Texture comparison of an ordinary IF steel and a high-strength IF steel under ferritic rolling and high-temperature coiling

The present work was performed to investigate the texture difference of an ordinary Ti-IF steel and a high-strength Ti-IF steel under ferritic hot rolling and high-temperature coiling. Comparing with the completely recrystallized textures of the ordinary IF steel, the textures of the high-strength IF steel were still deformed textures. The texture difference for the two steels is related to high P content in the high-strength IF steel which prevents the recrystallization during the coiling process. For the ordinary IF steel, the texture components were mainly very weak {001}110 orientation at the surface, and partial 110//RD (rolling direction) textures focused on {223}110 orientation and 111/ND (normal direction) texture at the mid-section and 1/4-section. For the high-strength IF steel, the texture components were mainly of {110}001 orientation at the surface and of a sharp 110//RD texture from {001}110 to {223}110 and weak 111/ND texture at the mid-section and 1/4-section.     

太阳能电池光谱响应度测量方法的分析与比较

介绍太阳能电池光谱响应度的两种测量方法,即滤色片法和单色仪法,分析和比较其优缺点,并用这两种方法,对不同类型的太阳能电池(单晶硅和多晶硅)进行测量。结果表明,单色仪法能够反映该位置处太阳能电池的光谱响应特性;滤色片法更能准确反映出整块太阳能电池的光谱响应特性。光谱响应度的准确计量是实现太阳能量值传递和比对的关键技术。     

Assessment of manual assembly complexity: a theoretical and empirical comparison of two methods

There are several theoretical methods for assessment of assembly complexity but there are few practically applicable methods. One of the methods, CompleXity Index (CXI), aims at assessing operators’ perception of manual assembly complexity in running production. Another recently developed method, Basic Assembly Complexity (CXB) is intended for predictive assessment of basic manual assembly complexity in early product and production development. Both CXI and CXB aim to improve assembly conditions for operators, reduce assembly-related errors and the costs for corrective measures as well as increase assembly quality although in different ways and at different organisational levels and life cycle stages. The purpose of this study was to compare the two methods to obtain feedback and learn from operators experience in order to develop better predictive assessment criteria. The method comparison showed that about 50% of the CXB assessment approaches were similar to CXI but other covered different aspects. In comparison of the complexity values of the methods no significant results were obtained. However, some CXI issues that were not taken into account in CXB should be considered. CXB and CXI could be used in conjunction but further assessment criteria are probably needed.     

Non-contact stress measurement in granular materials via neutron and X-ray diffraction: theoretical foundations

Model validation remains a serious problem within the field of computational granular materials research. In all cases the rigor of the validation process is entirely dependent on the quality and depth of the experimental data that forms the point of comparison. Neutron and X-ray diffraction methods offer the only quantitative non-contact method for determining the spatially resolved triaxial stress field within granular materials under load. Measurements such as this can provide an unprecedented level of detail that will be invaluable in validating many models. In this paper the theoretical foundation underpinning diffraction-based strain measurements, their conversion to local stress in the particles and ultimately into the bulk stress field is developed. Effects such as elastic anisotropy within the particles of the granular material, particle plasticity and locally inhomogeneous stress distribution are shown to not offer any obstacles to the method and a detailed treatment of the calculation of the bulk stresses from the particle stresses is given.     

Nosing of thin-walled hollow spheres using a die: experimental and theoretical investigation

In contrast to end forming of tubes, there is no published work that addresses the manufacturing of thin-walled hollow spheres by nosing using a die. Important characteristics of the process such as the development of plastic instability modes (local buckling), thickening of the tube-wall and occurrence of wrinkling needs to be properly studied. This paper presents a numerical and experimental investigation of the nosing of thin-walled hollow spheres using a die with the purpose of examining the process mechanics, obtaining a better understanding of the modes of deformation and establishing the formability limits in terms of the major process parameters. The paper also presents a new concept of nosing thin-walled hollow spheres that makes use of preforming stages and tube-end preparation schemes in order to successfully extend the formability limits of the process. Theoretical investigation and process development are supported by numerical predictions based on the finite element flow formulation and the overall methodology is assessed by means of experimental tests on industrial AA6060 Aluminium alloy tubes (natural aged) under laboratory-controlled conditions.     

Patient satisfaction measurement strategies: a comparison of phone and mail methods.

