Study on the liquid metal flow field in FC-mold of slab continuous casting

The flow pattern and the velocity distribution of a liquid metal in the flow control mold(FC-mold) were investigated with a mercury model by analogy to the molten steel during continuous casting.The velocity measurement was conducted by the ultrasonic Doppler velocimeter(UDV)under various magnetic distributions and flux densities.The impingement intensity and the scouring intensity of the liquid metal to the narrow wall of the mold were calculated based on the measured data,and the influence of the magnetic flux density on the liquid metal flow in the mold was analyzed.The results showed that the surface of the liquid metal became more active when only the lower magnet was assembled,and the surface fluctuation was suppressed when further applying the upper magnetic field.It was indicated that when the upper and lower magnetic flux densities were 0.18 T and 0.5 T,respectively,the optimum conditions could be obtained,under which the free surface fluctuation could be suppressed,and a flow recirculation could rapidly form.     

Coupled field analysis of a piezoelectric bimorph disc in a direct write process

This paper investigates the behavior of a piezoelectric (PZT) bimorph disc within a Direct Write Process. A modified Continuous Inkjet Print (CIJ) method is utilized to selectively deposit a variety of conductive nano particulate materials for building functionally gradient materials (FGM). The spatial and temporal complexity of the novel CIJ based microfabrication process necessitates a computational solution to complement its experimental development. Static and modal coupled field finite element analyses were conducted for determining the operating frequency range of the PZT disc within a CIJ print head. The transient behavior of the PZT disc was subsequently analyzed in a conductive ink environment using a fluid–structure interaction (FSI) algorithm. Finally, parametric studies were conducted to generate empirical expression and to determine the relative importance that the density and kinematic viscosity of fluids had on the excitation behavior of the piezoelectric disc.     

Study on the microstructure and mechanical properties of explosive welded 2205/X65 bimetallic sheet

In this study, microstructural inhomogeneity and mechanical properties of explosive welded 2205 stainless steel/X65 pipe steel bimetallic sheets were investigated. The explosion-bonded 2205/X65 bimetallic sheets had good shear strength. The tensile shear fracture primarily occurred in the interior of X65 material and primarily exhibited dimple morphology. Fine crystal grains in the 0.5–2 μm range were found all over the narrow localized melted zone near the 2205/X65 interface, whereas a coarse columnar crystal structure growing along the perpendicular direction to the interface formed in the wider localized melted zone. Quasi-cleavage fracture morphology was observed in the coarse columnar crystal region after the stratified tensile test. The junction of the three regions near the interface with large differences in morphology was the weak point in the bimetallic sheet, where Y-shaped cracking easily occurred under a loading force. Stratified tensile test and micro-hardness tests for the explosively welded bimetallic sheet showed that severe hardening occurred in the 2205 cladding, and the most severe metal hardening occurred near the interface. Tests for 45° face bending and root bending tests were conducted under extreme conditions. The results showed that voids were prone to appeared in the peninsula and island morphologies near the interface.     

Acoustic softening in metals during ultrasonic assisted deformation via CP-FEM

In this paper, a phenomenological crystal plasticity model is modified to account for acoustic (ultrasonic) softening effects based on the level of ultrasonic intensity supplied to single and polycrystalline metals. The material parameters are identified using the inverse modeling approach by interfacing the crystal plasticity model with an optimization tool. The proposed model is validated and verified by comparing the microstructure evolution with experimental EBSD results reported in the literature. The model is able to capture the ultrasonic softening effect and the results show that as the ultrasonic intensity increases, the plastic deformation also increases. Differences in the stress-strain response are explained based on the slip system orientation tensor (Schmidt factors) which depends upon the crystal orientation.     

高海拔条件下浇注环氧树脂的工艺研究

环氧树脂浇注干式变压器由于其免维护、高可靠性、无污染、难燃防火及寿命终结后可回收利用等特征而受到重视和推广,在工矿企业、电站、机场、地铁、海洋钻井平台等领域获得广泛应用.由于生产厂坐落的位置海拔高度的不同存在当地的自然真空,对我们生产会造成一些影响,本文从此点出发,阐述在高海拔地区如何更好有效利用浇注设备浇注出合格的环氧树脂干式变压器的工艺.     

