Stability of the Dividing Distribution Function Method for ParticleSize Distribution Analysis in Small Angle X－Ray Scattering

ＳｔａｂｉｌｉｔｙｏｆｔｈｅＤｉｖｉｄｉｎｇＤｉｓｔｒｉｂｕｔｉｏｎＦｕｎｃｔｉｏｎＭｅｔｈｏｄｆｏｒＰａｒｔｉｃｌｅＳｉｚｅＤｉｓｔｒｉｂｕｔｉｏｎＡｎａｌｙｓｉｓｉｎＳｍａｌｌＡｎｇｌｅＸ－ＲａｙＳｃａｔｔｅｒｉｎｇＧａｎｇＪｉｎｙｕａｎ；Ｌｉｕ...     

Influence of CeO_2 on Corrosion Resistance of Laser Alloyed M_（80）S_（20） Alloy Layer

ＩｎｆｌｕｅｎｃｅｏｆＣｅＯ_２ｏｎＣｏｒｒｏｓｉｏｎＲｅｓｉｓｔａｎｃｅｏｆＬａｓｅｒＡｌｌｏｙｅｄＭ_（８０）Ｓ_（２０）ＡｌｌｏｙＬａｙｅｒ￥ＳｕＭｅｉ；ＣｈｅｎＣｈｉｎａｎ；ＷａｎｇＹｏｕ；ＬｉＤｉ；ＺｈｕＬｉｑｕｎ（ＭａｔｅｒｉａｌｓＳｃｉｅ?..     

Effect of Rare Earth Metals on Microstructure of Directional Solidified Al－3Li Alloy

ＥｆｆｅｃｔｏｆＲａｒｅＥａｒｔｈＭｅｔａｌｓｏｎＭｉｃｒｏｓｔｒｕｃｔｕｒｅｏｆＤｉｒｅｃｔｉｏｎａｌＳｏｌｉｄｉｆｉｅｄＡｌ－３ＬｉＡｌｌｏｙ￥ＷａｎｇＬｉ－Ｍｉｎ；ＤａｎｇＰｉｎｇ；ＤｕＦｕ－Ｙｉｎｇ；ＺｈａｏＭｉｎ－Ｓｈｏｕ（Ｃｈａｎｇｃｈｕ...     

Synthesis of Y_2O_2S：Eu~（3＋） Phosphor by Microwave Thermal Effectand Its Luminescent Properties

ＳｙｎｔｈｅｓｉｓｏｆＹ_２Ｏ_２Ｓ：Ｅｕ~（３＋）ＰｈｏｓｐｈｏｒｂｙＭｉｃｒｏｗａｖｅＴｈｅｒｍａｌＥｆｆｅｃｔａｎｄＩｔｓＬｕｍｉｎｅｓｃｅｎｔＰｒｏｐｅｒｔｉｅｓＬｉＹｕａｎｙｉｎｇ（李沅英）；ＣａｉＳｈａｏｈｕａ（蔡少华）；ＤａｉＤｅｃｈａｎ?..     

Development of Microalloyed Medium-Carbon Steel with Improved Toughness

ＤｅｖｅｌｏｐｍｅｎｔｏｆＭｉｃｒｏａｌｌｏｙｅｄＭｅｄｉｕｍ－Ｃａｒｂｏｎ　ＳｔｅｅｌｗｉｔｈＩｍｐｒｏｖｅｄＴｏｕｇｈｎｅｓｓＷａｎｇＱｉ；ＬｉＧｕｉｆｅｎ；ＤｏｎｇＨａｎＡｂｓｔｒａｃｔ：Ｔｈｅａｐｐｌｉｃａｔｉｏｎｏｆｔｈｅｈｏｔ－ｒｏｌｌｅ...     

Effect of CeCl_3 on the Photosynthetic Characteristics of Spirulina Platensis

ＥｆｆｅｃｔｏｆＣｅＣｌ_３ｏｎｔｈｅＰｈｏｔｏｓｙｎｔｈｅｔｉｃＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＳｐｉｒｕｌｉｎａＰｌａｔｅｎｓｉｓ￥ＣｈｕＺｈｏｎｇ－Ｘｉ；ＭｕＭｅｎｇ－Ｈｕａ；ＺｈａｎｇＨｅ－Ｍｉｎ；ＧａｏＤｅ－Ｌｕ；ＷｕＺｈａｏ－Ｍｉｎｇ（?..     

