A new process for manufacturing organically compounded bentonite was developed successfully based on the organic intercalation and layered structure of bentonite. The main steps in the proposed process included wet sodium activation of bentonite ore, organic compounding and high-pressure roll grinding. The optimum procedure is recommended as follows: 5 mass% of sodium carbonate powder and 30 wt.% water are added to activate the bentonite ore for 24 h to prepare activated bentonite; 0.5 wt.% of organic molecules are added into the activated bentonite for organic compounding for 12 h; then, the high-pressure roll grinding is followed to treat the organically compounded bentonite; and finally, drying and fine grinding are performed for preparing the final organically compounded bentonite product with 10 wt.% moisture and 98% passing 0.074 mm. The obtained organically compounded bentonite was characterized using an X-ray diffractometer, a scanning electron microscope and an X-ray photoelectron spectrometer. To confirm the effect of organically compounded bentonite on green balls, the pelletizing tests were carried out. The results showed that high-pressure roll grinding can not only enhance the ability of the crystal layer to hold the combined water, but also strengthen the intercalation compounding of the organic additive, which is beneficial for the formation of a fiber-interlaced structure of the organically compounded bentonite and improves the quality index of the bentonite itself. Also, the organically compounded bentonite is helpful to improve the indexes of green balls.

In order to increase the contact area and promote the mass transfer process of gas and liquid, the process of the bubble refinement in a metallurgical reactor with mechanical agitation was studied by physical simulation. Based on the capillary number, a prediction equation for the bubble refinement was established. The effects of the gas flow rate, the stirring speed and the stirring depth on the bubble refinement in the reactor were discussed in detail. The distribution of the bubble diameter in the
reactor was obtained under different conditions. The results show that when the stirring speed reaches 300 r/min, the bubble diameter mainly distributes in the range of 1–2 mm. A higher gas flow rate may increase the number of bubbles in the melt and promote the bubble refinement process. The mechanism of bubble refinement under mechanical agitation was analyzed, and the results indicated that the stirring speed, the blade area and the blade inclination are the main influencing factors.

The chromium-bearing titanomagnetite ore will turn to be the important raw material for blast furnace process in Panxi area, China. The reduction behavior of Cr₂O₃ between CaO–SiO₂–Al₂O₃–TiO₂–Cr₂O₃ and Fe–C systems was investigated. The effect of TiO₂ content in the slag system on the reduction of Cr₂O₃, TiO₂, and SiO₂ and the consumption of C in hot metal was investigated by both theoretical calculation and physical experiment. The theoretical calculation results reveal that higher reduction temperature promotes the reduction of Cr and Ti, while high basicity and TiO₂ content have little influence on the reduction of chromium but significantly influence the reduction of Ti. The smelting reduction experiment results show that the content of Cr in hot metal significantly increases with extending the reduction time and decreases with the increase in TiO₂ content. However, the content of Ti in hot metal significantly increases as the TiO₂ increases, reaching 0.073, 0.085, 0.107, and 0.121 wt.% for 5, 10, 15, and 20 wt.% of TiO₂ input, respectively. Kinetic studies proved that the reduction of Cr₂O₃ was a first-order reaction. The addition of TiO₂ inhibited the reduction of Cr₂O₃ and resulted in the decrease in reaction rate constant.

Carbon dissolution from four types of metallurgical cokes and graphite was investigated by using immersion rods in a resistance furnace to clarify the influence of factors governing the rate of carbon dissolution from carbonaceous materials into Fe–Mn melts at 1550 °C. The factors studied were the microstructure of carbonaceous materials, roughness, porosity and the wettability between carbonaceous materials and the melt. Carbon/metal interface was characterised by scanning electron microscopy accompanied with energy-dispersive X-ray spectrometry to investigate the formation of an ash layer. The results showed that coke E had the highest dissolution rate. Surface roughness and porosity of the carbonaceous materials seemed to be dominant factors affecting the dissolution rates. Further, crystallite size did not have a significant effect on the dissolution rates. Solid/liquid wettability seemed to affect the initial stage of dissolution reaction. The dissolution mechanism was found to be both mass transfer and interfacial reactions.

