Applied Mechanics and Materials Vols. 217-219

Abstract: Effect of phosphorus content on the mechanical properties and microstructure of IF steel sheets was investigated. Average grain size and recrystallization texture were measured by electron backscatter diffraction (EBSD). The results showed that the higher P resulted in higher tensile strength and lowered the elongation and r-value. The average grain size increased with decreasing P content. The //ND (γ-fiber) pole intensity had a lowest value for IF steel with the highest P content which in turn deteriorate r-value. The element P played an important role in recrystallization process which affected the mechanical properties and microstructure of IF steels.

Abstract: The current development of derect reduction technology for rotary hearth furnace (RHF) is introduced. It is essential to stable and continuous operation of the RHF carrying out the following technologies: the cold-pressing technology，design of the charging machine and discharging machine of the RHF, temperature, pressure and atmosphere in the furnace, and the antioxidation of the metallized pellets. The current develop situation of these technologies are fully discussed.

Abstract: Through carrying out large scale of experiments, the process of ‘rotary harth furnace direct reduction—deep reduction electric arc furnace—extracting vanadium from vanadium bearing slag—extracting titanium from titanium bearing slag gets through and the recovery of Fe, V and Ti reached 90.77%, 43.82% and 72.65% respectively. With the study on the laboratory experiments and industrial tests, the bottlenecks of this technology such as low metallization rate of vanadium-titanium magnetite in direct reduction process, low reduction rate of vanadium in EAF, vanadium-recovery of hot metal with high silicon content, titanium-recovery of high –Mg &Al slag with titanium, and so on, have been solved. Based on this, the metallization rate of vanadium-titanium magnetite in direct reduction process is more than 90%, reduction rate of vanadium in EAF deep reduction process is more than 80%, vanadium-recovery rate in slag is more than 65%, and titanium-recovery rate in slag is more than 75%. That means good study results have been gotten. Furthermore, low-carbon pig iron with good quality in EAF steelmaking are gotten. Otherwise, V₂O₅ sheet and titanium products can meet the requirements of GB3283-87 and PTA121, respectively.

Abstract: The erosion of the lining refractory of the deep reduction electric arc furnace is introduced, and the erosion appears in the process of smelting metallized pelltes produced by vanadium titanium magnetite. It shows that arc erosion, chemical erosion of oxides in slag, slag basicity, as well as joint and crack of brick are the main reasons of the serious erosion of the refractory through the analysis.

Abstract: To develop the desulphurization technology for electric steel, desulfurizer using for electric steel in RH refining process has been studied. Meanwhile, key technologies such as converter end-point control, modification of ladle slag in secondary refining process, as well as desulphurization technology in RH refining process are studied deeply. Industrial tests show that desulphurization rate in RH refining process is as high as 28% for electric steel, and the ratio which sulfur content below 0.005% is as high as 70%.

Abstract: In order to promote the fusion of lime in semi-steelmaking, fluorite was used in converter steelmaking to improve the melting slag ratio, while fluorite is very harmful. In order to make best use of the metallurgical slag and improve the scorification problems in semi-steelmaking, PANGGANG Research Institute developed a new type high alumina composite slag, and accomplished industrial application which also achieved good results. They found that this new type slag can improve the melting slag ratio greatly and decrease the times of “re-drying” and “slopping” throughout the converter steelmaking, the slag sate can be good controlled, at the same time the content radio of TFe decreased significantly.

Abstract: An orthogonal cutting model was presented，and the cutting process was simulated by a finite element software based on the thermal-elastic-plastic FEM theory and updated Lagrange method.We obtained the distributions of residual stresses in machined layer of NAK80 mold-steel.The effects of cutting speeds，cutting depths and tool geometry on residual stress distributions were investigated. Comparing to experimental results，the conclusions are more accurate.

Abstract: Ultrasound-assisted electrospark deposition (UAESD) is an electrospark deposition (ESD) technology combined with ultrasonic vibration. In this paper, the effect of main process parameters, including discharge voltage, discharge frequency and specific deposition time, on depositing thickness and strength for 3Cr2NiMo die steel are experimentally studied and compared between the UAESD and the ESD process. The results show that the depositing thickness decreases between 28% and 53% while the depositing strength increases under the influence of the ultrasonic vibration.

Abstract: The mechanical properties and microstructure of the high strength low alloy HC340LA were obtained with different strain rate. The research shows that the better plasticity, higher tensile strength and yield ratio can be found in high speed tensile state than in quasi-static tension. The plasticity and tensile strength decrease with the increasing of the strain rate during the high speed tension. With the increasing of the strain rate, the grain size of the ferrite decreases and its distribution is uneven, and the grain boundaries increases. The HSLA steel HC340LA submit to obvious Ductile Frecture mechanism. The size of the dimples is more uniform, bigger and deeper with the strain rate 50 s^-1 than with the strain rate 200 s^-1. Therefore, the higher strain rate with over strain rate 50 s^-1 has less ^{Superscript text}contribution to the improvement of plasticity of the HSLA steel HC340LA.

Abstract: The multi-pass compression deformation of low carbon bainitie steel was carried out on a thermal simulator between a temperature range of 1050~800°Cwith accumulated 60.7% deformation and a deformation rate of 2s-1. The recrystallization behavior of the tested steel during high temperature deformation was discussed after comparatively analyzing the stress-stain curves and austenite deformation structures under different deformation conditions. The results show that with the same strain rate and total deformation, the grain size of recrystallized austenite is mainly determined by pass temperature and pass deformation, especially the latter, while has little relation with quantity of pass. The ultimate deformation stress is determined by ultimate deformation temperature and improved by the increasing quantity of pass.