熟妇熟女乱妇乱女网站_噼里啪啦免费高清看_av中文字幕一区二区_欧美日韩国产激情_热久久国产_另类视频在线观看_人人爱人人澡_一本黄色片_精品一区电影_亚洲第四页_爱情岛亚洲首页论坛小巨_婷婷丁香色_中文字幕一二区_麻豆传媒一区二区_国产在线网址

This paper systematically summarizes the development history and current situation of China’s titanium industry from the aspects of titanium resource distribution, production and processing, application fields, and distribution pattern of related enterprises. The paper analyzes the current problems of overcapacity and imbalance between supply and demand, the urgent need to optimize industrial structure, the insufficient linkage between upper design and lower industry, the urgent need for technological innovation and industrial upgrading, the dual challenges of resource and environmental constraints, and the dilemma of intensifying competition in domestic and foreign markets. The suggestions and prospects of optimizing cost structure and expanding application field, establishing a new collaborative mechanism of high-quality utilization of titanium materials and a cross-regional innovation platform of high energy level, guaranteeing incentive system to strengthen cooperation mechanism and play the role of strategic hinterland are put forward for the development of titanium and titanium alloy industry in Sichuan and Chongqing region.

Vanadium and chromium commonly coexist in nature as associated minerals in vanadium-titanium magnetite, which presents a significant technical challenge for their efficient separation during resource extraction. In light of this issue, several commonly employed vanadium and chromium separation techniques in current vanadium extraction processes, such as chemical precipitation, ion exchange, and solvent extraction, have been systematically analyzed in terms of their advantages and existing problems during application. It was emphasized that the development of more efficient and economical vanadium and chromium separation methods remains a key focus of current research. Furthermore, future vanadium and chromium separation technologies should prioritize the research and application of environmentally friendly techniques to address the environmental issues, such as wastewater and waste residue, generated during the separation process, thereby enabling efficient, green, and sustainable production.

The acidic calcified vanadium solution from Pangang Xichang Vanadium Plant was the research object in this study. In response to its characteristics of low acidity, high vanadium content, and difficulty in impurities removal, an extraction process was adopted to specifically remove Mn²⁺, Ca²⁺ and Fe³⁺ cations. The main influencing factors of the extraction process were investigated. And the optimal extraction parameters were determined. The organic phase ratio was 20% P204+80% 260# solvent oil with a saponification rate of 100% using ammonium hydroxide. The extractant ratio was O/A=2:1 at the initial pH of vanadium solution of 2.9 for 5 minutes. Under the above conditions, the single stage extraction rate of Mn and Ca reach over 98%. After extraction, the Mn content drops to around 0.05 g/L, Ca, Fe and Al leves are below 0.1 g/L in acidic vanadium solution.

In view of the increasing environmental protection and energy saving requirements of vanadium extraction from stone coal year by year, a clean process for V₂O₅ extraction by atmospheric pressure wet method including water leaching, extraction separation, vanadium precipitation and calcination was developed. A stone coal mine in Yueyang, Hunan Province was used as raw materials in this paper. Using insulated humidity-concentrated H₂SO₄ maturation leaching treatment, and also investigated the whole process of extraction, back-extraction and product preparation. The test results show that the vanadium leaching rate can reach 87.8% under the following conditions: 98.3% of mineral size under 100 μm, 10% of water mixing, 18% of acid dosage, maturation temperature of 120 ℃, maturation time of 8 h, water leaching liquid-solid ratio of 2:1 and stirring leaching for 2 h at room temperature. With P204 extraction, the vanadium extraction rate was 98% after 5 single-stage extraction at pH=2.2, and the back-extraction rate of 4 stages could reach more than 99%. At the pH of 1.0 for vanadium precipitation and then multi-vanadate was calcined at 600 ℃ for 2 h, required V₂O₅ product met the requirements of national standards.