The research of carbon content along the casting direction of 82B cord steel billets is of great significance for improving the quality of cord products from subsequent processing. However, the traditional segregation and billets quality evaluation methods have certain limitations, such as sampling length and analysis area, which affect the accuracy of quality judgment. Thus, the statistics of extreme values (SEV) was introduced to predict the maximum value of carbon element content along the casting direction, which can quantitatively characterize the segregation degree. The size of the selected billet is 150 mm × 150 mm, and the sampling location is the centerline of the billet. The experiment was conducted by considering the effect of cooling intensity and casting speed on the maximum value of carbon element content. Firstly, the calculation results show that the SEV method can predict the maximum value of carbon element content along the casting direction of 82B cord steel, and the SEV method is proved to be effective by analyzing the carbon distribution and fluctuation in billets. To some extent, the SEV method can break the limitations of the sampling length and analysis area by predicting the maximum value of carbon element on a larger range of continuous casting billets with few samples. During the continuous casting process, the increase in cooling intensity makes the surface shrinking rate increase, which can slow down the flow of solute-enriched liquid to the center, and the center segregation can be reduced. On the other hand, the function area of the final electromagnetic stirring can be expanded with the increase in the casting speed, which can reduce the concentration of carbon element in the center of the billets and reduce the maximum value of carbon element content. It can provide a new theoretical reference for the quantitative calculation of carbon content in continuous casting billets and the quality evaluation of continuous casting billets.

To further improve the comprehensive properties of 42CrMo/Q235 laminated shafts produced by cross wedge rolling, the heat treatment of the shafts was studied. Tensile and bending tests were carried out to compare the changes in mechanical properties before and after heat treatment. The results showed that the interfacial bonding strength increased most after tempering at 350 °C for 45 min. The microstructure of the interface was observed using a digital microscope. The results showed that the dispersed oxides on the interface were basically eliminated by using the scheme of tempering at 350 °C and holding for 45 min. The reasons for the change in mechanical properties were explained from the point of the interfacial microstructure. Scanning electron microscopy was used to analyze the micro-morphology of the tensile fracture. It was observed that after tempering at 350 °C and holding for 45 min, the dimple holes became larger and deeper, and the structure of fracture became more uniform and stable. From the point of the tensile fracture morphology, the reasons for the change in mechanical properties were explained as well.

The oxidation behavior of a newly designed Co–Ni-based alloy with varied addition of Ti (1.4 and 2.1 wt.%, hereafter referred as 1.4Ti and 2.1Ti alloys) was explored in air at 900 °C. It is found that an outer oxide layer composed of CoO, an intermediate oxide layer composed of intermittent TiO₂ plus continuous Cr, W-rich oxides, and an inner oxidized region composed of Al₂O₃ were formed on the surface of 1.4Ti alloy, whereas the oxide structure of 2.1Ti alloy was composed of CoO as the outer oxide layer, continuous TiO₂, Cr₂O₃, and WO₃ as intermediate oxide layer, and Al₂O₃ as the inner oxidized region. With increasing Ti content, continuous TiO₂ films formed in the intermediate oxide layer, which would lead to the formation of compact Cr₂O₃ and improved oxidation resistance after 100 h oxidation at 900 °C. These observations indicated that Ti addition can improve the high-temperature oxidation resistance of Co–Ni-based alloys.

The so-called low-density steels have generated a lot of interests with their high specific strength and ductility due to the addition of the light element Al. In order to accelerate the low-density steel design, a thermodynamic database has been developed within the present author group. Two Al-containing systems, i.e., Cr–Al–C and Ni–Al–C, were modeled and optimized with CALPHAD approach based on the reliable binary descriptions. For Cr–Al–C system, the Gibbs energy of Cr₂AlC phase was described by a temperature-dependent polynomial with the aid of the experimental data on the heat capacity, instead of estimating heat capacity from Neumann–Kopp rule. The incongruent melting temperature of Cr₂AlC is 1762 K with the invariant reaction of liquid + Cr₃C₂ + Al₄C₃→Cr₂AlC. The phase equilibria between Cr₂AlC and binary phases were well reproduced by using the present model parameters. For Ni–Al–C system, the liquid, fcc and bcc phases have been optimized to fit the carbon solubility in these three phases. A good agreement between the calculated and experimental data has been obtained using the present description of Ni–Al–C system. The reliable descriptions of the two ternary systems developed in the present work can be implemented into the thermodynamic database for low-density steels.

