11 results about "Intergranular fracture" patented technology

The invention relates to the technical field of heat treatment of steel for high-performance heading machine tools, and discloses an ultra-fine grain solid-phase regulation and control process for improving the structure uniformity of alloy steel, which comprises the following steps: collecting electrical parameters of an induction loop and identifying sudden change of parameters of a phase change point to determine a phase change leading edge position; triggering pulse disturbance heating at a preset depth to generate transient volume dislocation stress, breaking core carbide segregation and driving stress extreme values to gather towards the center; controlling the temperature rise rate to make the nucleation rate higher than the diffusion rate so as to form a dispersed crystal nucleus; according to the method, the phase change transient volume dislocation strain field is used for blocking the continuity of the net-shaped hard and brittle phase, the structure heredity of the large-scale section steel is eliminated, the total cross-section structure is highly homogenized, equiaxed crystals are ultra-refined, and the intergranular fracture resistance of the material in the service environment is enhanced.

This disclosure provides a process for preparing fine-grained nickel-titanium shape memory alloy rods for medical use, comprising: forging a heated nickel-titanium alloy ingot through multiple passes, performing multiple high-temperature continuous rolling passes, and then performing thermomechanical treatment to obtain fine-grained nickel-titanium shape memory alloy rods. This invention, through a combination of specific multi-pass forging and strictly temperature-controlled high-temperature continuous rolling, utilizes a robust dynamic recrystallization mechanism to fundamentally refine and homogenize the austenitic matrix grains, and completely breaks down the continuous brittle Ti2Ni phase distributed along the grain boundaries into a randomly dispersed distribution, thereby obtaining fine-grained nickel-titanium alloy rods with high purity and excellent microstructure. This solves the practical problems caused by the coarse grains and brittle phase segregation of the original cast nickel-titanium alloy, such as easy intergranular fracture, difficult processing and forming, low yield, and poor fatigue life in medical applications.

The invention discloses an annular sample for preparing an intergranular fracture, a heat treatment method of the annular sample, a preparation method of an intergranular fracture sample and the intergranular fracture sample, and relates to the technical field of materials, the inner diameter of the annular sample is D0, the width of the annular sample in the axial direction is h, and h / D0 is larger than or equal to 0.2 and smaller than or equal to 0.6. Through the short and thick annular sample, h is obviously smaller than D0, after knocking, a plane section can be obtained, the section is basically parallel to the axial direction of the sample, the along-crystal section can be shot by directly clamping the sample in the axial direction, the time cost for obtaining the along-crystal fracture is reduced, and the quality of the along-crystal fracture is improved. When h / D0 is smaller than 0.2, the problems that the radial length of a circular ring is too short, the effective sectional area of a fracture fragment is too small and the fracture shooting efficiency is low exist, and when h / D0 is larger than 0.6, the problems that the radial length of the circular ring is too long, the breaking operation is inconvenient and the fracture of the formed fragment is irregular exist. And shooting is inconvenient when the fracture is placed into a scanning electron microscope.

The invention belongs to the field of mechanical property test and evaluation of metal materials, and discloses a method for judging the tensile fracture quality of a hot-rolled steel plate. The method comprises the following steps: acquiring a sample with the special fracture; whether yield and necking phenomena occur or not before fracture is confirmed, and mechanical property data are obtained; comparing the performance data with a qualified reference sample; if it is confirmed that yield necking occurs and no significant difference exists in performance, it is directly judged that normal ductile fracture occurs; if the performance difference is obvious, microscopic morphology observation is carried out, and if dimple characteristics are observed, normal ductile fracture is still judged; if yield necking does not occur, microscopic observation judgment is performed, and if cleavage or intergranular fracture characteristics are observed, brittle fracture is judged. According to the method for judging the tensile fracture quality of the hot-rolled steel plate, normal special fractures and material defects of high-strength steel can be quickly and accurately distinguished, unnecessary microscopic reinspection is avoided, judgment standards are unified, quality disputes can be reduced, and material application is promoted.

The application belongs to the technical field of aero-engines. A thermal shock test method and test device for evaluating flame tube life parameters are disclosed. The test object in the method is a flame tube. Compared with whole machine level life examination, only the requirements and conditions of the flame tube test need to be considered, the requirements and conditions of components unrelated to the flame tube can be reduced, and the test operation is simplified. The failure mechanism (intergranular fracture or transgranular fracture) of the flame tube and the thermal shock cycle spectrum (triangular cycle or rectangular cycle) are determined by using the working condition, so that the flame tube life test acceleration processing can be realized. By flexibly adjusting the temperature of the main road gas and the impact gas, different gas environments can be simulated, the flame tube wall temperature of different working conditions can be achieved, the investigation of the alternating stress of the flame tube under high temperature creep and low cycle can be realized, and a method for considering the actual working gas environment and evaluating the flame tube life at the component level is provided.

The present invention provides a high-strength hydrogen-embrittlement-resistant stainless steel, comprising, in percentage by mass: C: 0.1%-0.4%, Si: 0.2%-0.5%, Mn: 4.5%-5.5%, P≤0.01%, S≤0.002%, Cr: 0.6%-1.0%, V: 0.1%-0.2%, Nb≤0.08%, B: 0.001%-0.005%, and the balance being Fe. By adding Nb and V microalloying elements on an original stainless steel, austenite grains are refined, and a high-efficiency hydrogen trap is formed in a matrix, thereby improving the resistance of the steel to hydrogen-induced delayed fracture. The stainless steel is processed by means of a hot forming process. Once a steel plate has undergone isothermal annealing, a tempering process is added, the temperature and time of the tempering process are controlled, and finally quenching is performed. Brittle intergranular fracture in the obtained stainless steel is significantly reduced, and the hydrogen embrittlement susceptibility of the stainless steel is effectively decreased.