In the production process of titanium dioxide by sulfuric acid method, the selection of salt treatment agents has a significant impact on the surface properties of rutile titanium dioxide crystals. Thus it is necessary to carry out an in-depth study to reveal the differences in the surface properties of titanium dioxide caused by different salt treating agents. In this study, the differences in surface morphology, crystal surface defects, and surface hydroxyl groups of rutile samples treated with zinc-based salt and aluminium-based salt were investigated using SEM, XPS, and BET instruments, respectively. The results show that the aluminium salt-treated rutile samples present elongated shape and suffer from greater sedimentation resistance during the sedimentation process. Meanwhile, the aluminium salt-treated rutile samples have more crystal defects and surface hydroxyls on the surface than the zinc salt-treated samples, and also have more pronounced dissociative effects on water molecules, higher surface potential in the water-dispersed system, and are more capable of forming more stable dispersed systems.

The effect of pure Ti alloyed with different Ru content on the microstructure and electrochemical behaviour was studied for the need of further improvement in corrosion resistance and conductivity of titanium bipolar plates in proton exchange membrane water electrolysis environments. Results indicated that the α-Ti equiaxed grains were refined, the corrosion resistance was improved with the increase of Ru content. The Warburg impedance appeared in the low frequency region of impedance spectroscopy obtained at OCP. When the Ru content is below 0.08%, the passivation film formed by polarizing at 0.8 V vs Ref for 6 h exhibits p-type semiconductor behavior, and the conductivity remains constant.

Since the contacting ultrasonic detection results indicated some defects existed in a bar of Ti-6Al-4V alloy, researching work had been carried out using optical microscope, scanning electron microscope metallographic analysis, microhardness, energy spectrum, electron probe, backscatter electron diffraction and other characterization methods. And uncommon carbon enriched defect had been figured out. Flecks surrounded with α stable area were observed in the microstructure. Then, it was figured out that flecks were Ti₂C with ordered FCC crystal and the α stable area was hard α phase based on the chemical composition and crystallology analysis. According to the distribution characteristics of chemical elements, the defect source was presumed to be raw materials contaminated by elements rich in carbon and nitrogen. Micro cracks initiated at Ti₂C/α boundaries and grew into the α side in the hard α and Ti₂C regions during the forging. Micro cracks would break through the Ti₂C crystal bridges and merged into ultrasonically detectable macro crack defects at last.

Commercially pure titanium (CP-Ti) was successfully fabricated by 2 passes of equal channel double angular pressing (ECDAP) process under BC route. The electrochemical corrosion behaviors of CP-Ti before and after ECDAP were also tested and analyzed in a 3.5%NaCl solution. The variation laws of circuit potential, dynamic potential polarization curve, and electrochemical impedance were obtained. The microhardness of the deformed specimens was tested and analyzed. The result shows, compared to the original material, the ultra-fine crystalline pure titanium fabricated by ECDAP process has higher microhardness and better corrosion resistance. The microhardness (HV) of the 2-pass deformed sample reaches 157.4 with an increase of 20.6% compared to the original material. The open circuit potential value of the 1-pass deformed sample is higher than that of the original material and lower than that of the 2-pass deformed sample. During the anodizing process, the current of the deformed sample is more stable, and the passivation state is less likely to be destroyed. The polarization resistance results show that the 2-pass deformed sample has the highest polarization resistance, and the sample is less prone to pitting corrosion during the corrosion process. Compared to the deformed samples, the original material has more corrosion pits with larger and deeper sizes on the corrosion surface. The corrosion performance of ECDAP deformed specimens is better than the original annealed sample, and the 2-pass deformed sample shows the best corrosion resistance.

Pure titanium tubes with different cold rolling deformations were annealed at different temperatures (450、470、490 ℃) to investigate the influences of deformations and annealing temperatures on the microstructures, texture evolution and mechanical properties of tubes. It is shown that the microstructure of the cold-rolled tubes with small deformation contains a great amount of twins, which mainly consist of {

}<

compression twins and {

}

tensile twins. The grains in the cold-rolled tubes with the greater deformation were severely deformed, along with the reduction of twins amount which is dominated by compression twins. The microstructure of tubes with the large deformation shows a strong texture of <

>//AD, and the other tube with small deformation shows a basal bimodal basal texture. The recrystallization proportion of the pure titanium tube, which is more severely deformed, increases gradually with the increase in annealing temperatures and its ratio reaches 50.5% after 490 ℃ annealing. Meanwhile, the tensile strength of the strongly deformed tubes decreases dramatically after 490 ℃ annealing, with the weakening of the cold-rolled texture and intensifying of the bimodal basal texture. The microstructural change of seamless tubes with the small deformation is not obvious, with a gentle reduction of the tensile strength, and the texture changes gradually from the bimodal basal texture to <

>//AD texture with the increase in annealing temperatures.