Scanning Analysis of REE in Bastnaesite with Synchrotron Radiation X－Ray Fluorescence Microprobe

ＳｃａｎｎｉｎｇＡｎａｌｙｓｉｓｏｆＲＥＥｉｎＢａｓｔｎａｅｓｉｔｅｗｉｔｈＳｙｎｃｈｒｏｔｒｏｎＲａｄｉａｔｉｏｎＸ－ＲａｙＦｌｕｏｒｅｓｃｅｎｃｅＭｉｃｒｏｐｒｏｂｅＡｎＱｉｎｇｘｉａｎｇ（安庆骧）；ＷａｎｇＲｕｉｂｉｎｇ（王锐兵）；ＤｅｎｇＳａ...     

Studies of Characterization of Microstructures for Low Dimensional Materials

ＳｔｕｄｉｅｓｏｆＣｈａｒａｃｔｅｒｉｚａｔｉｏｎｏｆＭｉｃｒｏｓｔｒｕｃｔｕｒｅｓｆｏｒＬｏｗＤｉｍｅｎｓｉｏｎａｌＭａｔｅｒｉａｌｓＺＨＵＪｉｎｇ；ＬＩＭＸｉＷｅｉ；ＸＵＨａｉＧａｎｇ；ＨＵＪｉｎＳｈｅｎｇ；ＬＵＨｏｎｇＸｉｕ；ＧｕｏＷｅｉ；ＺＨ...     

Modification of Corrosion Resistance by Yttrium IonImplantation of 304L Stainlesa Steel

ＭｏｄｉｆｉｃａｔｉｏｎｏｆＣｏｒｒｏｓｉｏｎＲｅｓｉｓｔａｎｃｅｂｙＹｔｔｒｉｕｍＩｏｎＩｍｐｌａｎｔａｔｉｏｎｏｆ３０４ＬＳｔａｉｎｌｅｓａＳｔｅｅｌＷｅｎｇＤｕａｎ（翁端）；ＷａｎｇＭｉｎ（王敏）；ＣｈｅｎＪｉａｆｕ（陈家福）；ＨｕｏＳｈｉｚｈ...     

Synthesis and Structure Determination of Yttrium Alkoxides and Alkoxy Yttrium Monomers with Double Bond

ＳｙｎｔｈｅｓｉｓａｎｄＳｔｒｕｃｔｕｒｅＤｅｔｅｒｍｉｎａｔｉｏｎｏｆＹｔｔｒｉｕｍＡｌｋｏｘｉｄｅｓａｎｄＡｌｋｏｘｙＹｔｔｒｉｕｍＭｏｎｏｍｅｒｓｗｉｔｈＤｏｕｂｌｅＢｏｎｄ￥ＳｈｅｎｇＹｕ；ＣｈｅｎＬｉｙｏｎｇ；ＺｈａｎｇＷｅｎｇｏｎｇ（Ｔｈ...     

M2高速钢铸带组织特征及其后续处理

研究了M2高速钢在不同制备条件下的凝固组织特征以及工业铸带中碳化物在高温热处理、热变形作用下的变化,测量了在不同制备条件下高速钢的凝固速度和共晶碳化物网的厚度,采用透射电镜研究了后续高温热处理、热变形对工业铸带中碳化物相的影响,采用定量金相法分析了制备条件和后续处理工艺对铸带组织的影响.研究结果表明,双辊薄带连铸工艺可以细化高速钢凝固组织的枝晶和共晶碳化物网的厚度,改善碳化物的分布,后续高温热处理和热变形可以进一步优化工业铸带中的碳化物组织.建议在工业铸带的后续处理中同时采用高温热处理和热变形工艺以改善铸带组织.     

