The strength of Q690DR steel decreases with the increase of tempering temperature, and the -40 ℃ impact toughness increases with the decrease of quenching temperature, and the increase of tempering temperature between 640-680 ℃. Controlling the heat treatment condition, it can ensure the steel meets engineering application requirements for new high-pressure hydrogen storage vessels. Through the slow strain rate tensile test with electrochemical dynamic hydrogen charging, the elongation rate of Q690DR was reduced by 3%, and the area shrinkage was reduced by 14.1%, compared with the tensile test results under air condition. It showed that Q690DR has a low susceptibility to hydrogen embrittlement under such condition. The hydrogen desorption curves of Q690DR under different heating rates, placement times, and hydrogen charging current densities were tested through thermal desorption sepctrometry TDS. The low-temperature hydrogen desorption activation energy of Q690DR was calculated to be Ea=13.39 kJ/mol, and the high-temperature hydrogen desorption activation energy of Q690DR was calculated to be Eb=117.51 kJ/mol. The hydrogen diffusion coefficient of Q690DR is 9.85×10^-7 cm²/s. After hydrogen charging, the diffusible hydrogen in the matrix can escape completely after being holding for more than 12 hours. The hydrogen content charged in the Q690DR matrix increases with the increase of hydrogen charging current density. In addition, with the help of atomic force microscope AFM, we observed the enrichment behavior of hydrogen in the grain boundaries and the second phase after hydrogen charging. Based on the changes in potential difference, we can judge that the grain boundaries are shallow hydrogen traps and the second phase is deep hydrogen traps.

With the rapid progress of China′s power electronics and new energy industries, the demand for efficient, multi-purpose and environmentally friendly soft magnetic alloys is also gradually increasing. Existing research situation on the performance regulation of silicon steel is discussed. Based on the characteristics of the soft magnetic material, we points out the core performance index of iron loss, and points out the necessity of improving the resistivity of the material through composition regulation and other means, so as to achieve the maximum energy efficiency. Secondly, the influence of alloy composition, inclusion, defect, grain size, residual stress and crystal structure on the performance of silicon steel is discussed. In addition, we points out that with the progress of material science and nanotechnology, the research on the relationship between microstructure and performance of silicon steel will be more in-depth, and people will be able to more precisely regulate silicon steel in order to achieve better magnetic performance.

Refining grain size can effectively enhance the coercivity of bulk sintered NdFeB permanent magnets while ensuring high uniformity in magnetic properties. Key steps for grain refinement in sintered NdFeB magnets and current industrial equipment status had been described. During rapid solidification, high cooling rates effectively suppress α-Fe phase formation and reduce fragmentation difficulty. For cerium-rich magnets, trace additions of co-associated rare earth elements like La and Y help decrease the growth width of rapidly solidified flakes. Quantification of liquid volume per unit time during production proves crucial for structural consistency in rapid-solidified products. In powder preparation, regulation and adaptive control of hydrogen decrepitation process achieve preliminary powder refinement. Different jet mill configurations exhibit distinct characteristics, with fluidized bed jet mills being the most prevalent equipment, where airflow velocity at nozzle intersections in grinding chambers determines powder refinement efficiency. Regarding sintering, beyond conventional processes, spark plasma sintering emerges as an effective approach for achieving densification and suppressing abnormal grain growth. For powders with particle sizes below 2 μm, pressureless forming technology successfully resolves the forming challenges inherent to ultrafine powders.

High purity dysprosium and terbium metals serve as the fundamental raw materials in various fields, including permanent magnet materials, magnetostrictive materials, magneto-optical storage materials, magnetic refrigeration materials and electric light source materials. The calcium thermal reduction method and the intermediate alloying method used in the preparation of industrial pure dysprosium and terbium metals are summarized, and the vacuum distillation method, zone melting method and solid state electromigration method are described in detail. The technology of hydrogen ionization arc melting, electrochemical deoxidation and solid phase external inspiratory are also summarized. Finally, we considers the future development direction of high purity dysprosium and terbium metals from the perspective of market orientation and operability, and provides reference for the development of high purity rare earth metals dysprosium and terbium industries.