Shape bending often occurs during the production process of titanium alloy bars, and thermal tension straightening is an effective straightening method. In this study, the thermal tension straightening model of TC4 bar was established by using the finite element simulation software ABAQUS. The influence of straightening process parameters such as straightening temperature, holding time and tensile elongation on the straightness and residual stress of TC4 bar was studied systematically. And the optimized straightening process parameters were obtained combined with the physical experiment of straightening. The results show that the higher the straightening temperature, the longer the holding time and the greater the thermal tensile amount, the smaller the straightness and the smaller the residual stress of TC4 bar. In view of the actual production conditions, the optimal process parameters for the straightening of TC4 titanium alloy bar are determined with a straightening temperature of 750 ℃, a thermal tensile amount of 2% and a holding time of 10 s.

TC4 is a α+β duplex titanium alloy with low density, high specific strength, good weldability and corrosion resistance, which is widely used in weapons, aviation, aerospace, ships and orbits, and is one of the important materials for product lightweight. MIG-MAG welding was used to study the influence of welding current (80 ~ 300 A) on droplet transition and weld forming in this paper. The results show that with the increase of welding current, the transition mode changes from droplet transition to jet transition, and from one drop to multiple droplets in a pulse cycle, and finally forms a liquid column. The plasma flow force increases, the arc shape transits from bell shape to cone, and a finger-like penetration depth is formed in the center of the melt pool. The transition time is reduced, and the transition frequency is accelerated. When the welding current is 200 ~ 240 A, the droplet transition is uniform, the transition mode is the droplet transition. The arc is bell-shaped and the stiffness is good, the transition frequency is fast, the welding process is stable, the weld is well formed. The penetration depth and width are larger, the residual height is less, and the spatter is less, which is the recommended welding parameters.

The industrial technologies of tetragonal barium titanate mainly include solid-state method and hydrothermal synthesis method, but there are problems such as large particles, uneven particle size distribution, and low tetragonal phase content. Tetragonal barium titanate was successfully prepared by microchannel synthesis method using barium chloride, titanium chloride, and oxalic acid as raw materials, as well as compared with traditional co-precipitation method. The results of XRD, SEM and TEM indicate that the product is a high-purity, small particle size, and uniformly distributed tetragonal barium titanate, with an average particle size of 110 nm and a particle size distribution range of ± 16 nm. This method with simple synthesis process is easy to achieve mass production and lays the industrial production of high-purity and small-sized tetragonal barium titanate.

High-titanium blast furnace slag, as an ordinary industrial solid waste, is characterized by low activity and low utilization rate due to its high TiO₂ content and predominantly crystalline and stable mineral components, resulting in its accumulation. To better address the issues of low activity and utilization of high-titanium blast furnace slag, this review commences with an analysis of its powder properties and elaborates on four activation methods: mechanical activation, chemical activation, composite activation, and combined activation with other admixtures. The activation mechanisms of these four methods are also analyzed. Furthermore, the current research status and mechanisms of the influence of high-titanium blast furnace slag powder as an auxiliary admixture on the workability, mechanical properties, and durability of concrete are discussed. The environmental performance and economic benefits of high-titanium blast furnace slag powder are evaluated, and the shortcomings and future directions for enhancing its activity are pointed out. This study provides a reference for achieving better resource utilization of high-titanium blast furnace slag.

