥氏体晶粒长大行为,并建立了该钢奥氏体晶粒长大模型。试验结果表明,加热时间30 s时,奥氏体晶粒粗化温度和铌迅速大量固溶的温度为1100℃左右;奥氏体晶粒长大激活能约为110.8 kJ;确立SG4201钢铸坯均热不宜超过1150℃。工业生产结果表明,当铸坯均热温度≤1150℃,终轧温度800~850℃,轧后冷却速度30~35℃/s时,SG4201钢的力学性能为抗拉强度927 MPa,屈服强度687 MPa,延伸率23.5%,断面收缩率57%,U-冲击功48 J,HBW硬度值265。 相似文献
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用热模拟实验机Gleeble-1500模拟了F45MnV钢(%:0.44C、1.18Mn、0.10V)热轧过程中的加热、轧制及冷却参数。通过实验发现,加热温度由950℃增至1100℃,钢中奥氏体平均晶粒尺寸由25.7μm增加至84.3μm;加热温度为1000~1050℃时,奥氏体晶粒尺寸为64.0~62.8μm,在该温度范围内轧制,有利于钢的质量控制和保证性能的稳定;随冷速由0.25℃/s增加至2℃/s,变形量70% 900℃,终轧的F45MnV钢的抗拉强度由815 MPa迅速提高至960MPa。 相似文献
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通过固溶度积公式计算及热模拟实验,对不同热装和加热温度条件下的无取向硅钢铸坯中析出相进行了研究.在低于950℃热装时,铸坯中AlN的析出量和尺寸不再变化,但MnS和AlN-MnS的数量及平均尺寸随着热装温度降低而进一步增加,并在温度低于600℃时达到最大值后保持不变.与1200℃相比,1100℃加热的铸坯中AlN、MnS的总固溶量相对更少.相比850℃热装,600℃热装再加热到1100℃的铸坯中AlN和MnS的总固溶量更少,且AlN和MnS尺寸更大.合适的热装温度和加热温度分别为600℃和1100℃. 相似文献
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采用热模拟试验研究了含钼双相钢DP600在不同冷却模式、转变温度和冷却速率时的显微组织转变,分析了相变后的马氏体比例和晶粒度级别,根据热模拟结果设计了DP600钢的生产工艺,并探讨了钼元素对双相钢的影响。结果表明,DP600钢在热轧组织转变时,两段式冷却工艺比一段式工艺形成的马氏体细小,且晶粒度提升1级。奥氏体向铁素体转变过程中,存在最佳相变温度平衡点;590 ℃以上减缓DP600钢铁素体+珠光体的过冷转变速率,可以细化晶粒、增加马氏体比例。生产的DP600钢金相显微组织为铁素体+马氏体,马氏体比例为17%,晶粒度为11级;纵向、横向抗拉强度分别为592和620 MPa,伸长率分别为28.5%和26.5%。钼元素可以强烈抑制C- Si- Mn- Cr- Mo系DP600钢的铁素体转变,缩小铁素体转变区。 相似文献
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为了推进高强钢筋工业应用,以Nb-V复合微合金化600 MPa级高强钢筋为研究对象,采用高温激光共聚焦显微镜研究了加热温度对晶粒长大规律的影响,并进行了工业试制。结果表明,随着加热温度升高、保温时间延长,奥氏体晶粒尺寸增大;加热温度从1 180提高至1 270 ℃,保温60 min,奥氏体平均晶粒尺寸从58.7提高至85.1 μm。工业试制中,加热温度由1 200提高至1 270 ℃,珠光体比例增加,珠光体团尺寸增大,屈服强度和抗拉强度升高,伸长率下降,拉伸断口形貌由韧性断裂转变为准解理脆性断裂;当加热温度为1 200~1 250 ℃时,屈服强度为640~659 MPa,抗拉强度为823~846 MPa,强屈比为1.28~1.30,断后伸长率为16.6%~19.2%,最大力伸长率为10.6%~13.0%。 相似文献
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利用金相观察、扫描电镜及能谱分析和透射电镜等手段,对热装热轧微合金钢板出现的表面裂纹进行分析研究,并与使用同批次连铸坯冷装热轧无裂纹的钢板进行比较,分析产生表面裂纹的原因。实验结果表明热装热轧微合金钢板产生表面裂纹的原因是铸坯冷却或加热过程中Cu、As低熔点元素在奥氏体晶界的偏聚。与热装热轧板相比,冷装热轧板晶粒尺寸小直径在10μm左右,而热装热轧板晶粒尺寸大且不均匀。热轧板析出物尺寸在15~25nm之间,裂纹源处较基体多,大量细小的Nb(C,N)化合物在奥氏体晶界析出,降低了晶界强度。 相似文献
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The continuous cooling transformation behavior, the effect of coiling temperature on microstructure and mechanical properties, and strengthening mechanisms of Ti microalloyed high strength hot strip steel were systematically investigated by thermal simulation testing machine, laboratory rolling mill, SEM and HR-TEM. The dynamic CCT curve was established. The results show that the austenite to ferrite and pearlite transformation takes place when the cooling rate is less than 1??/s. The austenite to bainite transformation accompanied with austenite to ferrite and pearlite transformation takes place when the cooling rate is in the range of 5 ??/s to 10 ??