共查询到20条相似文献,搜索用时 458 毫秒
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采用带有不同空芯的铅锭模拟带液芯的连铸坯,在四机架连轧机上平立交替轧制,形成连轧时停止轧制并反转退出轧件,测量各道次的压下、宽展、前滑和芯部的压合值,并计算出各道次的秒流量和延伸系数,借此研究该工艺的可行性及连轧时带液芯轧件的变形情况。研究结果表明:用四机架连轧带液芯铸坯在工艺上、技术上是可行的。连铸坯带液芯连轧时的液芯率应小于20%。最好采用四辊万能轧机或采用凸透镜形状的连铸结晶器,以避免带液芯连轧时出现凹陷变形带。初步确定在所采用轧制条件下可轧合的最大液芯率为10%。 相似文献
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薄板坯连铸连轧CSP生产低碳钢板的组织特征 总被引:17,自引:3,他引:14
对珠钢CSP线生产的低碳钢(ZJ400)连铸坯及轧后的组织特征观察和硬度测定表明:CSP线生产的连铸坯铸态组织为较细的树枝晶,枝晶宽度为几微米到30um,靠近表面层的枝晶宽度与中心区域差别很小,经第一道次50%变形后,板坯组织明显细化,具有局部“树枝晶”特征,“枝晶”宽度约5um,中心区域硬度降低,成品薄板的晶粒尺寸平均为5um,大多呈尖角型。变形区位力,应变及温度分布的有限元模拟分析结果与实际组织分析结果吻合。 相似文献
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为了弄清BOF-LF-CSP工艺生产低碳钢的组织变化规律,对低碳钢SS400进行了铸态组织、第一轧制道次的形变组织以及成品板卷的组织测试与分析.结果表明:薄板坯铸态组织为较细的枝状晶,铸坯表面层和中心差别很小.经第一道次大压下变形后板坯的晶粒组织得到明显细化,表面至中心区域的晶粒尺寸及硬度存在梯度分布.低碳钢SS400成品薄板的组织很细,平均晶粒尺寸在5μm左右. 相似文献
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CSP薄板坯的铸态组织及力学性能特征 总被引:1,自引:0,他引:1
对CSP的铸坯组织、化学成分偏析、枝晶间距、轧制过程中的组织变化以及薄板的力学性能进行了研究。结果表明:CSP薄板坯的低倍组织在结构上和传统板坯没有本质区别,但薄板坯组织较为细密,柱状晶比较发达;第一道次轧完后中心部的疏松和偏析明显减轻,树枝晶沿轧制方向弯曲,但没有被打碎;CSP工艺生产的HSLC钢的力学性能与微合金化HSLA钢相当。 相似文献
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阐述了珠钢电炉-薄板坯连铸连轧流程VN微合金钢钒的析出规律、微观组织特征和强化机理。研究表明:在电炉-薄板坯连铸连轧流程采用VN微合金化,铸坯中析出以钒(C,N)为主,并有少量TiN或(Ti,V)(C,N)复合析出,平均粒度大约为40nm,热连轧开始前铸坯中大量存在的钒(C,N)能够抑制后续热连轧过程中变形奥氏体再结晶晶粒长大,使铁索体组织超细化;强化机制以细晶强化为主、沉淀强化为辅;采用VN微合金化技术开发的550MPa级VN微合金钢组织细化至3.0—4.0μm,产品具有良好的综合性能。 相似文献
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利用Gleeble1500-D热模拟试验机,模拟连铸工艺及4道次连轧工艺,对比添加稀土元素Nd对Q345B钢铸坯组织和控轧控冷组织的影响,通过单道次试验分析稀土Nd对动态再结晶、动态激活能的影响。结果表明:Q345B钢中加入稀土元素Nd,能够细化连铸坯的奥氏体晶粒,能够推迟轧制阶段动态再结晶的发生,提高动态再结晶激活能51.3 k J/mol,并对连轧后的控冷组织有显著的细化作用。 相似文献
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表层细晶化Q235中厚板轧制工艺的研究 总被引:1,自引:1,他引:0
采用Q235成分的连铸板坯,在首钢中厚板厂3300mm轧机上进行了中板表层组织细晶化的工业轧制实验,研究了轧制温度、轧制变形量分配、待温期间冷却方式对板材组织和性能的影响。结果表明,在奥氏体低温区增加精轧总变形量可以实现20mm成品板材的表层组织细化,屈服强度达到300MPa左右,铁素体晶粒达到8.5级,增加待温期间中间坯的水幕冷却有利于整个板材厚度截面的组织细化,屈服强度达到330MPa左右,铁素体晶粒达到9级,材料的强度接近Q345同规格板材的水平,具有优良的塑性和冲击韧性。 相似文献
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《钢铁研究学报(英文版)》2011,(Z1):595-599
In the present paper,controlled rolling and cooling processing was conducted by using a laboratory hot rolling mill.The influence of different processing parameters on the mechanical properties of low carbon cold forging steel was investigated.The results show that the faster cooling after the deformation (especially in low temperature rolling conditions) leads to the refinement of the ferrite grain.The specimen exhibits very good mechanical properties owing to the finer ferrite grains.The pearlite morphologies can also affect the mechanical properties of low carbon cold forging steel.The mechanical properties increase with decreasing final cooling temperature within the range from 650℃ to 570 ℃ due to the finer interlamellar spacing of pearlite colony.The mechanical properties of the specimens with fast cooling after the conventional rolling are not only better than those of the specimens with slow cooling after low temperature rolling,but also almost similar to those of the specimens with fast cooling after low temperature rolling.It is suggested that fast cooling after high temperature rolling (the conventional rolling) process would be of important industrial value. 相似文献
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A. Bodin J. Sietsman S. Van Der Zwaag 《Metallurgical and Materials Transactions A》2002,33(6):1589-1603
Laboratory rolling trials have been performed to investigate the development of microstructure and crystallographic texture
during and after intercritical rolling. The finishing temperature was varied over a wide range, and samples were taken just
prior to the last pass, after quenching following the last pass, after air cooling and coiling, and after accelerated cooling
and coiling. Cooling of the samples to the entry temperature for the last pass does not influence the texture of the sample,
nor do higher cooling rates after austenitic finishing within the range of cooling rates in this study, although it may cause
a refinement of the ferrite grains. Recrystallization after intercritical rolling leads to a decrease in texture intensity.
