Prediction of elastic strain recovery of a formed steel sheet considering stiffness degradation

The aim of this work is to show first, how the springback of a steel sheet drawn part is affected by the stiffness degradation, as it results from the damage evolved during forming process, and second, to build a respective modeling approach to take this degradation into account. For the consideration of the orthotropic elastic properties degradation we develop an approach, based on the Mori-Tanaka theory, where damage is considered by inclusion of ellipsoidal cavities. The respective void shape evolution is proposed to be identified with the measurements of elastic modulus in two perpendicular directions during the uniaxial tensile test of a flat specimen at different loading stages. The proposed approach is coupled with the Gurson-Tvergaard-Needleman (GTN) plastic potential, though it could be substituted by almost any other continuum damage model. At the end the presented approach is experimentally validated by a simple springback test, developed by authors. A very good agreement between by calculation predicted and measured springback amount is observed.     

Inhibition effect of butan-1-ol on the corrosion behavior of austenitic stainless steel (Type 304) in dilute sulfuric acid

The electrochemical behavior of austenitic stainless steel (Type 304) in 3 M sulfuric acid with 3.5% recrystallized sodium chloride at specific concentrations of butan-1-ol was investigated with the aid of potentiodynamic polarization, open circuit measurement and weight loss technique. Butan-1-ol effectively inhibited the steel corrosion with a maximum inhibition efficiency of 78.7% from weight-loss analysis and 80.9% from potentiodynamic polarization test at highest concentration studied. Adsorption of the compound obeyed the Freundlich isotherm. Thermodynamic calculations reveal physiochemical interactions and spontaneous adsorption mechanism. Surface characterizations showed the absence of corrosion products and topographic modifications of the steel. Statistical analysis depicts the overwhelming influence and statistical significance of inhibitor concentration on the inhibition performance.     

CeO_2负载多孔碱激发钢渣基催化剂的制备及其光催化性能

固体废弃物高附加值利用是资源可持续发展的重要途径之一,创新性的提出了以丙烯酸树脂乳液为孔形成剂,对碱激发钢渣基胶凝材料的孔结构进行调变,制备出新型多孔碱激发钢渣基胶凝材料,采用初湿浸渍法合成了一种新型的CeO_2负载的多孔钢渣基催化剂。利用XRF,XRD,BET,UV-Vis DRS等手段对光催化剂的组成、结构及光谱性能进行了表征,评价了其光催化分解水制氢活性。结果表明:孔形成剂的加入,改变了碱激发钢渣基胶凝材料的孑L结构,其介孔体积增加了70.27%,负载8 Wt%CeO_2的光催化剂介孔体积增加了144.14%。在模拟太阳光源辐照6 h后,负载8 Wt%CeO_2的光催化剂的最高产氢活性(7 653μmol·g~(-1))和产氢速率[1 275.5μmol·(g·h)~(-1)]归因于介孔体积增加了水分子的传质速率以及高分散的CeO_2活性组分与载体中FeO形成的耦合半导体促进了光生电子-空穴对的高效分离。     

Helium and point defect accumulation: (i) microstructure and mechanical behaviour

Ferritic/martensitic (F/M) steels are good candidate structural materials for the future fusion reactors and spallation sources. However, irradiation of steels is known to produce hardening, loss of ductility, shift in ductile to brittle transition temperature (DBTT) and reduction of fracture toughness and creep resistance starting at low doses. Helium (He), produced by transmutation during the irradiation, also impacts mechanical properties. Numerous experimental and theoretical studies on the evolution of the microstructure of steels under irradiation have been conducted until now. We review the effect of irradiation-induced point defects and in particular of He on the mechanical properties of F/M steels. To cite this article: R. Schäublin et al., C. R. Physique 9 (2008).     

Radiation attenuation and nuclear properties of high density concrete made with steel aggregates

Abstract

The fast neutron and gamma ray spectra measured behind different thickness of steel scrap concrete with density of 4 g/cm³ have been studied. The mix proportions by weight of this type of concrete were 1 cement: 6.89 steel scrap: 2.9 sand and 0.5 Water. Comparison with a standard ordinary concrete of density 2.3 g/cm³ have been carried out. The measurements were made using a collimated beam of both gamma rays and neutrons emitted from one of the horizontal channel of the Egyptian Research Reactor-1. A fast neutron and gamma ray spectrometer with a stilbene crystal was used to measure the spectra of fast neutrons and gamma rays. Pulse shape discrimination using the zero cross over technique was used to separate the photon pulses from the electron pulses. The equation due to Schmidt has been modified and applied for determining the neutron effective removal cross sections (～_R) for steel scrap, ordinary, hematite–serpentine, ilmenite–limonite and ilmenite concretes. This equation gives results which are in good agreement with the measured values. The derived empirical equation in a previous work to calculate the neutron integral flux behind different thicknesses of different types of concretes, gives good results for steel scrap concrete under investigation comparing with the corresponding experimental data. Total neutron macroscopic cross sections, linear attenuation coefficients for gamma rays and the half-value layers for both radiations at different energies have been obtained for steel scrap concrete and comparing with the corresponding values of ordinary concrete. The results show that steel scrap concrete is better than ordinary, hematite–serpentine, ilmenite–limonite and ilmenite concretes from the radiation shielding point of view.     