To improve the workability and mechanical properties of high titanium slag aggregate concrete, this paper proposed the use of magnetized water for its preparation. The study investigated the effects of different flow rates of magnetized water on the workability and mechanical properties of high titanium slag aggregate concrete, and conducted tests and analyses on its micro morphology and pore structure. The results show that magnetized water enhances the workability and strength of high titanium slag aggregate concrete and increases its air content. However, as the flow rate of magnetized water increases, the improvement effect diminishes. When the water flow rate is 40 mL/s, the slump, spread, 28 d compressive strength, and 60 d compressive strength are respectively increased by 9.5%, 14.9%, 8.9%, and 11.6% compared with tap water high titanium slag aggregate concrete. The microstructural test results indicate that the cracks between the aggregate and cement matrix of the magnetized water high titanium slag aggregate concrete are smaller, with more hydration products and fewer unhydrated cement and mineral admixtures, resulting in a higher degree of reaction. The "pinning effect" between the high titanium slag aggregate and the cement matrix is further enhanced. Additionally, the proportion of harmless pores is higher, and the proportion of harmful pores is lower, making the structure denser and thus stronger.

This study focused on a specific case - titanium concentrate from Panzhihua. Detailed process mineralogy research was conducted using chemical element analysis, AMICS, EPMA, XRD, SEM and optical microscope identification. The research reveals that the ilmenite concentrate contains 48.03% TiO₂ and 33.93% TFe, along with small amounts of impurity components such as MgO, SiO₂, Al₂O₃ and CaO. The primary mineral present is ilmenite (91.00%), followed by titanomagnetite (1.41%), with a small percentage (7.59%) consisting of gangue minerals including pyroxene, chlorite, titanite and olivine. The titanium element primarily exists in the form of independent mineral phases in ilmenite and titanite, with distribution rates of 99.50% and 0.35%, respectively. It also occurs as isomorphism in titanomagnetite, with a distribution rate of 0.12%. The theoretical TiO₂ grade of the titanium concentrate has been determined to be 52.09%. It is believed that part of the ilmenite and titanomagnetite in the titanium concentrate are formed by solid solution separation structures, which are difficult to effectively separate and eliminate using traditional beneficiation methods. Additionally, there are small amounts of gangue minerals containing impurity elements such as magnesium, calcium, silicon, and aluminum present in the titanium concentrate. These reasons render it challenging to enhance the grade of titanium concentrate. We ought to explore and optimize the beneficiation process for the purpose of effectively eliminating the gangue minerals within the titanium concentrate, thereby upgrading the grade of titanium concentrate and reducing the impurity content.

Batch grinding experiments of vanadium titanium-magnetite (VTM) with different grinding times before and after microwave treatment were carried out. The m-order grinding kinetics model of untreated and microwave treated VTM was established, and the effects of particle size and grinding time on the grinding speed were analyzed. In the initial stage of grinding, the number of microcracks was the main factor affecting the grinding speed. While in the middle and later stages of grinding, the grinding probability became the main factor affecting the grinding speed. The grinding speed of the coarse-grained (?3.350~+1.700 mm) ore after microwave pretreatment was much higher than that of the untreated ore, while the grinding speed of fine-grained (?0.057~+0.045 mm) ore changed slightly. Microwave assisted grinding of VTM is beneficial to improving the particle size composition of the grinding products, thus improving the separation efficiency and the concentrate quality.

In the process of continuous casting, the distortion of molten steel flow in mold caused by nozzle clogging is a key factor affecting the quality and production efficiency of castings. To solve this problem, a multi area controllable electromagnetic braking (MAC-EMBr) technology is proposed to improve flow state of molten steel and reduce negative impact of nozzle clogging. Firstly, a slab mold is selected as the research object to establish an analytical model of molten steel flow and steel-slag interface behavior in electromagnetic continuous casting mold. Secondly, the fluid-flow-related phenomena of three casting cases in the slab mold, i.e., No-EMBr, Ruler-EMBr, and MAC-EMBr, are further investigated numerically to evaluate the metallurgical capability of the MAC-EMBr, including the non-uniform flow characteristics of molten steel and the evolution pattern of steel-slag interface inside the mold. According to the simulation results, with a 25% blockage rate of a single-side nozzle, the braking effect of the Ruler-EMBr on the backflow in the upper region of the mold is not remarkably. In detail, when the magnetic flux density reaches 0.3 T, the maximum magnitude of the surface velocity and the maximum amplitude of the level fluctuation on non-clogging side with the Ruler-EMBr are 16.7% and 1.6% higher than those with No-EMBr, respectively. This is not conducive to the stability of steel-slag interface in the mold. However, under the same magnetic flux density as the Ruler-EMBr, the application of MAC-EMBr has great potential to suppress the upward backflow on the non-clogging side. In comparison with No-EMBr, the maximum magnitude of the surface velocity and the maximum amplitude of the level fluctuation with the MAC-EMBr are decreased by 16.7% and 48.4%, respectively. As a result, the flow of molten steel in the mold can be well controlled in different regions with the MAC-EMBr, so as to improve the symmetry of the flow field and reduce the flow asymmetry caused by nozzle clogging.