The effect of dew points (-50, -10 and +10 °C) on the galvanizing properties of a high-manganese twinning-induced plasticity (TWIP) steel was studied. Scanning electron microscopy (SEM), glow discharge optical emission spectrometry (GDOES) and X-ray photoelectron spectroscopy (XPS) were used for microscopic observation and qualitative analysis of the interfacial layer between the steel surface and the zinc layer after hot-dip galvanizing. SEM analysis results show that three different morphologies of metallic oxides are formed on the interfacial layer under the different dew points. GDOES results show that Al is present in the molten zinc, reacting with Fe on the steel surface to form Fe₂Al₅, which can increase the galvanizing properties. XPS results show that the valence states of Mn in the interfacial alloy layer are Mn²⁺ and Mn⁴⁺, and the valence states of Fe are Fe⁰, Fe²⁺ and Fe³⁺. The experimental results show that the hot-dip galvanizing performance is the best at -10 °C and the formation of Mn and Fe intermetallic oxides has a bad effect on hot-dip galvanizing behavior of the high-manganese TWIP steel. The types of the formed surface oxides (MnO, Mn₃O₄, Mn₂O₃, FeO, and Fe₂MnO₄) on the surface of the steel sheet are confirmed. It can obtain the best hot-dip galvanizing performance of the high-manganese TWIP steel by controlling the dew point from -10 to -5 °C.

For QSTE700 high-strength steel rectangular welded tube, the mechanical properties of the weld zone vary with the distance from the centerline of the weld. Therefore, the accurate description of constitutive relationship of the weld zone is of great significance for the study of formability of QSTE700 rectangular welded tube. Firstly, the mechanical properties of parent and mixed specimens containing weld zone and parent zone were obtained by uniaxial tensile test. And based on the microhardness test, the width and the microhardness distribution of the weld zone were determined. Secondly, by subdividing the weld zone into several small areas, and combining with the rule of mixtures and nanoindentation test, the continuous functional relationships of strength coefficient K, hardening coeffecient n and elastic modulus E were obtained, and then, the continuous constitutive relationship of QSTE700 rectangular welded tube was established. Finally, the validity and reliability of the continuous constitutive relationship of welded tube were verified by nanoindentation test and rotary draw bending of rectangular welded tube. Besides, it was found that the finite element model of rotary draw bending of QSTE700 rectangular welded tube established by using the continuous constitutive relationship can well simulate the cross section deformation and wall thickness variation.

Composite coating on GH4169 alloy is prepared by laser cladding yttria-stabilized zirconia (YSZ)@Ni core–shell powders mixed with NiCoCrAlY alloy powders. The cyclic oxidation behavior of the coatings, especially the growth process of the oxide layer, is investigated based on experimental research and first-principle calculations. The results indicate that the oxidation resistance of coated GH4169 alloy is better than that of uncoated GH4169 alloy. The coating has three layers: a cellular dendrite outer layer, a planar YSZ interlayer, and an inner layer composed of Cr₂O₃ formed during laser cladding. After oxidation at 1000 and 1050 °C, as the oxidation time increases, the cellular dendrite outer layer becomes thicker, and the planar yttria-stabilized zirconia interlayer becomes thinner. Between the planar interlayer and Cr₂O₃ inner layer, an Al₂O₃ layer formed. Notably, cracks formed in the interface of Al₂O₃/Cr₂O₃ owing to their weak interface strength, which led to the failure of the composite coating.

To improve the hydrogenation and dehydrogenation dynamics of NdMg₁₂-type alloy, we replaced part of Mg with Ni in the samples and used the ball milling method to prepare NdMg11Ni+x wt.% Ni (x=100, 200) samples. The influences of milling duration and Ni content on the electrochemical and gaseous dynamics of the samples were studied in detail. Dehydrogenation activation energies of samples were calculated by using Kissinger and Arrhenius methods. The conclusions show that the dynamic properties of samples are significantly enhanced with the increase in Ni content. With the change of the milling duration, the gaseous hydrogenation rate and high rate discharging capability reach the maximal values. However, the dehydrogenation dynamics of sample alloys are always enhanced with the prolonging of milling duration. More concretely, prolonging milling duration from 5 to 60 h improves the dehydrogenation ratio of NdMg11Ni + 100 wt.% Ni alloy from 58.03% to 64.81% and that of NdMg11Ni + 200 wt.% Ni alloy from 62.20% to 71.59%. Besides, the enhancement of gaseous hydrogen storage dynamics of the samples is believed to be the result of the declined dehydrogenation activation energy resulted from the increase in milling duration and Ni content.