This invention discloses a crack-resistant nickel-based superalloy, its preparation method, and its applications, belonging to the field of nickel-based alloy technology. The crack-resistant nickel-based superalloy, by mass percentage, comprises: Cr: 12-18%; Co: 8-15%; Mo: 3-6%; W: 2-4%; Al: 1-3%; Ti: 2-4%; Ru: 0.5-2%; Y: 0.3-1%; B: 0.002-0.01%; with the balance being Ni and unavoidable impurities. This invention utilizes rare earth oxides to passivate aluminum, forming a Y₂O₃ passivation layer, effectively suppressing the precipitation of low-melting-point phases and significantly reducing the crack propagation rate under high-temperature cyclic loading. Simultaneously, it optimizes grain boundary bonding energy, improving the long-term service stability of the alloy under oxidative-thermal corrosion coupled environments. Through the Ni-B master alloy preparation process, using carbothermic reduction and liquid filtration technology, boron segregation and the formation of brittle borides are avoided, eliminating grain boundary stress concentration sources and ensuring uniform boron distribution in the matrix. This suppresses intergranular fracture tendency under high-temperature and high-stress conditions, extending the alloy's lifespan.

In a method for mineral comminution energy determination and intelligent liberation degree identification based on morphological characteristics of particles, magnetite ore is comminuted with a drop weight impact testing machine and then subjected to particle size classification. Liberation degrees of the comminuted particles of some particle size classes with small relative particle sizes when different comminution energy is applied are detected and recorded using a mineral liberation analyzer. Profiles of liberation degrees of different minerals are established according to the detected data. The profiles are analyzed to determine appropriate comminution energy E, and then the comminuted particles of the particle size classes with the comminution energy are scanned by an electron microscope to obtain electron microscope images. Proportions of intergranular fractures of the particle size classes are counted. Comminution energy E1 corresponding to the particle size classes is calculated based on a function.

The invention discloses a method for microwave-enhanced selective extraction of gallium from vanadium extraction converter sludge, and belongs to the technical field of metallurgical waste treatment. In order to realize low-energy-consumption and high-selectivity extraction of trace gallium in vanadium converter sludge, the invention provides a microwave-enhanced selective gallium extraction method, which comprises the following steps: pretreating vanadium converter sludge, and then mixing the pretreated vanadium converter sludge with a wave-absorbing tempering agent; and carrying out microwave irradiation treatment in a single-frequency microwave or power change microwave or multi-frequency microwave synergistic manner, and leaching to obtain the gallium-containing leachate. According to the method, on the basis of selective bulk phase heating characteristics of microwaves, different mineral phases are induced to generate intergranular fracture and microcracks due to mismatching of thermal expansion coefficients, so that efficient and selective extraction of gallium is realized under mild conditions, and particularly, the recovery rate is further improved through the synergistic effect of power change microwaves and multi-frequency microwaves.

The application provides a boron-doped molybdenum-tungsten refractory metal grain boundary purification method, and belongs to the technical field of powder metallurgy engineering. Pure boron, boric acid, molybdate and tungstate, rare earth nitrate and carbide are put into deionized water to prepare a solution or a suspension; then, the solution or the suspension is pre-frozen by liquid nitrogen and freeze-dried in a freeze dryer; the precursor powder is subjected to two-step calcination and two-step reduction; cold isostatic pressing is performed after ball milling; and finally, the boron-doped molybdenum-tungsten alloy is obtained through multi-step sintering in a reducing atmosphere. The composite powder obtained by the application has fine and uniform grains, the molybdenum-tungsten alloy sintered by using the composite powder has fine grain structure, high sintering relative density, and fine and dispersed carbide / oxide, and more importantly, the grain boundary of the boron-doped molybdenum-tungsten alloy is modified, the fracture morphology is changed from intergranular fracture to quasi-cleavage fracture, which helps to improve the low-temperature brittleness of the molybdenum-tungsten alloy and significantly optimize the room temperature mechanical properties of the molybdenum-tungsten alloy.

This invention discloses a method and system for controllable crack propagation in metal components based on fatigue guidance and real-time monitoring, belonging to the technical fields of metal material failure analysis, non-destructive testing, and structural safety assessment. Through fatigue-guided propagation, the crack separates slowly and stably at extremely low stress levels, avoiding macroscopic plastic deformation, impact damage, and instantaneous fracture zone impact caused by traditional overload fracture, perfectly preserving the original microstructures such as fatigue striations, cleavage planes, and intergranular fracture. By deploying monitoring sensors and using a crack state fusion solution model based on real-time data acquisition, the crack propagation rate is dynamically calculated, thereby adjusting the parameters of high-frequency, low-amplitude cyclic loading. This closed-loop feedback control mechanism can perceive the crack state in real time, ensuring stable crack propagation under fatigue mechanisms, creating a core condition for obtaining high-quality fracture morphology.