/s. The bainitic transformation temperature is about 600??. The amount of granular bainite decreases, while the amount of lath bainite increases with the increase of cooling rate in the range of 20??/s to 50??/s. Furthermore, the study on the effect of coiling temperature on the microstructure and mechanical properties of experimental steel has shown that the strength and plasticity of tested steel are improved with decreasing the coiling temperature. When the coiling temperature is 550?棬the experimental steel possesses optimal mechanical properties owing to the grain refinement and precipitation of nano-scale TiC particles. And the tensile strength, yield strength and elongation of tested steel were 742MPa, 683MPa and 22??5%, respectively. 相似文献
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In order to develop a comprehensive understanding of the effect of hot charging temperature on the hot ductility of a Nb‐containing steel, direct hot charging process was simulated by using a Gleeble thermo stress/strain machine. Three kinds of thermal histories were introduced to assess the hot ductility of the steel during continuously cast, hot charging, and cold charging process by means of hot tensile test in relation to surface cracking of hot charging processed steel slabs. The ductility of the specimens charged at the temperature within the range of ferrite/austenite two‐phase region and charged at the temperature just below the Ar1 of the steel is largely reduced. These results can be ascribed to the retained ferrite films at the boundaries of austenite encouraging voiding at the boundaries and these voids gradually link up to give failure around 750°C, and the combination of inhogeneous austenite grain size and precipitations aggravating the ductility trough by encouraging grain boundary sliding at 950°C. The steel via the conventional cold charge process experienced a complete phase transformation from austenite to ferrite and pearlite structure during the cooling to the ambient temperature. This steel can be charged into a reheating furnace and rolled without experiencing hot embrittlement due to the recrystallization and the precipitates are trapped inside a newly formed grain of austenite. In comparison with the hot ductility results, the hot tensile strength is only slight influenced by the charging temperature. 相似文献
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研究了1050~1150℃固溶处理对20 kg真空感应炉熔炼的690镍基合金(%:0.020C、29.93Cr、9.82Fe、0.19Al、0.25 Ti、0.023Nb、0.012Mo、0.004 2N)1.0mm冷轧板的组织和力学性能的影响。结果表明,当固溶温度从1050℃提高至1100℃,平均晶粒尺寸呈线性增长,从12μm提高到29μm,超过1100℃时晶粒尺寸快速增长,1150℃时平均晶粒尺寸达58μm;1090℃以上固溶处理时,合金中富铬碳化物完全溶解;690镍基合金主要强化机制为细晶强化,随固溶温度升高,合金室温抗拉和屈服强度分别从780 MPa和400 MPa降至662.5 MPa和250MPa,伸长率由40%提高至51.75%。 相似文献