离心铸造液态金属充型流动过程中气泡的形核规律

对离心力场作用下液态金属充型流动过程中气体的溶解度、气泡的形核条件、形核功、临界形核半径以及形核率进行了定量研究.结果表明,在离心力场作用下气体的溶解度是一个梯度量,随着离心半径和离心角速度的增大而增大;气泡的形核功和临界形核半径也随着离心半径和离心角速度的增大而增大,而气泡的形核率相应地减小;离心半径和离心角速度越大,对气体溶解度和气泡形核的影响越明显;因此,在离心力场作用下可通过提高离心旋转角速度和离心半径减少气孔缺陷.     

Study of the compatibility between criteria in a set of materials requirements: Application to a machine tool frame

This contribution to materials selection theory aims at developing methodological methods and tools to analyse a complex set of material requirements with the objective of forecast whether there are materials that can fulfil it, or alternatively, if multi-materials selection is more likely to provide a solution. This “pre-analysis” of requirements examines the two main reasons which may prevent a single material solution: nonuniformity of materials space filling, or intrinsic contradiction between properties.A variety of statistical tools is used, based on Multivariate Analysis Methods as Principal Component Analysis (PCA) and the estimation of density distribution in the materials space. These tools allow to evaluate the “statistical compatibility” between the requirements and the available materials, and provides an estimate of the likelihood to find a single material solution or not. The methodology is applied to the research of a material for a machine tool frame.     

一种大型真空精密铸造炉结构布局的研究

本文首先分析了真空精密铸造炉在国内外的主流形式,并分析这些形式面对大型精密铸造时的不足.然后针对这些不足提出一种用于大型真空精密铸造炉结构布局及其衍生炉型.最后探讨了这种新的结构布局的发展机遇与前景.     

Application of a Solidification Mathematical Model and a Genetic Algorithm in the Optimization of Strand Thermal Profile Along the Continuous Casting of Steel

This work presents an optimization method based on a genetic algorithm applied to continuous casting process. A simple genetic algorithm was developed, which works linked to a mathematical model permitting the determination of optimum values for the water flow rates in the secondary cooling zones. First, experimental data (industrial) were compared with simulated results obtained by the solidification mathematical model, to determine the metal/cooling heat transfer coefficients along the machine by the inverse heat conduction problem method. The industrial data concerning surface strand temperature were obtained by using infrared pyrometers along a continuous caster machine during casting of both SAE 1007 and 1025 steels. In a second step, these results were used by a numerical code based on a genetic algorithm for determining optimum settings of water flow rates in the different sprays zones, which are conducive to the best quality of the solidified strand. The simulations were carried out by analyzing the solidification process during continuous casting to attain metallurgical restrictions concerning the reheating of strand surface temperature and metallurgical length.     

Study of the strain anisotropy of metals during nonmonotonic plastic deformation in a linear stress state

This article examines an experimental verification of the theory of anisotropic strain-hardening proposed by G. Backhaus. The tests were conducted under linearstress-state conditions in cyles of tension alternating with compression. The tests were conducted on cylindrical specimens of steels 45 and 30KhGSA by a method which makes it possible to realize such cycles on one specimen. It was established that the parameters which determine the Bauschinger effect and the hereditary effect of the strain history in the above-noted theory are the material characteristics determined from tension-compression tests. Functions which approximate these parameters are presented. In accordance with the theory, a new material characteristic is proposed: . This characteristic is the strain interval within which the stress state should be determined with allowance for strain anisotropy when there is a change in the loading trajectory. For strains in excess of the interval , the stress state should be determined from the theory of isotropic strain-hardening. The experimental data that is obtained shows that the Backhaus theory can be used to reliably evaluate the stress-strain state in tension-compression.Translated from Problemy Prochnosti, No. 12, pp. 53–56, December, 1990.     

Prediction of spatial distribution of the composition of inclusions on the entire cross section of a linepipe steel continuous casting slab

In the current study, the transformation in the composition of non-metallic inclusions from the molten steel to the solidified steel was studied and the composition distribution of inclusions on the cross section of a linepine continuous casting slab was predicted. During cooling and solidification of the continuous casting strand, Al₂O₃-CaO inclusions reacted with the bulk steel and transformed to CaS-Al₂O₃-MgO-(CaO) ones in the continuous casting slab. The composition of inclusions on the cross section of the slab varied with locations due to the varied cooling rate. A model was established to predict the distribution of the composition of inclusions on the cross section of the continuous casting slab, coupling solidification and heat transfer of the continuous casting slab, the kinetic mass transfer of the dissolved elements in the solid steel, and thermodynamic calculation of inclusion transformation at different temperatures. The composition transformation of inclusions mainly occurred at the temperature between the liquidus and solidus of the linepipe steel. Inclusions were mainly CaS-Al₂O₃-MgO-(CaO) in slab center and were MgO-Al₂O₃-CaO-CaS within the subsurface of the slab. In the slab, the transformation fraction of inclusions was less than 10 % at corners while it reached 70 % at 50 mm below the surface of the slab.     