Rare earth Ce treatment is a hot topic in the modification of solidification microstructure for super austenitic stainless steel. In this study, the solidification phase structure, evolution of inclusions, and element segregation behavior of a 500 kg scale Ce-treated 7Mo super austenitic stainless steel were systematically analyzed, for the purpose of providing theoretical basis for Ce treatment of 7Mo super austenitic stainless steel. The results show that the non-equilibrium solidification path of 7Mo super austenitic stainless steel is L→L+γ→L+γ+δ→L+γ+δ+σ→L+γ+σ→L+γ+σ+Cr₂N. During cooling and solidification process, an intermediate phase δ phase exists, and the δ phase decomposes into σ phase and γ₂ phase at the end of solidification. The main second phase precipitated in the steel is the σ phase rich in Cr and Mo, resulting in a cast solidification structure composed of austenite and σ phase. After Ce treatment in super austenitic stainless steel, the inclusions in the ingot are mainly composite inclusions composed of AlCeO₃ and Al₁₁O₁₈Ce, with a low mismatch AlCeO₃ structure, which can serve as heterogeneous nucleation cores. During cooling and solidification process, the deoxidation ability of Al is enhanced, and the equilibrium of deoxidation reaction is broken, resulting in the generation of inclusions with Al₁₁O₁₈Ce encapsulating AlCeO₃ morphology. The microstructure of the ingot core is coarse, with severe microsegregation between dendrites. The size of micro grains is the key factor affecting the microsegregation between dendrites, and reducing the size of micro solidification structure grains can effectively improve the degree of element segregation inside the grains and then reduce Mo and Cr content in the σ phase between dendrites.

In order to calibrate the solidified end position of the 50CrV spring steel billet with 240 mm×240 mm section and determine the reasonable position of electromagnetic stirring at the solidification end, the nail shooting experiment was carried out on the Xianggang billet continuous caster. The results showed that the comprehensive solidification coefficient of the spring steel billet was 26.8 mm/min^1/2. When the casting speed are at 0.8 m/min and 1.0 m/min, respectively, The end positions of solidification are 16.2 m and 19.8 m from the meniscus surface, respectively, and the suitable positions of electromagnetic stirring at the end of solidification are 7.18 m and 8.84 m from the meniscus surface. Based on the verification of the nail test, the solidification heat transfer model was established, and had been used to studied the solidification characteristics of the casting billet under different continuous casting process parameters. The model predication could be used to optimize and correct the existing continuous casting parameters so that the electromagnetic stirring effect at the solidification end could be fully exerted and the central segregation should be reduced, consequently the quality of the casting billet could be improved.

The near-net forming process such as additive manufacturing provides technical paths for the preparation of complex parts of refractory high-entropy alloys, and also puts forward higher performance requirements for their powders. In this paper, the composition design criteria of refractory high-entropy alloys and the effects of various elements on the properties of alloys are reviewed. The main technical routes of powder preparation (mechanical alloying, plasma rotating electrode process and radio frequency plasma spheroidization) are analyzed and compared. In addition, the problems and solutions in the application of refractory high-entropy alloy powder in powder metallurgy, laser cladding, additive manufacturing and other fields had also been discussed.