Structure of a Carbon Steel–Stainless Steel Bimetal

Bimetallic samples may be produced by casting St3 structural steel between sheets of Kh18N9T stainless steel in a mold, with subsequent hot rolling of the three-layer sheet. Such samples have a structure in which Kh18N9T stainless steel appears at the outer edge on both sides, while the core consists of St3 structural steel. Analysis of the boundary between the steels confirms the absence of defects: it is continuous and of high quality. The microstructure of the junction is investigated by optical, scanning-probe, and electron microscopy. Three structural components are observed from the pearlitic to the austenitic steel: a weakened section of the ferritic layer; a strengthened section of the ferritic layer; and a dark-etching layer at the austenitic steel. The following results are obtained by scanning-probe microscopy—in particular, the constantforce contact method—and optical metallography: on approaching the boundary from the St3 steel, a carbon- free layer with purely ferritic structure is observed, rather than the usual structure for low-carbon steel, which consists of a ferrite matrix with pearlite colonies. On approaching the boundary from the Kh18N9T steel, a carburized layer is observed. In addition, the boundary includes an intermediate carbide layer (depth up to 50 μm). The change in microhardness in the region where the St3 structural steel meets the external layer of Kh18N9T stainless steel indicates considerable increase in strength of the materials. Elemental microanalysis of the St3 steel–Kh18N9T steel boundary reveals the change in concentration of the alloying elements on approaching the boundary. The presence of chromium in St3 steel and the increase in carbon concentration in Kh18N9T stainless steel confirm that two opposing diffusional fluxes are formed: the diffusion of carbon from the St3 steel; and the diffusion of alloying elements from Kh18N9T steel. The resulting carbides explain the increased hardness of both steels close to the boundary.     

Combinatorial Alloy Design by Laser Additive Manufacturing

The authors uses laser additive manufacturing (LAM) as a combinatorial method for synthesizing microstructurally and compositionally piecewise graded bulk alloys. Authors fabricate blocks consisting of a sequence of ≈500 μm thick tool steel layers, each with different chemical composition, by laser metal deposition where alloy powders are deposited layer‐wise on a substrate. The reference materials are a Cr–Mo–V hot working tool steel and a Ni‐based maraging steel. The layers between them consist of corresponding blends of the two materials with varying composition from layer to layer (alloy volume fractions 80:20, 60:40, 40:60, and 20:80). The bulk alloy is hot rolled and heat treated. Subsequently each layer is characterized for microstructure, chemical composition and mechanical properties using electron back scatter diffraction, tensile testing, and indentation. The approach is an efficient high‐throughput method enabling rapid probing of novel compositional alloy blends. It can be applied for finding new alloys both, by LAM and for LAM. For the tool steel blends synthesized here, authors observe that the Cr–Mo–V tool steel, when mixed with the Ni‐base maraging steel, can be continuously tuned for a strength‐ductility profile in the range of 800–1650 MPa strength and 15–25% tensile elongation.     

THE PREPARATION OF CARBIDE-ENRICHED TOOL STEELS BY POWDER METALLURGY

Abstract

Two PM methods of increasing the carbide content of M2 high-speed steel have been investigated: (1) By the mechanical mixing of tool-steel powder with up to 15 wt.-% of either VC or TiC powders of two different size ranges. (2) By the production of fully prealloyed carbide-enriched powders by gas atomization.

The mixed powders were consolidated by either cold isostatic pressing or explosive compaction, and then vacuum-sintered. Fully dense specimens, however, could be obtained only by subsequent hot working. The pre alloyed powders could not be cold compacted and were densified by hot working the canned loose powders.

With the mixed powders, the carbide dispersion depended closely both on the relative sizes and amounts of the tool-steel and carbide particles and onthe total reduction during hot working. With the fully prealloyed powders a very fine uniform carbide dispersion was obtained in all samples. It was found that with proper composition control the new materials could be heat-treated in a manner similar to that applied to M2 tool steel; significant increases were thus obtained in hardness and wear-resistance. The preferred production methods would be to employ mixed powders for TiC-enriched materials and fully pre alloyed powders for VC-enriched materials.     