Effect of pulegone and pulegone oxide on the corrosion of steel in 1 <Emphasis Type="Italic">M</Emphasis> HCl

The inhibitive action of pulegone and pulegone oxide toward acid corrosion of steel in molar hydrochloric acid was studied by weight loss measurements, potentiodynamic polarization, and impedance spectroscopy (EIS) methods. The pulegone is extracted starting from oil of Pennyroyal Mint (Mentha pulegium). The natural compound was found to delay the corrosion rate. The pulegone oxide is prepared by oxidation of pulegone. The inhibition efficiency was found to increase with the inhibitor content to attain 81 and 75% at 5 g dm⁻³ for pulegone and pulegone oxide. The increase in temperature leads to an increase in the inhibition efficiency of the natural compared. Correspondence: Belkheir Hammouti, Laboratoire de chimie Appliquée & Environnement, Faculté des Sciences, B.P. 717, 60000 Oujda, Morocco.     

高碘酸钾法测钢铁及合金中锰的改进建议

试样经酸溶解后,以磷酸-高氯酸混合酸(4 1)或(9 1)氧化至冒烟.在硫酸、磷酸介质中,用高碘酸钾将锰氧化到七价,测其吸光度.     

Estimation of boron isotope ratios using high resolution continuum source atomic absorption spectrometry

In the production of ¹⁰B enriched steels, the production–recycling process needs to be closely monitored for inadvertent mix-up of materials with different B isotope levels. A quick and simple method for the estimation of boron isotope ratios in high alloyed steels using high resolution continuum source flame AAS (HR-CS-FAAS) was developed. On the 208.9 nm B line the wavelength of the peak absorption of ¹⁰B and ¹¹B differs by 2.5 pm. The wavelength of the peak absorption of boron was determined by fitting a Gauss function through spectra simultaneously recorded by HR-CS-FAAS. It was shown that a linear correlation between the wavelength of the peak absorption and the isotope ratio exists and that this correlation is independent of the total boron concentration. Internal spectroscopic standards were used to compensate for monochromator drift and monochromator resolution changes. Accuracy and precision of the analyzed samples were thereby increased by a factor of up to 1.3. Three steel reference materials and one boric acid CRM, each certified for the boron isotope ratio were used to validate the procedure.     

Three generations of inorganic phosphates in solvent and water-borne paints: A synergism case

This research work is intended to compare the anti-corrosive properties of three generations of inorganic phosphate pigments in solvent-based paints and in water-borne ones, both of the epoxy type. The anti-corrosive properties of phosphate pigments were assessed by means of electrochemical techniques (corrosion potential measurements, polarisation tests, etc.), employing a steel electrode dipped into pigments suspensions. The behaviour of these pigments in anti-corrosive paints, formulated with different binders, have been studied by accelerated (salt spray cabinet and humidity chamber) and electrochemical tests (corrosion potential and ionic resistance measurements).Accelerated and electrochemical tests allowed to differentiate the anti-corrosive performance of the three phosphates studied in this research. These test are also able to detect and characterise possible synergism between the water-borne resin and the pigments.     

Growth of carbon nanotubes from waste blast furnace gases at atmospheric pressure

Carbon emissions from industrial sources are of major global concern, especially contributions from the steel manufacturing process which accounts for the majority of emissions. Typical blast furnace gases consist of CO₂ (20‐25%), CO (20‐25%), H₂ (3‐5%) and N₂ (40‐50%) and trace amounts of other gases. It is demonstrated that gas mixtures with these compositions can be used at atmospheric pressure to grow carbon nanotubes (CNTs) by chemical vapor deposition (CVD) on to steel substrates, which act as catalysts for CNT growth. Computational modelling was used to investigate the CNT growth conditions inside the CVD chamber. The results show that industrial waste pollutant gases can be used to manufacture materials with significant commercial value, in this case CNTs.