Micro-segregation model calculation of residual tin in boiler and pressure vessel steel

Tin is a typical residual element in steel and mainly originates from Sn-containing complex iron ore and steel scrap. The segregation of Sn in steel is harmful to the performances of steel. In this paper, the micro-segregation of residual element Sn during the solidification process of boiler and pressure vessel steel by micro-segregation model was studied. The results showed that the micro-segregation degree of Sn reduces apparently with the increase of cooling rate and remarkably deteriorates during the solidification process. When the initial content of C is higher than 0.1%, it will cause the solidification transform of the solid phase converting from the ferrite phase to austenite phase and the significant increase in the micro-segregation degree of Sn. However, increasing the initial contents of Si, Mn, P and S separately has non-significant effects on the micro-segregation degree of Sn. In addition, the improvement of initial content of Sn will lead to the micro-segregation degree decrease of Sn and has an inapparent impact on zero strength temperature and zero ductility temperature of the boiler and pressure vessel steel.     

板结构计算模型的新发展

现代复合材料层合板具有高强和轻型的突出优点，从而在军工和民用等诸多领域发挥着重要作用。这种板结构的特点是随着纤维走向的不同，层间材料的物理-力学特性发生剧烈变化。沿板厚方向变形的梯度比较陡峭，并在层间结合面处发生强不连续，呈现zig-zag （锯齿状）现象。这导致横向剪应变在板的静态和动态响应中发生重要作用，不计横向变形的经典组合板计算模型CLPT难以适应现代多层板计算分析的需要。考虑横向剪切变形影响的板的计算模型得到重视和发展。需要指出，现有各种考虑剪切变形影响的计算模型虽然有了很大的发展，但在全面和准确性上仍然存在一定的不足，难以适应现代多层组合板横向力和物理性能多变的情况。模型预测的沿板厚方向位移和应力的变化规律难以通过严格的检验。本文提出的以比例边界有限元为基础的正交各向异性板的数值计算模型，同时可适用于各种薄板与厚板的分析，对现代复合材料层合板的分析具有特殊的优越性。所得到的板的位移、正应力和剪应力沿板厚方向的变化，与三维弹性理论的标准解高度吻合。数值算例进一步表明，随着层间纤维走向的变化，板内位移场和应力场沿板厚方向剧烈变化所呈现的锯齿现象均可以精准地进行模拟。据此，本文建议方法对现代板分析的广泛适应性和高度准确性得到了充分论证。     

Polymer complexes. LXXVI. Synthesis,characterization, CT‐DNA binding,molecular docking and thermal studies of sulfoxine polymer complexes

Novel polymer complexes of 8‐hydroxyquinoline‐5‐sulfonic acid hydrate ( H ₂ L ) with Cu²⁺, Co²⁺ and Ni²⁺ chloride were prepared and characterized. Microanalysis, magnetic susceptibility, IR spectra, electron spin resonance, mass spectra, X‐ray, molar conductance, thermal, and UV–Vis spectra studies have been used to confirm the structure of the prepared polymer complexes. The molecular and electronic structures of the hydrogen bond conformers for ligand ( H ₂ L ) were optimized theoretically and the quantum chemical parameters were calculated. On the basis of elemental and IR data, the chemical structure of metal chelates commensurate that the tri‐dentate (H₂L) coordinate to metal chlorides through oxygen atom of phenolic OH and oxygen atom of SO₃‐H group by replacing H atoms and nitrogen of the quinoline ring. The magnetic studies suggested the octahedral geometrical structure for all produced polymer complexes with general formula {[ML (OH₂)₃] .xH₂O}_n (M = Cu²⁺, x = 1.; Co²⁺, x = 2 and Ni²⁺, x = 2) in molar ratio (1:1). Coats–Redfern and Horowitz–Metzger methods have been used for calculating the activation thermodynamic parameters of the thermal decomposition for H ₂ L and its polymer complexes. The interaction between H ₂ L and its transition metal complexes with the calf thymus DNA (CT‐DNA) was determined by UV–Vis spectra. Binding efficiency between H ₂ L with the receptors of the prostate cancer (PDB code 2Q7L Hormone) and the breast cancer (PDB code 1JNX Gene regulation) was studied by molecular docking. The inhibition behaviour of H ₂ L against the corrosion of carbon steel / HCl (2 M) solution was studied by weight loss, Tafel polarisation, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The adsorption isotherm was found to be Friendlish isotherm. The morphology of inhibited carbon steel? s surface was studied using scanning electron microscope (SEM) and energy dispersive X‐ray spectroscopy (EDS).     