In the case of recrystallization of low-carbon steels, the nucleation mechanism is strain-induced boundary migration (SIBM),
which leads to unfavorable textures for deep drawing. In the case of recrystallization of interstitial-free (IF) steel after
ferritic rolling, the nucleation mechanism shifts from the SIBM mechanism at high finishing temperatures to subgrain coalescence
at (SGC) low finishing temperatures. The latter mechanism leads to more favorable textures for deep-drawing applications.
Transformation-induced (TI) nucleation explains the occurrence of a sudden increase in ferrite grain size after high-temperature
intercritical deformation of low-carbon (LC) steels. 相似文献
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为了研究TMCP工艺对低碳Ni-Nb钢显微组织转变类型和晶粒尺寸的影响规律,研究了不同TMCP工艺下的显微组织特征及其对力学性能的作用机理。结果表明,在未变形轧制情况下,当冷却速度小于5 ℃/s时,显微组织为铁素体和珠光体,铁素体晶粒尺寸随着冷却速度的增大而减小;在变形轧制情况下,随着冷却速度的增加,组织中的铁素体晶粒尺寸明显减小;当冷却速度增大到5 ℃/s时,微观组织中出现了大量粒状贝氏体。试制钢板试验表明,当冷却速度为4 ℃/s时,试验钢的组织为准多边形铁素体,可以有效提高钢的低温韧性;当冷却速度达到6 ℃/s时,试验钢微观组织中出现大量粒状贝氏体,明显降低钢的低温韧性。 相似文献
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制作直径10mm的试样以模拟铸坯表面组织,将试样分别在传统冷却模式下和控制冷却模式下进行冷却,通过对试样截面的微观组织形貌进行金相分析,从而研究冷却模式对铸坯表层组织结构的影响。试验得到如下结果:传统冷却条件下,试样边部为块状铁素体和珠光体,晶粒尺寸在10~200μm之间,中心位置为条状、针状铁素体和珠光体,晶粒粗大,组织不均。控制冷却条件下,试样均由块状铁素体和珠光体组成,晶粒尺寸在9.36~12.25μm之间,晶粒细小,组织均匀。控制冷却可以通过细化晶粒来提高铸坯表面的高温塑性从而对避免表面横裂纹的发生产生有利影响。 相似文献
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基于唐钢中厚板厂含铌钢板坯连铸生产实际,采用数值模拟方法研究了Q345B- Nb含铌钢板坯连铸过程实施铸坯角部二冷高温区角部组织多相变晶粒细化控冷工艺的可行性。结果表明,通过在结晶器窄面足辊下方增加6组针对铸坯角部强喷淋冷却的喷嘴结构,可使铸坯角部温度下降至约600 ℃,而后减少立弯段中下部3区与4区冷却水量,可使铸坯角部温度回升至900 ℃以上,满足铸坯角部多相变温度控制条件。在此基础上,将新控冷工艺应用于现场实际,实施铸坯二冷高温区多相变控冷新工艺后,铸坯角部距表面0~20 mm范围内的组织均可由传统工艺下“奥氏体+先共析铁素体膜”结构转变成“铁素体+珠光体”结构,且晶粒细化至不大于20 μm,铸坯抗裂纹能力大幅提高,含铌钢连铸坯角部裂纹率由原工艺的5.89%稳定控制在小于0.1%水平。 相似文献
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Lots of work has been done to investigate slab surface microstructure evolution during continuous casting in order to improve hot ductility and avoid transverse cracks.The slab surface microstructure after continuous casting was characterized by optical microscopy, and the precipitation behavior was investigated by transmission electron microscopy.At the same time, the mechanical properties of the slabs were measured using a Gleeble 1500D thermal simulator and the transformation temperatures were examined by means of a thermal dilatometer.The experimental results show that homogeneous microstructure without film-like ferrites and chain-like precipitates at grain boundary can be obtained through surface intensive cooling and transverse cracks do not occur on the slab surface.For the ex-perimental steel, fine ferrite can form at slab surface when the water flow rate is larger than 1560 L/min at vertical section.As the distance to surface increases, microstructure turned to ferrite and pearlite. Moreover, nano-size carbonitrides precipitated in the ferrite grain and the size was larger at the junc-tion of the dislocations.The mechanical experiment results show that the hot ductility of the sample deformed at 650℃ was better than that of the sample deformed at 750℃.The reason is that film-like ferrite formed at the grain boundary in the sample deformed at 750℃.Thus, the slab must be cooled quickly below A r3 to prevent the occurrence of film-like ferrite and transverse cracks on the slab surface during casting. 相似文献