68 results about "Stress corrosion cracking" patented technology

The invention discloses a stress corrosion crack propagation simulation and prediction method and system based on a phase field method. The method comprises the following steps: constructing a stress corrosion dynamic evolution model based on the phase field method; the stress corrosion dynamic evolution model is a control equation set for coupling a displacement field, a material concentration field and a crack phase field to carry out stress corrosion cracking evolution; establishing a discrete numerical value format for analyzing the stress corrosion dynamic evolution model, and performing simulation program development of the stress corrosion dynamic evolution model based on an ABAQUS platform according to the discrete numerical value format; and acquiring a specific load working condition, and performing stress corrosion crack growth rate simulation prediction on the nuclear reactor primary circuit 690 alloy material under different working conditions based on a developed simulation program to obtain the crack growth rate. According to the invention, the phase-field function is introduced to describe the crack morphology to simulate the stress corrosion crack propagation, and the rule of the stress corrosion crack propagation of the primary loop 690 alloy under different working conditions is accurately simulated.

The invention discloses a method for predicting the service behavior of an oil and gas pipeline under a stress corrosion cracking condition, and belongs to the field of material performance analysis and prediction. Firstly, based on a convection diffusion equation, a real stress intensity factor of an oil and gas pipeline crack tip is used as an unknown quantity to obtain a stress distribution condition; then, applying boundary conditions and a crack propagation criterion in fracture mechanics, and performing preliminary calculation to obtain crack propagation behavior characteristics of the one-dimensional semi-analytical model; and finally, calibrating and calculating the diffusion coefficient of the material parameter in the one-dimensional semi-analytical model to obtain real full-life service time information of the oil and gas pipeline material. According to the method, the full-life behavior information of stress corrosion cracking can be quickly obtained, and a partial differential equation does not need to be solved; on the basis of fracture mechanics, the mechanism of repeated fracture and reconstruction of the passivation layer in the fracture process can be reproduced; the full-life service time of the oil and gas pipeline can be effectively predicted, and the parameter calibration method can be applied to other conditions and is wide in application range.

The invention relates to the technical field of pipe fitting welding, and particularly discloses an automobile air conditioner connecting pipeline welding method.The automobile air conditioner connecting pipeline welding device comprises a welding device, the welding device comprises a bottom plate and bearing pipes, the bearing pipes are symmetrically and fixedly connected to the upper surfaces of the two sides of the bottom plate, and sliding rods are symmetrically and fixedly connected to the upper surface of the middle of the bottom plate; the top of the sliding rod is slidably connected with a high-frequency vibration auxiliary welding gun. According to the bronze drum, the rare earth element cerium is added into the welding wire, a local dehumidification device is combined for use, the chloride ion corrosion problem of an automobile air conditioner pipeline in the marine climate environment is effectively solved, the cerium element reacts with invaded chloride ions to generate a stable cerium-chlorine compound protection layer, the corrosion path is blocked, and the corrosion resistance of the automobile air conditioner pipeline is improved. And meanwhile, the welding environment humidity is strictly controlled to be below 30% through the local dehumidification device, the condition that water participates in electrochemical corrosion is eliminated from the source, stress corrosion cracks are completely eliminated, and the durability of the welding structure in the coastal area is remarkably improved.

To provide forged material of aluminum alloy, the forged material enabling increase of strength and improvement of stress corrosion cracking resistance to be made compatible with each other.SOLUTION: Forged material of aluminum alloy 11 contains Mg:0.50 mass% or more and 1.25 mass% or less, Si:0.40 mass% or more and 1.40 mass% or less, Cu:0.50 mass% or more and 1.00 mass% or less, Fe:0.05 mass% or more and 0.40 mass% or less, and Ti:0.005 mass% or more and 0.10 mass% or less, contains at least one kind selected from Mn and Cr within the range of Mn:0.50 mass% or more and 1.20 mass% or less, and Cr:0.20 mass% or more and 0.33 mass% or less, and the balance consisting of Al and inevitable impurities. Further, an average value [ΔVmax average] of the maximum potential difference between a matrix and an Al-(Fe,Mn,Cr)-Si-based compound having a circle equivalent diameter of 1.0 μm or more is 144 mV or less.SELECTED DRAWING: Figure 1A

