低碳低硅合金钢盘条氧化铁皮微观结构的电子显微学研究

采用EDS和XRD等技术研究了吐丝温度为950 、980 ℃时低碳低硅钢盘条氧化铁皮的显微结构特征及组成相。采用EBSD技术研究了低碳低硅合金钢盘条氧化铁皮的微观结构。实验结果表明：盘条的氧化铁皮结构主要有3层,最内层为FeO,中间层为Fe3O4,而最外层为Fe2O3,且FeO层最厚。吐丝温度对氧化皮厚度有显著影响,吐丝温度较高的情况下氧化皮较厚且结构疏松,有利于机械剥离。盘条氧化铁皮FeO层晶粒尺寸小于Fe基体的晶粒尺寸。盘条氧化铁皮中的FeO相比例最高,相比例与氧化铁皮各层的厚度关系一致,其中吐丝温度较低的实验钢中FeO比例较小,Fe3O4和Fe2O3比例较高。     

温度对氢气还原热轧碳钢表面氧化皮的影响

热轧碳钢BRC3表面氧化皮由最外Fe2O3层、中间fe3O4层及最内FeO层组成,Fe3O4层与FeO层的厚度比约1:3.在氧化皮的加热过程中,加热温度低于500℃,氧化皮的成分及结构保持不变;加热温度升高至600℃,FeO层内有大量Fe3O4析出;加热温度为700℃,氧化皮中只存在单一的FeO层.在氢还原过程中,还原温度为400℃时,仅有表层很小一部分氧化皮被还原,当还原温度为500℃时,氧化皮完全被还原为金属铁;但当还原温度升高至600及700℃时,还原效果反而略有下降.     

热轧板的氧化皮结构对酸洗效果的影响

采用金相显微镜和背散射电子衍射（EBSD）技术，从氧化皮结构出发，对低碳钢热轧板氧化皮的结构与热轧板酸洗效果之间的关系进行了研究。结果表明，低碳钢热轧板在卷取前期（温度在400～500℃）的氧化铁皮分为两层，即外层是Fe3O4，内层为FeO；在室温下放置两天以后的板，氧化皮中的FeO完全分解为Fe3O4和Fe，并且铁颗粒在原FeO的晶界富集。具有FeO和Fe3O4复合结构的氧化皮比Fe3O4单层氧化皮更易酸洗。     

温度对高碳钢线材氧化铁皮厚度和结构的影响

应用5种不同的热处理工艺研究高碳钢线材氧化铁皮在高温下的氧化机制,对热处理后的5个试样表面的氧化铁皮进行SEM观察。研究了高碳钢线材在氧化过程中,温度对氧化铁皮厚度的影响规律和氧化铁皮先共析反应温度。结果表明,在高温氧化时,随温度的升高,氧化铁皮厚度随之增加,在850℃以上时,其氧化速率急剧增加;氧化铁皮从高温冷却到700℃时,FeO处于不稳定状态,析出单相Fe3O4,减少了下一步要发生共析反应的FeO的量,从而降低了共析组织α-Fe+Fe3O4在整个氧化铁皮中所占比率。     

Fe- 0.6Si合金表面氧化铁皮空气条件下等温转变行为的研究

采用管式电阻加热炉,对Fe- 0.6Si合金在不同温度下表面生成的氧化铁皮的等温转变行为进行了研究。结果表明：氧化铁皮为4层分层结构,由外向内依次为较薄的Fe2O3层,Fe3O4层,较厚的FeO层和Fe2SiO4层。在等温氧化过程中,由于受离子浓度和体系中自由能以及过冷度的影响,氧化铁皮在400、450 、500 ℃等温转变时,在金相检测中可以发现先共析Fe3O4相,没有出现共析产物;在550～650 ℃之间没有出现先共析组织和共析组织。     

卷取温度对510L钢氧化皮结构的影响

利用模拟法研究了热轧卷曲温度对汽车大梁钢510L氧化皮结构的影响.结果表明,精轧后的510L钢表面氧化皮主要由FeO层和少量Fe3O4层组成;在不同的卷取温度下,FeO层发生不同程度的共析反应,最终形成不同结构的表面氧化皮;在450～550℃时,FeO层共析反应发生的速度最快,形成的最终氧化皮中Fe3O4含量也最多.     

热轧工艺参数和供氧差异对氧化铁皮结构和厚度的影响

对比了510L热轧钢在两种热轧工艺条件下钢板表面氧化铁皮的结构和厚度的演变规律。结果表明:在两种热轧工艺条件下,钢卷均是边部的氧化铁皮厚度最大,1/4处的次之,心部的厚度最小。由于外界供氧差异,使得钢板沿宽度方向,边部的氧化铁皮层中原始的Fe3O4较厚,并且FeO层的共析转变较为完全。1/4处原始的Fe3O4较薄,部分FeO发生共析转变。中心处没有原始的Fe3O4,只有少量的FeO发生转变。适当地降低精轧开轧温度和卷取温度,提高终轧温度能减小氧化铁皮厚度,促进FeO发生共析转变。     

三氯化钛在酸液中的试验应用

1酸洗概况 目前钢制保持架仍采用盐酸酸洗,其目的是洗去氧化铁皮、锈及絮毛刺.钢板表面的氧化铁皮,一般是由三层组成,外层是三氧化二铁(Fe2O3),中间层是四氧化三铁(Fe3O4),内层是氧化亚铁和四氧化三铁(FeO+Fe3O4).氧化铁皮有很多微观裂纹和孔隙,特别是内层比较疏松,因此,当钢板表面被酸液浸蚀后,酸液就通过氧化铁皮中的裂缝、孔隙、渗入钢板基体起化学反应.     

SPHC钢高温空气氧化动力学的研究

采用热重法研究了SPHC钢在500～1050℃之间的高温空气氧化动力学.通过扫描电镜对氧化层的形貌和厚度进行了观察,利用X射线衍射仪和激光拉曼光谱仪对氧化层进行了相结构分析.结果表明:SPHC的高温空气氧化动力学曲线符合抛物线规律.570℃以下氧化时,氧化层主要由Fe3O4和Fe2O3组成;570～80HD℃之间氧化时,氧化层由极薄的Fe2O3外层,Fe3O4中间层和靠近基体的FeO组成,FeO层厚度占整个氧化层的90%以上;900℃氧化时,FeO层中出现许多颗粒状的Fe3O4小颗粒.     

热轧板卷红色氧化铁皮的成因及对策

红色氧化铁皮是热轧板卷比较常见的问题,对于含硅钢尤为突出。其根源就是Fe充分氧化成Fe2O3的结果。在高温状态下,热轧板卷表面应该形成FeO或者FeO与Fe3O4的混合体。若除鳞不尽,会导致FeO的压入,并在后续过程中,进一步氧化成Fe2O3,最终形成红色氧化铁皮。轧辊的剥落也是形成弥散状氧化铁皮的原因。对于含硅钢,在与普通钢种采取减少在炉时间,增加粗除鳞机压力,定期检查水嘴,增加粗轧间除鳞道次,开启轧辊防剥落水,控制轧制温度等消除氧化铁皮措施的前提下,提高出炉温度,使粗除鳞时表面温度不低于FeSiO4的熔点温度(1173℃),是减少红色氧化铁皮的最佳途径。内容导读     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.