Challenge to control mould heat transfer during thin slab casting

Abstract

At the thin slab caster of Tata Steel, IJmuiden, mild cooling mould powders were introduced with the aim to control the mould heat transfer during casting. These mild cooling mould powders are characterised by specific values of basicity, solidification point and chemical composition. Application of these mould powders resulted in a redistribution of mould heat transfer during casting, i.e. a reduced and more stable mould heat transfer in the critical upper part of the mould and an increased mould heat transfer in the lower part of the mould. The average mould heat transfer and hence the shell thickness at mould exit are comparable to the standard powder. The application of mild cooling mould powders also resulted in improved solidification behaviour of the steel shell. A thinner chill zone with smaller thickness variations was observed. Furthermore, it was found that the mould taper required optimisation to match the changes in shrinkage behaviour to ensure uniform solidification. The use of mild cooling powders was observed to give an increase in mould friction. Mould thermal monitoring indicated that the solid slag films fractured (sheeting) in the upper part of the mould. However, no operational problems were reported, which indicate that the first 200 mm under the steel meniscus is essential for initial solidification and for the formation of a homogeneous steel shell. All these findings can be understood by considering the crystallisation properties of the mould slag, which include the cooling rate. Mild cooling has been shown to provide uniform heat transfer and adequate lubrication for high speed thin slab casting.     

喷射成形高速钢T15喷余粉末的研究

本文是对喷射成形T15合金喷余粉末的组织和性能进行分析和研究,结果表明:T15喷余粉末的氧含量低,大部分粉末呈球形,表面较光滑;粉末表面和内部为胞晶组织,析出的碳化物尺寸细小,基本在0.5μm以下,主要为富钒的MC型碳化物和M2C型碳化物.T15喷余粉末粒度呈对数正态分布,并且具有良好的流动性、较高的松装密度和振实密度,粉末填充性和均匀性较好,有利于粉末包套和热等静压工艺的进行.     

奥氏体不锈钢15Mn-22Cr-0.56N的热塑性和轧制工艺对其性能的影响

通过热模拟试验和20%～60%单道次变形的热轧试验研究了奥氏体不锈钢15Mn-22Cr-0.56N的高温拉伸和压缩塑性以及热轧工艺对组织和机械性能的影响。模拟试验结果表明,该钢最佳热塑性区为1000～1150℃;热轧试验结果表明,15Mn-22Cr-0.56N钢最佳轧制工艺参数为1000～1050℃、40%变形可得到较高的强韧性。     

超声波作用下不同添加剂对高碳钢凝固组织的影响

 主要研究了在超声波作用下不同添加剂对高碳钢凝固组织的影响。结果表明：在超声波作用下,高碳钢液中添加钛铁、铈可以明显细化其凝固组织,但是添加铝对其凝固组织的细化作用不明显。高碳钢凝固组织的细化是由于Ti（C,N）可以作为非均质形核的核心,促进高碳钢液凝固过程的形核,Ti（C,N）有效的钉扎晶界作用,阻止初生奥氏体晶粒的长大;超声空化作用下稀土氧化物、氧硫化物数量的增多,增加了高碳钢液凝固过程中非均质形核核心的数量。     

Structure and mechanical properties of a nonmagnetic high-nitrogen corrosion-resistant 05Kh22AG15N8M2F cast steel produced by high-gradient directional solidification

The structure and properties of an austenitic high-nitrogen corrosion-resistant 05Kh22AG15N8M2F cast steel produced by high-gradient directional solidification (HGDS) and equiaxed-grain solidification (ES) have been studied and compared. In contrast to ES, HGDS allows one to substantially decrease the degree of dendritic segregation of alloying elements, to eliminate porosity, and to increase the strength and plasticity of the steel.     

Structure and Properties of Heat-Resistant Steels Obtained from Powders after Mechanical Activation

The effect of mechanical activation of heat-resistant steel 55Kh20N4AG9 powders on the structure and properties of high-density material obtained by dynamic hot pressing with extrusion elements was investigated. Mechanical activation improves the chemical homogeneity of the highly alloyed material, decreases the particle size of the strengthening carbonitride phase, promotes its interaction with dislocation tangles and increases their thermal stability. Mechanical activation of powders with intermediate anneals promotes the accumulation of thermally stable defects in the crystal structure and leads to the accelerated formation of a cellular fragmented structure in the austenite, characterized by a high dislocation density in block walls. The developed cellular fragmented substructure is retained after dynamic hot pressing and subsequent heat treatment, and elevates the mechanical properties of the high-density heat-resistant powder metallurgy steels.