BACKGROUND: In 1998 the BJC Health System (St Louis) made the decision to migrate its patient satisfaction measurement system from a mail-out/mail-back method to a phone interview method. Out of concern that results obtained by phone would not be comparable with the 4 years of mail-based data, a controlled study was undertaken to directly compare mail and phone responses and to evaluate response rates, patient sample demographics, and patient satisfaction ratings. METHODS: Mail and phone responses obtained from parallel random samples selected from inpatient, outpatient test/treatment, outpatient surgery, and emergency service patient populations were compared. Patients were randomly selected to receive a standardized satisfaction survey by either phone or mail 10 to 14 days postdischarge. RESULTS: Significantly higher response rates were obtained by telephone then via the mail-based method for all four samples. After adjusting for demographic differences, numerous significant differences in mean scores as well as percentages of excellent and fair or poor responses were observed, and more positive ratings were obtained by phone. DISCUSSION: Crude comparisons of satisfaction scores between organizations using phone and mail-based responses may lead to erroneous conclusions about consumer-perceived quality. Organizations that use mixed-mode surveys should conduct careful side-by-side studies of the methods used on the survey of interest and then establish a correction formula to adjust the results for the measurement biases.     

Residual stress fields in surface-treated silicon carbide for space industry—comparison of biaxial and triaxial analysis using different X-ray methods

Any mechanical surface treatment and machining leaves ‘footprints’ in the form of residual stress fields in the surface region of technical parts or components, which are detectable by X-ray diffraction. In the present paper, we applied different X-ray methods to investigate the residual stress state in the near-surface zone of sintered silicon carbide after mechanical surface processing. Using the sin² ψ-based ‘universal plot’ method, we found steep gradients for the in-plane components σ₁₁ and σ₂₂ in the form of high compressive stresses at the surface, which change into tensile stresses within a few microns. To gain information on the triaxial residual stress state, we applied the scattering vector method, which is based on strain depth profiling by sample rotation around the diffraction vector. For the in-plane stresses, we observed gradients similar to those obtained by the ‘universal plot’ method, but they were shifted on the absolute scale towards tensile stress. We explain this difference by ‘pseudo-macroscopic’ tensile residual stress fields σ₃₃, which act normal to the surface and therefore pretend higher in-plane compressive stresses σ_ii (i = 1, 2), if they are not regarded in the evaluation procedure.     

A comparison of theoretical and experimental methods of calibrating the electrical potential drop technique for crack length determination

The calibration of the do pd technique for determining crack length in compact tension, corner notched and fin cracked test pieces is described. Good agreement is shown between finite element, conducting paper and specimen beach marking methods.

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Résumé On décrit le calibrage d'une technique PD (Potential Drop) en courant continu pour déterminer la longueur d'une fissure dans des éprouvettes de traction compactes comportant un entaillage sur un coin ou une nervure fissurée. On trouve un bon agrément entre les méthodes par élément fini, par papier conducteur, et par repérage des plages de propagation de fissure après rupture.

     

X-ray microtomography using a laboratory source: Measurement technique and comparison of reconstruction algorithms

A method of measuring the projections recorded by a laboratory-scale x-ray tomograph device is described. Numerical realizations of several methods that employ the apparatus of morphological image analysis are used to reconstruct images of a test object. It is shown that the estimators of the mean values of the coefficients of linear attenuation of media that are obtained are in good agreement with the requirements imposed on modern industrial, medical, and laboratory tomograph devices. __________ Translated from Izmeritel’naya Tekhnika, No. 2, pp. 19–24, February, 2008.     

Estimation and comparative study of JIC using different methods for 20MnMoNi55 steel

Fracture toughness is one of the key input variables to compute critical load of the structural components. The resistance against ductile fracture can be quantified either by the initiation value or by the entire resistance curve. Different standard methods like J_SZW, JSME and ASTM: E1820 etc. are mainly used to estimate the critical crack initiation value from the resistance curve developed by the J-integral test. However, the results vary from method to method and are even inconsistent for the same method. Pehrson and Landes suggested a simple method for estimation of the critical fracture toughness by identifying the critical point corresponding to the maximum load on load–displacement curve. In the present study, different standard methods along with the one suggested by Pehrson and Landes are used to find out the critical fracture toughness using 1T–CT and ½T–CT specimens of the material 20MnMoNi55 steel for varying temperatures and crack size. The results are analyzed to compare the merits of the different methods of estimation of fracture toughness.     

