共查询到20条相似文献,搜索用时 125 毫秒
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JFE开发出两种高加工性的高碳钢板.各向同性高碳冷轧板的r值各向异性(Δr)降到了0.06,并且具有良好的成形性和低温短时加热淬透性,用于传动部件的钢板成形时可避免尺寸精度下降.高扩孔性热轧高碳钢板(SC)采用热轧后的超急速冷却使碳化物弥散分布,具有良好的冲孔性和扩孔性,适用于增厚加工. 相似文献
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为获得完全球化的超高碳钢组织,基于离异共析转变机制对2%铝质量分数超高碳钢进行球化退火工艺研究。研究发现,由于成分的不均匀性,超高碳钢锻态组织由片层间距不一致的珠光体和网状碳化物组成,单纯使用离异共析工艺无法使其完全球化;2%铝质量分数超高碳钢锻态组织网状碳化物厚度在1 μm以下,[Acm]温度以下正火即可获得片层均匀细小的珠光体并消除网状碳化物;提高正火温度能显著减少正火组织中长条和短棒状碳化物的数量,利于获得较好的球化组织。2%铝质量分数超高碳钢经900~925 ℃正火后在830 ℃奥氏体化并在760 ℃等温4 h后获得了由超细铁素体+细小球状渗碳体组成的完全球化组织。 相似文献
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Matthew D. Hecht Bryan A. Webler Yoosuf N. Picard 《Metallurgical and Materials Transactions A》2018,49(6):2161-2172
In this study, two different melting methods were used to investigate effects of Nb modification on microstructure in ultrahigh carbon steel (UHCS). Nb-free and Nb-modified UHCS samples were produced by melting and resolidifying an industrially produced base UHCS with and without addition of Nb powder. Microstructure was characterized using scanning electron microscopy, X-ray diffraction, and electron dispersive spectroscopy. Equilibrium computations of phase fractions and compositions were utilized to help describe microstructural changes caused by the Nb additions. Nb combined with C to form NbC structures before and during austenite solidification, reducing the effective amount of carbon available for the other phases. Cementite network spacing in the Nb-free samples was controlled by the cooling rate during solidification (faster cooling led to a more refined network). Network spacing in the Nb-modified UHCS could be enlarged by NbC structures that formed cooperatively with austenite. 相似文献
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合金化和球化工艺对超高碳钢组织和性能的影响 总被引:1,自引:0,他引:1
研究了合金化和球化工艺对超高碳钢组织和性能的影响。用扫描电子显微镜、透射电子显微镜和能谱仪观察了钢的组织形貌和元素分布。结果表明:在碳和铬含量相同的超高碳钢中加入同量的合金元素铝和硅时,铝可明显抑制锻造组织中网状或粗大的颗粒状碳化物的析出、细化珠光体组织和控制石墨形成。UHCS 213Si和UHCS 261Al钢经850 ℃×3 h球化退火处理后,都能得到较好的球化组织,其力学性能分别为:UHCS 213Si钢,Rm=1 033 MPa,Re=734 MPa,A=149%;UHCS 261Al钢,Rm=973 MPa,Re=677 MPa,A=182%。 相似文献
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A new spheroidizing process of ultra-high carbon steel (UHCS) containing C 1.55%, Cr 1.45%, and Al 1.5% in mass percent has been proposed. The effect of processing parameters on the microstructure was analyzed. The UHCS produced by this new process has a microstructure with recrystallized ferrite matrix and fine and uniform carbide particles. After this spheroidizing, the UHCS exhibits good mechanical properties at ambient temperature, for example σb= 1 100 MPa, σs =915 MPa, δ=8% and high ratio of σs/σb. 相似文献
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通过喷射成形和传统熔炼(中频冶炼+电渣重熔)两种工艺生产了高速钢M2(W6Mo5Cr4V2)试样,利用金相显微镜和M-200磨损试验机对同规格同位置的两种试样的退火组织、非金属夹杂物、淬回火硬度、显微组织和力学性能进行了研究。结果表明,喷射成形M2试样的碳化物分布均匀、尺寸细小,传统熔炼M2试样碳化物呈条带状分布;在相同热处理制度和位置下,喷射成形M2试样的回火硬度与传统熔炼M2试样相当;喷射成形M2试样的耐磨性要比传统M2试样提高约41%;喷射成形M2试样中尺寸大于2μm的MC类碳化物数量明显多于传统M2试样,使得在同等硬度下喷射成形M2试样的耐磨性能要优于传统M2试样。由此可知,喷射成形M2试样的组织及力学性能均优于传统熔炼M2试样,喷射成形技术具有工艺先进性。 相似文献
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M. Ramadan 《Transactions of the Indian Institute of Metals》2012,65(5):479-483
The microstructure of 1.4?% carbon steel produced either by ordinary casting or semi-solid casting with different primary fraction of solids using cooling plate technique was investigated. The microstructure of ordinary ultrahigh-carbon steel (O-UHCS), was improved by the semi-solid processing. Grain boundary cementite thickness of UHCS and its morphology is affected by semi-solid process. Grain boundary cementite thickness of about 2???m can be achieved by pouring the semi-solid slurry with 0.31 fraction of solid. The pearlitic interlamellar spacing of semi-solid processed UHCS is shorter compared to O-UHCS. 相似文献
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C. K. Syn D. R. Lesuer J. Wolfenstine O. D. Sherby 《Metallurgical and Materials Transactions A》1993,24(7):1647-1653
Laminated metal composites containing equal volume percentage of ultrahigh carbon steel (UHCS) and brass were prepared in
three different layer thicknesses (750, 200, and 50 μm) by press- bonding and rolling at elevated temperature and were tensile
