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.

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.

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 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.