Precise comparison of experimental and theoretical SNRs in CO2 laser heterodyne systems

A detailed comparison of experimental and theoretical SNR in an IR laser heterodyne system has been made with three different signal analyzers. Good agreement, considerably better than a factor of 1.5, is reported. Accurate allowance was made for transmission in the receiver optics, the effective quantum efficiency of the detector due to shot noise domination by the local oscillator, and for coherent speckle effects across the collection aperture. The evaluation of SNR with a surface acoustic wave spectrum analyzer and digital integrator is described in some detail. As an illustration an absolute measurement of backscattering strength in the atmosphere from an airborne equipment at altitudes up to 13.1 km is provided.     

Development of a new ionisation chamber, for HP(10) measurement, using Monte-Carlo simulation and experimental methods

An ionisation chamber that directly measures the quantity personal dose equivalent, H(p)(10), is used as a secondary standard in some metrology laboratories. An ionisation chamber of this type was first developed by Ankerhold. Using the Monte-Carlo simulation, the dose in the sensitive volume as a function of the IC dimensions and the effects of the several components of the ionising chamber have been investigated. Based on these results, a new ionising chamber, lighter than the previous ones, is constructed and experimentally tested.     

Optimized coupling of a Gaussian beam into an optical waveguide with a grating coupler: comparison of experimental and theoretical results

The coupling efficiency of grating couplers is derived for a Gaussian incident beam. Its optimum value depends on the beam waist and on the position of a light spot with respect to the coupler edge for given grating parameters. The characteristic coupling length has been experimentally determined for the grating coupler studied. Relative measurements of the coupling efficiency as a function of incident beam characteristics are in good agreement with the numerical results.     

Brazing of titanium to steel with different filler metals: analysis and comparison

Evaluations of vacuum brazed commercially pure titanium and low-carbon steel joints using one copper-based alloy (Cu–12Mn–2Ni) and two silver-based braze alloys (Ag–34Cu–2Ti, Ag–27.25Cu–12.5In–1.25Ti) have been studied. Both the interfacial microstructures and mechanical properties of brazed joints were investigated to evaluate the joint quality. The optical and scanning electron microscopic results showed that all the filler metals interact metallurgically with steel and titanium, forming different kinds of intermetallic compounds (IMC) such as CuTi, Cu2Ti, Cu4Ti3, and FeTi. The presence of IMC (interfacial reaction layers) at the interfacial regions strongly affects the shear strength of the joints. Furthermore, it was found that the shear strength of brazed joints and the fracture path strongly depend on the thickness of the IMC. The maximum shear strength of the joints was 113 MPa for the specimen brazed at 750 °C using an Ag–27.25Cu–12.5In–1.25Ti filler alloy.     

Morphology,structure, and chemistry of nanoclusters in a mechanically alloyed nanostructured ferritic steel

Nanostructured ferritic steels have excellent elevated temperature strengths, creep resistances, and radiation tolerances due to the presence of a high density of Ti–Y–O-enriched nanoclusters. The compositions, morphologies, and structures of the smallest of these nanoclusters with maximum dimensions of ~2–4 nm were investigated in alloy 14YWT by high-resolution scanning transmission electron microscopy and atom probe tomography. Nanoclusters are found to be coherent with truncated rhombic dodecahedron morphologies defined by the {100} and {110} planes in the Fe matrix. Particles have compositions rich in Ti, O, Y, and Cr that are inconsistent with known oxide structures. The smallest nanoclusters appear to lack an identifiable crystal structure. Both nano-diffraction and focal series imaging through the sample thickness suggest that they are amorphous.     

Thermal properties of hierarchical YSZ and LZO ceramic microspheres with multi-scaled voids investigated by using theoretical,experimental and simulation methods

Heat transfer within ceramic feedstock powders is still unclear, which impedes optimization of the thermal and mechanical properties of the thermal sprayed coatings. The microspheres (yttria-stabilized zirconia YSZ and lanthanum zirconate LZO) were prepared via the electro-spraying assisted phase inversion method (ESP). The thermal properties of the two ESP microspheres and a commercial hollow spherical powder (HOSP) were investigated by using theoretical, experimental, and simulation methods. Thermal conductivity of the single microsphere was estimated via a novel nest model that was derived from the Maxwell-Eucken 1 and the EMT model. Thermal conductivity of a single YSZ/LZO-ESP microsphere prepared at 1100–1200 °C was within 0.36–0.75 W/m K, which was ～ 20 % lower than that of a single YSZ-HOSP microsphere with a similar porosity. Heat flux simulation showed that high tortuosity around the multi-scaled voids of the ESP microsphere led to a more efficient decrease in thermal conductivity compared with total porosity.