Inclusions in superalloys are the main factors affecting the metallurgical quality and performance of the alloys. The control methods of inclusions in the vacuum induction melting process of GH4169 had been investigated from two aspects: melting process and raw material. Firstly, three batches of GH4169 were melted in a 12-ton vacuum induction furnace with highly consistent charging but different refining temperature at 1530, 1560℃, and 1590℃. The results showed that as the refining temperature increased, the erosion-reduction reaction between the alloy melt and the MgO crucible became more intense, introducing non-metallic inclusions such as Al₂O₃ and MgAl₂O₄ into the alloy melt. The number density of non-metallic inclusions at the A-end of the induction ingot increased progressively, which were 83.716, 171.180/mm², and 204.927/mm², respectively. Therefore, low-temperature refining should be chosen to reduce inclusion content by more than 50%, with refining temperature at around 1525~1535℃, refining vacuum degree ≤ 1.0 Pa, and duration of 1.5~2.5 h. Secondly, low-temperature refining was selected to reduce the impact of refining process on inclusions, and the impact of raw material purity on inclusions was compared. The results showed that using higher purity raw materials such as Cr, Nb and Ti for melting can reduce inclusion content in the induction ingot by more than 30%.

The effects of Ca treatment and Ce treatment on the steel inclusions during the steelmaking process of Ce-contented NM450 steel were studied. The evolution process of inclusions in steel was analyzed by Scanning electron microscope-energy dispersive spectrometer ( SEM-EDS ) equipped with AZtecFeature automatic inclusion analysis module and Factsage thermodynamic calculation. After

% Ce treatment, the main inclusions in the molten steel are modified from xCaO·yAl₂O₃ into complex inclusions such as low melting point xCaO·yAl₂O₃·zCe₂O₃, CeAlO₃+xCaO·yAl₂O₃, CeAlO₃+xCaO·yAl₂O₃+CaS and low melting point xCaO·yAl₂O₃·zCe₂O₃ +CaS. About 53% of the inclusions in the steel were removed after Ce treatment for 20 minutes. [Ce] diffuses into xCaO·yAl₂O₃ to form low melting point xCaO·yAl₂O₃·zCe₂O₃ inclusions in the molten steel. xCaO · yAl₂O₃ in the molten steel reacts with [Ce] to produce CeAlO₃, which in turn generates CeAlO₃+xCaO · yAl₂O₃ inclusions. After the secondary Ca treatment, the Ce inclusion species did not change. Although some of the inclusions were converted into liquid inclusions, the overall number of inclusions increased, and CaS became the dominant inclusion. It indicates that there is a problem of excessive calcium treatment in the current Ce treatment combined with double Ca refining treatment processes.

Creep damage equation construction and finite element simulation were used to analyze the high temperature creep behavior of GH3128 alloy at 950 ℃. Firstly, the creep damage equation was constructed by combining the K-R model, the Sinh model and the Liu-M model. Then the life prediction and damage behavior of the model were compared and analyzed. It is found that the maximum relative error of life prediction under 100, 90 MPa and 80 MPa is only 10.8%. The cumulative relative error of the Sinh model was the smallest with the value of 18.3%. The comparison of damage behaviors shows that the damage evolution processes of the Sinh model and the Liu-M model are slower than that of the K-R model, which is beneficial to the meshing in finite element simulation. Therefore, it is concluded that the Sinh model has the best prediction effect on the creep behavior of GH3128 alloy. Finally, the Creep subroutine interface in ABAQUS software was used to program the Sinh model through secondary development. The results of finite element simulation showed that the Sinh model was relatively accurate and efficient in analyzing the creep behavior of GH3128 alloy.

The microstructure and mechanical properties of the newly developed HB550 low-alloy high-strength wear-resistant steel were studied through optical microscope, scanning electron microscopy, tensile tests, and Vickers hardness tests. Meanwhile, the sliding wear behavior and the friction coefficient of high grade HB550 martensite wear-resistant steel under the loads of 10, 50 N and 90 N were systematically investigated by ML-100C wear testing machine and BMT-I multifunctional material surface performance tester, respectively. The results show that the microstructure of HB550 low-alloy high-strength wear-resistant steel was mainly tempered martensite. The mean yield strength and tensile strength as well as low temperature impact energy at ?40 ℃ with 5 mm thickness of this steel were 1521 MPa, 1874 MPa and 18 J, respectively. Moreover, with increasing the load, the wear mass loss of HB550 steel increased first and then decreased, while the friction coefficient decreased monotonously. The wear mechanism of the developed steel grade HB550 under lower loads is mainly abrasive wear and adhesive wear, and the wear mechanism under high loads is mainly adhesive wear accompanied by oxidative wear. The research results provide a theoretical basis for the development and application of high-end wear-resistant steel HB550 and above.