tested at ambient temperature. A dramatic increase in tensile ductility (from 13 to 21 to 60 pct) and a decrease in delamination
tendency at the UHCS-brass interfaces were observed as the layer thickness was decreased. The layer thickness effect on ductility
is attributed to residual stress whose influence on delamination is decreased as the layer thickness is decreased. Suppression
of delamination inhibits neck for- mation in the UHCS layers, allowing for extended uniform plasticity. For a given layer
thick- ness, the tensile ductility decreases as the ratio of hardness of component layers is increased. 相似文献
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C. Banjongprasert S. C. Hogg E. Liotti C. A. Kirk S. P. Thompson J. Mi P. S. Grant 《Metallurgical and Materials Transactions A》2010,41(12):3208-3215
An Al-2.7Fe-1.9Cr-1.8Ti alloy has been spray formed in bulk and the microstructure and properties compared with those of similar alloys produced by casting, powder aomization (PA), and mechanical alloying (MA) routes. In PA and MA routes, a nanoscale metastable icosahedral phase is usually formed and is known to confer high tensile strength. Unlike previous studies of the spray forming of similar Al-based metastable phase containing alloys that were restricted to small billets with high porosity, standard spray forming conditions were used here to produce a ~98 pct dense 19-kg billet that was hot isostatically pressed (“HIPed”), forged, and/or extruded. The microstructure has been investigated at all stages of processing using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and synchrotron X-ray diffraction (XRD) at the Diamond Light Source. Consistent with the relatively low cooling rate in spray forming under standard conditions, the microstructure showed no compelling evidence for the formation of metastable icosahedral phases. Nonetheless, after downstream processing, the spray-formed mechanical properties as a function of temperature were very similar to both PA rapid solidification (RS) materials and those made by MA. These aspects have been rationalized in terms of the typical phases, defects, and residual strains produced in each process route. 相似文献
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Superplastic forming offers a promising approach for reducing the cost of high-performance metal components with complex shapes.
Severe thermomechanical deformation is one method for producing the fine grain structure needed to permit superplastic forming
economically. Our approach to generating fine-grained microstructures is by cyclic heat treatment of rapidly solidified material.
First, a metastable structure is produced by rapid quenching of the liquid metal. Then, solid-state phase transformations
at modest temperatures are employed to refine this structure. In the ultra-high-carbon steels (UHCS) studied, the brittle
as-cast structure of martensite and austenite was transformed, after cyclic heat treatment, to a ductile mixture of 1-μm ferrite and 0.25-μm carbide. Varying the heat-treat temperatures by 100 °C within the transformation range had little effect on the scale of
the microstructure. Higher C resulted in coarser carbide spheroids, addition of Al refined the microstructure, and the finest
mean carbide size was obtained with an intermediate level (5 pct) of Cr. Refinement of the martensite plates retained austenite
via cyclic tempering and austenitization was found to be the key step in the overall mechanism for phase transformation-induced
grain refinement in rapidly solidified UHCS. 相似文献
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The superplastic behaviour of ultrahigh carbon steels (UHCS) has been greatly improved by silicon additions and thermomechanical processing. A UHC steel containing 3 wt% Si shows superplastic behaviour in a wide temperature range from 650 to 900°C. This behaviour is observed even at high strain rates, i.e. 10‐2 s‐1, in the temperature range between 800 and 825°C. Furthermore, the flow stress required for superplastic deformation is reduced drastically, i.e. σ=12 MPa at a strain rate of 10‐4 s‐l. Finally, it is found that the flow stress at a given strain rate is relatively constant over a wide range of temperatures (750‐900°C) due to a unique transformation behaviour in the UHCS‐3Si alloy. 相似文献