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Studies show that manganese sulfide (MnS) inclusions in pipeline steel affect the lateral performance of steel in its rolling deformation, as well as the hydrogen-induced cracking and sulfide stress corrosion cracking resistance performance. To inhibit the precipitation of MnS and its effect on pipeline steel, a quenching experiment and a diffusion couple experiment, which investigated the evolution of MnS inclusions in Ti-bearing X80 pipeline steel, were conducted. The experimental results show that the transformation of the MnS inclusions during solidification is as follows: MnS→titanium sulfide (TiS)→Ti4C2S2. The transition temperatures of MnS to TiS and TiS to Ti4C2S2 are 1673 and 1273 K, respectively, and the overall size of the sulfide decreased as well. Thermodynamic calculation results confirm that the transition temperatures of MnS to TiS and TiS to Ti4C2S2 are 1623 and 1203 K, respectively. When the sulfur content in the X80 pipeline steel is 0.001 5%, all the sulfur in the steel can be converted into Ti4C2S2 with a titanium content of more than 0.02%.

A mathematical model was developed to investigate the effect of snorkel shape on the recirculation rate and the erosion of the lining refractory during RH degassing process. A particle image veloci...

To clarify the influence of FeO and sulfur on solid state reaction between an Fe−Mn−Si alloy and MnO−SiO2−FeO oxides under the restricted oxygen diffusion flux, two diffusion couples with different sulfur contents in the oxides were produced and investigated after heat treatment at 1473 K. The experimental results were also compared with previous work in which the oxides contained higher FeO. It was found that although the FeO content in the oxides decreased from 3wt% to 1wt% which was lower than the content corresponding to the equilibrium with molten steel at 1873 K, excess oxygen still diffused from the oxides to solid steel during heat treatment at 1473 K and formed oxide particles. In addition, increasing the sulfur content in the oxides was observed to suppress the diffusion of oxygen between the alloy and the oxides.

A new method using a confocal scanning laser microscope for melting oxide at 1673 K (1400 °C) to produce a diffusion couple, which consists of oxide and an iron-based alloy, has been developed for the investigation of a solid-state reaction between them. It is important to obtain good contact between the Fe-Mn-Si alloy and MnO-SiO2-FeO oxide before the diffusion experiment to observe diffusion of elements between them at 1473 K (1200 °C). In this system, the melting point of the oxides is higher than the temperature where the reaction would be observed. The pretreatment involving melting oxide at 1673 K (1400 °C) to obtain good contact with the alloy was carried out using a new method. The effect of the pretreatment at 1673 K (1400 °C) on the diffusion experiment at 1473 K (1200 °C) was minimized by this new method. The effect of diffusion of oxygen on the solid-state reaction between the Fe-Mn-Si alloy and MnO-SiO2-FeO oxide at 1473 K (1200 °C) was observed clearly and showed good agreement with Wagner’s model of internal oxidation of metal.

Magnesium oxide (MgO) based refractories are widely used in secondary refining processes, and their dissolution into refining slag is the primary cause of their shortened lifespan. The dissolution rate was investigated for sintered MgO and commercial MgO–C and MgO–Cr2O3 refractories in a synthesised 50CaO–45Al2O3–5SiO2 liquid (mass-%) slag. The change in slag composition was measured after a refractory sample was placed into the molten slag that was stirred by flowing argon gas at 1773 K. The dissolution rate of the sintered MgO was above those of the MgO–C and MgO–Cr2O3 refractories under the same gas flowrate, although the dissolution rate of all samples increased as the gas flowrate was increased from 25 to 75 mL·min− 1. The slag containing 5 mass-% FeO considerably promoted the dissolution of the MgO–C refractory because of the oxidation of carbon by FeO. The dissolution of all the refractories was greatly affected by penetration of the liquid slag, with the mass transfer of MgO in the penetra...

On the basis of the existing originally modified calculation models of theoretical combustion temperature (TCT), some factors, such as the combustion ratio of pulverized coal injection (PCI), the decomposition heat of PCI and the heat consumption of SiO2 in ash reduced in high temperature environment, were amended and improved to put forward a more comprehensive model for calculating TCT. The influences of each improvement on TCT were studied and the results were analyzed compared with those of traditional model and originally modified model, which showed that the present model could reflect the thermal state of a hearth more effectively.

The mathematical model of minimum safety factor that investigated the collapse trends of coke layer under different charging parameters was established firstly on the basis of the slope stabilization theory in soil mechanics, and then the model of burden profile after coke collapse was improved by adopting the predetermination of quadratic curve and energy correction methods. The research will provide theoretical evidences for describing the coke profile more accurately and technical direction for choosing suitable charging parameters of blast furnace. The results show that: it is helpful to improve the stability of coke layer with increasing chute inclining angle and length of the coke flat; when the main falling point of ore moves toward furnace wall or the coke flat is wider, the curve radian of burden profile after coke collapse becomes smaller; the ore to coke ratio distribution agrees with the gas top temperature measurement well under considering coke collapse comparing with the result of ignoring coke collapse.

The reduction degradation characteristics of typical sinter, pellet and lump ore were tested with the reducing gas conditions simulating two kinds of iron-making processes. The results show that, in the same condition of gas composition and temperature, the reduction degradation degree (RDI