Study on the rate of decomposition of amoxicillin in solid state using high-performance liquid chromatography

Abstract

Amoxicillin sodium salt degradation in solid state relies on a sequential reaction consisting of two pseudo-first-order processes. Amoxicillin trihydrate, now used in pharmaceutical formulations, is significantly more stable than sodium amoxicillin. It degrades according to Prout-Tompkins model. We studied the stability of amoxicillin at temperatures of 37°, 50°, 80°, 90°, 100° y 110° C. HPLC was chosen as the analytical method. Amoxicillin and its decomposition products are separated by reversed-phase (C18) HPLC with gradient elution.     

An investigation of the kinetics of the dissolution of metals in liquid metals by a rotating-disc method (Coefficient of diffusion of iron in liquid aluminum)

It was shown that the Levich equation can be used in the determination of the coefficients of diffusion of impurities in liquid metals when the dissolution is complicated due to the growth of protective intermetallic layers. The cause of wide (10–20-fold) discrepancies in previously published data on the coefficient of diffusion of iron in liquid aluminum was elucidated. It was shown that the dissolution of iron in liquid aluminum takes place by a mixed mechanism.     

Study of the nonlinear optical properties and behavior in phenoxy-phthalocyanines liquid at nanosecond laser pulses

The nonlinear optical properties of 2,9,16,23-phenoxy-phthalocyanine (Pc1) and 2,9,16,23-phenoxy-phthalocyanine-zinc (Pc2) in solution were investigated under excitation with nanosecond laser pulses at 532 nm. Based on five-level model, the nonlinear absorption in nanosecond regime was theoretically analyzed. The A-OS and OL behavior of Pc1 and Pc2 were further investigated with the pump–probe technique and transmission measurement technique. The results show that the A-OS response time is determined by the lifetime of the first triplet excited state of molecule, and Pc1 and Pc2 exhibit strong optical limiting effect at nanosecond laser pulses. These studies make the samples a promising possibility for device realization.     

Three-reference-curve method in constructing the equation of state of a gas and a liquid

A method of constructing the thermal equation of state of a gas and a liquid is considered; the method requires information only on three reference curves.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 48, No. 6, pp. 978–985, June, 1985.     

Effect of ultrasonic vibration on the grain refinement and SiC particle distribution in Zn-based composite filler metal

Refining the matrix microstructure of the composite is an effective method to avoid severe reinforcement particle pushing by the advancing solid–liquid interface during solidification. The effect of the ultrasonic vibration, which was injected into the melt at various stages of solidification, on the grain refinement and particle distribution in a Zn-based solidified composite filler metal was investigated. Perfect grain refinement was obtained with the application of continuous ultrasonic vibration. However, severe particle pushing by the sound radiation pressure was observed, resulting in serious particle segregation. Uniform distribution of SiC particles as well as grain refinement was obtained when proper intermittent ultrasonic treatment was applied.     

Effect of liquid lead-antimony alloys on the formation of cracks in steel in a state of strain

The selective embrittling effect of lead-antimony melts on steel 40 KhS (quenched to produce supercooled austenite) was studied, and data was obtained on the effect of the crystal structure of this steel on its behavior in contact with liquid metals.     

超声波对凝固石蜡中微粒分布的影响研究

研究了超声波的凝聚作用和空化作用,对石蜡中的微粒进行了超声处理实验,观察和分析超声处理后的石蜡中微粒的分布状况。实验主要探讨了石蜡中微粒的凝聚与超声处理时间和超声波功率之间的关系,观察对比不同功率和不同超声处理时间下石蜡中微粒的凝聚趋势,并对石蜡样本进行数码照相和金相显微分析,测出颗粒团块大小,以实验数据得出超声处理石蜡微粒凝团效果最好时所对应的超声波功率大小。