In this study, different contents of micro-alloying elements Nb and V were added to X80 pipeline steel. OM, SEM and TEM were used to observe the microstructures and precipitates. Tensile tests and Charpy tests were conducted to obtain the mechanical properties. Thermo-calc software was used for phase transformation calculation. The results showed that after reducing the Nb or V contents in the tested steel, the ratio of solid solution strengthening of the steel decreased; the volume fractions of the nano precipitates increased; the average diameters of the nano precipitates decreased; the ratio of precipitation strengthening of the tested steel increased; and the ratio of grain refinement strengthening of the steel was not obvious. Finally the strength of the tested steel was reduced, while the impact energy at -20 ℃ was significantly increased. This research has confirmed that adding appropriate amounts of 0.02%Nb and 0.04%V elements can improve the strength and toughness matching of materials.

This research is to investigate the mechanical properties of different carbon steel materials at different temperatures. The simulation model was established by using molecular dynamics, and the regression model was established by the three-factor multi-level orthogonal test and response surface method to study the effects of C content, vacancy ratio and temperature on Young’s modulus and yield strength. Under the same C content and vacancy ratio conditions, 50 models were established by using the random function of Matlab, and each test condition was simulated 50 times. The median of Young’s modulus and yield limit were used as key parameters of the mechanical properties of the reaction materials, and the response surface regression model was established. By randomly selecting 10 groups of simulation experiments, this study successfully explored the influence of different factors on the mechanical properties of carbon steels, obtaining a reliable mathematical model of materials mechanical parameters, and optimizing the composition of materials.

A low-cost 780 MPa grade cold-rolled dual phase steel with high formability was designed and developed based on the equipment characteristics of the production line, and the effects of continuous annealing on the microstructure and properties of the cold rolled products were studied. The results show that under different annealing conditions, the microstructure of the experimental steel is mainly composed of ferrite, dispersed bainite, martensite, and a small amount of M/A islands. Increasing the end temperature of rapid cooling can increase the retained austenite content, with the highest content of retained austenite reaching 3.9%. The retained austenite is mostly distributed in the form of thin films or blocks at the interface between B/F and F/F or B/M phases, and the retained austenite exerts the TRIP effect to achieve plasticity improvement.

In order to achieve the goal of enhancing the pulverized coal injection (PCI) rate, along with its stability and uniformity in vanadium-titanium blast furnaces, ultimately reducing energy consumption, a pilot-scale experimental device was developed, equivalent in scale and capacity to a

m³ blast furnace PCI system. Using this setup, the effects of various PCI processes and control parameters - including the secondary air injection ratio, the ratio of pressurized to replacement air, fluidization velocity, and discharge modes-on improving the injection rate, solid-gas ratio, and overall stability had been investigated. The experimental results revealed that, with a constant total gas flow in the injection pipeline, a decrease in the secondary air injection ratio led to a significant increase in both the injection rate and solid-gas ratio, as well as reduction in stability. When the secondary air injection ratio was maintained around 45%, the PCI rate and solid-gas ratio peaked, achieving the highest energy-saving potential. Furthermore, as the ratio of pressurized to replacement air increased, the PCI rate initially rose and then declined, reaching its maximum when the ratio was controlled between at 1.5~2. Similarly, the optimal bottom fluidization velocity was identified as 0.02~0.025 m/s, maximizing the injection rate, solid-gas ratio, and stability. Comparative analysis of two discharge modes (top discharge and bottom discharge) indicated that the top discharge mode offered superior stability due to the agreement of the gas flow direction with the discharge direction.