Advanced Materials Research Vols. 194-196

Abstract: The inhibition effect of tinidozole on the corrosion of mild steel in 3% HCl solution has been investigated through weight loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and quantum chemical calculations methods. The results show that tinidazole is an effective inhibitor for mild steel corrosion in HCl solution, and that the inhibition efficiency reaches a maximum value of 62% at the concentration of 400mg/L. Polarization measurement suggests that the tinidozole acts as mixed-type inhibitor. The Langmuir adsorption isotherm is proposed to interpret the interaction for the inhibitor molecule on metal surface. Furthermore, the quantum chemical calculation reveals that the adsorption of tinidozole is mainly concentrated around the imidazole ring.

Abstract: To lower the fracture appearance transition temperature (FATT) of Nb-treated HSLA H-beams further, boron-nickel-added Nb-treated HSLA H-beams were tempered after they were quenched at 870, 910 and 950°C respectively. Microstructures and mechanical properties, especially low temperature toughness of the experimental steels were investigated by scanning electron microscopy (SEM), uniaxial tensile test and Charpy impact test (V-notch). The results indicate that the FATTs of quenched & tempered specimens are all below -70С and that of some specimens is even below -90°С . Tensile strength of all quenched & tempered steels and their total elongation value are above 570 MPa and 21 % respectively. It can be seen that dual-phase microstructure of ferrite and tempered martensite in steels leads to the best low temperature toughness, and carbides along grain boundaries are beneficial to low temperature toughness.

Abstract: The characteristic temperatures of the selected quaternary CaO-MgO-Al₂O₃-SiO₂ slags have been measured by the hemisphere method. The effects of the basicity value and Al₂O₃ content studied. The results indicated that basicity and the Al₂O₃ content had obvious influence on the characteristic temperatures of the selected slags. All of the softening temperature, the hemisphere temperature and the flow temperature decrease with the increasing of the basicity value. Under the same content of CaO, the characteristic temperature decreased sharply by adding Al₂O₃. The solidus and liquidus temperatures computed from the FactSage database were compared with the present experimental observations as well as the melting temperature information of the DSC measurements. The results also indicated that it is possible to get a reasonable idea of the solidus temperature from the hemisphere temperature while the flow temperature would indicate the liquidus temperature.

Abstract: The effects of temperature and strain rate on the thermal deformation-behavior of Cu-P weathering steel were studied by using thermal simulator. And the true stress-true strain curves at different thermal deformation conditions were got. Then the features of the microstructure of the steel under different temperatures and strain rates were analyzed. The results show that with the same deformation dimensions and strain rates, when the deformation temperatures were higher, the recrystallization would proceed much easier, and the size of the recrystal grains could be also larger. And with the same deformation dimensions and temperatures, when the strain rates were lower, the recrystallization could also occur easier, and the proportion and size of the recrystal grains were larger.

Abstract: Physical modeling of argon shroud was carried out using a 2D 1:1 scaled model in order to gain the protection effect in steel casting. The speed field of protective gas around the steel steam was measured by PIV technique. The oxygen distribution was measured by an oxygen sensor. The main findings are following: (1)The distance between the ladle and the collar should be minimized to reduce the oxygen entrainment.(2)For single inlet, the oxygen contents were lower in the case of horizontal gas inlet than vertical gas inlet.(3)A dual gas inlet configuration would be more effective than a single inlet in ordinary operation conditions.

Abstract: A typical kind of silicate gangue — sodium pyroxenite (mainly containing NaFeSi₂O₆) in Baiyunebo iron ore is selected as the research object in this paper. The endothermic peak and the change of quality is definited by means of thermal analysis (DSC and TG) in the rising process. And then the samples are sintered at the peak temperatures. The main ingredients of sodium pyroxenite and the resultants are definited by means of X-ray diffraction analysis (XRD). The experiment ascertains the change law of physical and chemical properties of sodium pyroxenite such as thermal decomposition, softening, melting temperatures and the corresponding resultants, which provides basic data for exploring the formation mechanism of complex calcium ferrite (SFCA) in baogang special sintered ore.

Abstract: Effects of different impact angles such as 45°and 90°on the erosion-abrasion properties of hypereutectic Al-Mn alloy and its composites reinforced with Al₂O₃ particulates were studied by rotating erosion-abrasion test, and the microstructure and the worn surfaces were analyzed. The results show that the as-cast Al-Mn alloy is composed of aluminium-manganese solid solution, MnAl₆ and Al₁₁Mn₄ phase, while the δ-Al₂O₃ particles are included in the composites besides the aforementioned microstructures. With elongating the erosion time, the wear rates of the Al-Mn alloy and its composites increase at the impact angle of 90°, whereas they firstly increase and then decrease , and there is a maximum at 45°. The distortion wear caused by the normal stress is dominant at 90°, which lead to the erosion pits on the worn surface. However, the cutting wear by the shear stress is predominant at 45°, which result in the ploughs.

Abstract: The composition and heat treatment of heavy section forging steel for reactor pressure vessel were optimized applying physical and numerical simulation methods, including numerical simulation to calculate temperature distribution during quench of model forging, artificial neural network to predict CCT diagrams of steels and small sample control cooling to simulate specific heat treatment. And the influence of compositon and heat treatment on microstructure and properties were discussed. Results showed that the experimental steel obtained satisfactory properties based on optimization of chemical composition and heat treatment. It is estimated that the hardenability and temper stability of experimental steel were improved by tungsten alloyment and higher temperature temper was good for superior microstructure, proper strength and better toughness. In the present work, application of simulation methods is proved to be reasonable for study on heavy section forging steel.

Abstract: The effects of compound silicate gangue on mineral composition and microstructure of sinter produced by Baiyunebo iron ore concentrates was studied by using mini-sintering test device and optical microscope. The result showed that compound silicate gangue has lower melting point, wider melting temperature range, longer melting time and melts easily to form glassiness during the sintering process. It can promote the solution of CaO and CaF₂ in glassy phase, which affects viscosity and fluidity of glassy phase as well as the homogeneity of sinter microstructure. The compound silicate gangue intensely inhibits the generation of complex calcium ferrite and cuspidine as well. The major mineral compositions of sinter are hematite and glassy phase. The sinter exhibits multi-cavities and grainy structure when SiO₂ exists entirely in the form of compound silicate gangue.

Abstract: Based on practical production technology, using some methods like segregation index analysis, the research is focused on the relationship between the maximum segregation index of carbon, phosphorus, sulfur in superwide slab and rolling reduction, reduction ratio, reduction rate of superwide slab caster. During the process of soft reduction, the theory that the minimum of the maximum segregation index corresponds to the technological parameters like optimal rolling reduction, optimal reduction ratio, optimal reduction rate of the superwide slab caster can be provided as a theoretical basis for the production of superwide slab.