RAFM钢TIG焊和电子束焊疲劳性能实验和分析模拟

利用ANSYS 对低活化铁素体马氏体(RAFM)钢进行非熔化极气体保护焊(TIG 焊)与电子束焊的抗疲劳模拟分析，再利用SDS200 电液伺服疲劳试验机对TIG 焊和电子束焊的两种RAFM 钢试件进行实验。通过施加相同梯度负荷对TIG 焊和电子束焊试件进行焊缝的疲劳性能实验。与实验结果对比分析，结果显示电子束焊优于 TIG 焊，但在一定负载下可以用TIG 焊代替电子束焊。     

Electrochemical Characterization of Stainless Steel as a New Electrode Material in a Medical Device for the Diagnosis of Sudomotor Dysfunction

An electrochemical sensor detects the risk of diabetes and prediabetes; low potentials are applied to nickel electrodes and electrical responses are measured. Although the contact of nickel with skin is short, the risk of allergical reactions cannot be discarded. SS 304L, with lower Ni content, was tested in carbonate buffer solutions containing chloride, lactate and urea to investigate its sensitivity to different parameters in sweat and compare it to nickel. The results show that SS 304L is a suitable material for the assessment of sudomotor dysfunction due to its high capacity to detect the deviation in Cl^? concentration. Sensitivity of SS 304L to Cl^? is much higher than for nickel.     

Microstructure change in deuterium implanted CLAM steel induced by electron irradiation

As Reduced Activation Ferritic/Martensitic (RAFM) steel is considered the primary candidate for use as a structural material in fusion power reactors,many countries are developing different kinds of RAFM.China is developing new CLAM (China Low Activation Martensitic) steel.The study investigates microstructural changes in CLAM steel implanted with deuterium ions induced by 1250 keV electron irradiation from R.T.to 873 K,and observes both the growth and shrinkage of the defect clusters produced by deuterium ...     

Dislocation-density-based constitutive modelling of tensile flow and work-hardening behaviour of P92 steel

The flow and work-hardening behaviour of tempered martensitic P92 steel have been investigated using phenomenological constitutive model in the temperature range 300–873 K for the strain rates ranging from 3.16 × 10^?5 to 1.26 × 10^?3 s^?1. The analysis indicated that the hybrid model reduced to Estrin–Mecking (E–M) one-internal-variable model at intermediate and high temperatures. Further, the analysis also indicated that dislocation dense martensite lath/cell boundaries and precipitates together act as effective barriers to dislocation glide in P92 steel. The flow behaviour of the steel was adequately described by the E–M approach for the range of temperatures and strain rates examined. Three distinct temperature regimes have been obtained for the variations in work-hardening parameters with respect to temperature and strain rate. Signatures of dynamic strain ageing in terms of the anomalous variations in work-hardening parameters at intermediate temperatures and the dominance of dynamic recovery at high temperatures have been observed. The evaluation of activation energy suggested that deformation is controlled by the dominance of cross-slip of dislocations at room and intermediate temperatures, and climb of dislocations at high temperatures.     

The polynomial reconstruction problem: The first 50 years

The problem of reconstructing the characteristic polynomial of a graph of order at least 3 from the collection of characteristic polynomials of its vertex-deleted subgraphs was posed by Cvetkovi? in 1973 as a spectral counter part to the well-known Ulam's reconstruction conjecture. Over the last 50 years, this problem has received notable attention, many positive results have been obtained, but in the general case the problem is still unresolved. In particular, no counter example is found in literature. In this expository paper we survey classical and some more recent results concerning the polynomial reconstruction problem, discuss some related problems, variations and generalizations.     

Application of electromagnetic processing for development of high-performance sintered powder metal parts

Electromagnetic processing was used to study the effects of electro-magneto forming on the dimensional control and thermal stability of sintered powder metal (PM) parts. The investigation was carried out on sinter-hardened, low chromium-molybdenum bainitic steel. The results show an increase in the microhardness of about 14% for the electromagnetic processed parts compared to the as-sintered parts. This was attributed to the 2% increase in the density, 17% and 29% reduction in the volume fraction of porosity and width of the bainitic lath, respectively, due to the electromagnetic processing. Dimensional characterization was carried out using a vertically aligned push-rod dilatometer. After four thermal cycles of heating and cooling, at a controlled rate of 5 °C/min to 1000 °C, the electromagnetic processed parts exhibited reduced dimensional change of about 44% lower than for the as-sintered parts. This is significantly important for applications that demand high dimensional tolerance and performance, especially at elevated temperatures.     

Dislocation density crystalline plasticity modeling of lath martensitic microstructures in steel alloys

A three-dimensional multiple-slip dislocation density-based crystalline formulation, specialized finite-element formulations and Voronoi tessellations adapted to martensitic orientations were used to investigate large strain inelastic deformation modes and dislocation density evolution in martensitic microstructures. The formulation is based on accounting for variant morphologies and orientations, retained austenite and initial dislocation densities that are uniquely inherent to martensitic microstructures. The effects of parent austenite orientation and retained austenite were also investigated for heterogeneous fcc/bcc crystalline structures. Furthermore, the formulation was used to investigate microstructures mapped directly from SEM/EBSD images of martensitic steel alloys. The analysis indicates that variant morphology and orientations have a direct effect on dislocation density accumulation and inelastic localization in martensitic microstructures, and that lath directions, orientations and arrangements are critical characteristics of high strength martensitic deformation and behavior.