The invention discloses a method and a system for regulating and controlling residual stress of a high-strength aluminum alloy thin-wall ribbed member. The invention relates to the field of material processing, and aims to solve the problems that in the prior art, macro-micro coupling residual stress of a high-strength aluminum alloy thin-wall ribbed component is difficult to systematically and cooperatively regulate and control, and processing deformation, size out-of-tolerance and stress corrosion cracking are easily caused. The method comprises the steps that tensile preload is applied to the component, 0.2%-0.8% of global inelastic strain is generated, and unloading is carried out after load holding; high-frequency ultrasonic vibration is applied to the surface of the component, and the local alternating stress amplitude is not lower than 10% of the local residual stress value of a corresponding area; the lowest temperature is less than or equal to-150 DEG C, and the heating and cooling rate is controlled between 0.5 DEG C / min and 5 DEG C / min. After being treated by the method, the residual stress peak value of the component is obviously reduced, the dimensional stability is greatly improved, the microstructure is optimized, and the service performance is enhanced.

The invention relates to the technical field of alloys, in particular to a high-toughness corrosion-resistant industrial aluminum alloy for a new energy automobile and a preparation method of the high-toughness corrosion-resistant industrial aluminum alloy. According to the aluminum alloy, magnesium-lanthanum co-doped calcium-phosphorus particles are introduced to serve as a sacrificial phase, aluminum-zirconium and aluminum-erbium dispersed phases are combined to form a stable framework, and the solute cluster gradient is constructed in the thickness direction of a plate through a non-isothermal pre-aging process. The preparation method comprises the steps of intermediate alloy preparation, smelting and casting, homogenizing heat treatment, rolling, solid solution quenching, non-isothermal pre-aging and pre-stretching forming. The alloy is excellent in comprehensive performance, corrosion resistance and stress corrosion cracking resistance are remarkably improved while high strength and good bake hardening response are guaranteed, and the alloy is particularly suitable for new energy automobile body structural parts.

A kind of thick-wall acid-resistant pipeline steel X65MS hot rolling process method, the chemical composition of steel is as follows: C=0.03%~0.04%, Si=0.2%~0.4%, Mn=1.0%~1.2%, Cr=0.2%~0.4%, Cu=0.2%~0.3%, Ni=0.1%~0.4%, Mo=0.10%~0.25%, Nb=0.03%~0.04%, Ti=0.01%~0.015%, Ce=0.004%~0.006%, S≤0.004%, P≤0.008%, the balance is Fe and inevitable impurities;Production is carried out using continuous casting billet with thickness of 360mm and above, and the finished product thickness is 40~55mm;Three-stage rolling process and the matched intermediate billet cooling and post-rolling ultra-fast cooling process are used, the obtained pipeline steel has CLR≤10%, CSR≤1%, CTR≤1% in hydrogen-induced cracking (HIC) experiment under the condition of NACE solution immersion for 96 hours;In sulfide stress corrosion cracking (SSCC) experiment, no crack is found under the condition of four-point bending constant load nominal yield of 90% for 720 hours.

The present invention relates to martensitic stainless steel having high strength and hydrogen sulfide stress corrosion resistance, and a manufacturing method therefor. The martensitic stainless steel of the present invention has a high yield strength of 125 ksi or higher level (yield strength being greater than or equal to 862 MPa), also has excellent resistance to sulfide stress corrosion cracking (SSC), is suitable for a service environment having an H2S partial pressure of 0.1 bar, and still maintains good corrosion resistance in a high-concentration CO2 environment at a temperature as high as 177°C. The stainless steel of the present invention can be processed into a variety of product forms such as bars, plates, steel pipes, etc., and is widely applicable to application scenarios that have strict requirements on material strength and corrosion resistance, such as oil and natural gas production equipment and carbon dioxide capture, utilization and storage (CCUS) systems.

The application discloses a kind of based on residual stress threshold value corrosion cracking resistance heat treatment optimization method, belong to heat treatment numerical simulation research technical field, to solve the problem of high risk of stress corrosion cracking in weld heat-affected zone.Method includes determining the postweld residual tensile stress of inner wall weld heat-affected zone according to the cylindrical structure and physical properties of different materials;Four-point bending specimen is prepared, and target sample is prepared by annealing and bending moment loading;Residual tensile stress is loaded and finite element calculation is carried out for loading displacement;The residual stress threshold value of corrosion cracking is defined by electrochemical test on target sample;According to residual stress threshold value and combined with heating strip width basic formula, heat-mechanical coupling finite element simulation is carried out, and the optimized width correction coefficient is screened, to obtain the adaptive heating strip width design formula and complete optimization.The application can accurately determine the residual stress threshold value, optimize the heating strip width, improve the corrosion cracking resistance of component, and has economy and industrial value.

The invention relates to the technical field of sulfur-resistant drill rod testing, in particular to a method for preparing a uniaxial tensile sample for a sulfide stress corrosion cracking test, which comprises the following steps of: polishing the uniaxial tensile sample along the axial direction of the uniaxial tensile sample, so that axial scratches with uniform surface quality are formed on the polished surface; performing anti-hydrogen sulfide coating spraying treatment on the surface of the clamping section of the uniaxial tensile sample; the uniaxial tensile sample is polished in the axial direction of the uniaxial tensile sample, so that annular machining traces are avoided, meanwhile, the surface of the clamping section is subjected to hydrogen sulfide resistant coating spraying treatment, and breakage of the uniaxial tensile sample caused by surface quality defects such as transverse machining traces and transverse scratches in the scale distance and transition arc area is effectively avoided; and meanwhile, the risk of invalid fracture at the sealing part of the clamping section due to crevice corrosion is avoided.

To provide an ammonia stress corrosion cracking (SCC) acceleration test method capable of evaluating ammonia stress corrosion cracking sensitivity of a metal material with excellent accuracy in a short period.SOLUTION: In an ammonia stress corrosion cracking acceleration test method, a metal test piece to which external stress is added or which has residual stress is immersed in ammonium carbamate of 0.01 mass% or more and liquid ammonia containing O2 of 0.002 to 0.200 bar at a gas partial pressure, and is polarized to more than +1.0 V relative to corrosion potential.SELECTED DRAWING: None

The utility model relates to a furnace shell repairing structure of a blast furnace top combustion type hot blast stove, belongs to the field of ferrous metallurgy, and aims to solve the problem of cracking of a furnace shell in the using process of the top combustion type hot blast stove. According to the structure, a layer of outer layer furnace shell is welded outside a cracked furnace shell between a burner brick support and a combustion chamber brick support of the top combustion type hot blast stove, so that a new integral structure is formed. And a gap is reserved between the new outer-layer furnace shell and the original inner furnace shell, so that the air pressure borne by the hot blast stove and the gas sealing effect are met. According to the scheme, an outer protective layer is arranged outside the outer-layer furnace shell, so that the temperature of the outer-layer furnace shell is kept higher than the acid dew point temperature, and the influence of extreme climate on the furnace shell is reduced. Meanwhile, a device used for monitoring the displacement change of the inner furnace shell and the outer furnace shell is arranged on the outer furnace shell and used for judging the working state of the inner furnace shell and giving out early warning when the inner furnace shell fails. The scheme can effectively solve the general industrial problem of stress corrosion cracking of the furnace shell, and ensures the safe operation of the hot-blast stove.

The invention discloses a strengthening method and a preparation process of a high-strength corrosion-resistant aluminum alloy, and relates to the technical field of aluminum alloy materials.The strengthening method comprises the following steps that 1-3% pre-stretching treatment is conducted on a 7-series aluminum alloy profile obtained after solid solution quenching, and a dislocation network with the dislocation density larger than or equal to 10 < 14 > m <-2 > is introduced; by controlling specific chemical components of the 7-series aluminum alloy, a foundation is laid for high performance of the material, by means of a pre-stretching-aging synergistic process, residual stress is released through plastic deformation in pre-stretching, follow-up machining deformation and stress corrosion cracking risks are reduced, a dislocation network formed by pre-stretching provides a large number of uniform nucleation points for a strengthening phase, and the stress corrosion cracking risk is reduced. By combining two-stage aging and stretching regulation, uniform dispersed precipitation of a nanoscale eta'phase is promoted, generation of a thick eta phase is inhibited, meanwhile, the nucleation tendency of a strengthening phase at a grain boundary is reduced, a fine discontinuous grain boundary precipitated phase and a narrow lean solute region are formed, intergranular corrosion resistance and exfoliation corrosion resistance are remarkably improved, and balance of strength, toughness and corrosion resistance is achieved.

The invention discloses a method and device for determining the stress corrosion cracking risk of a pipeline and electronic equipment, relates to the technical field of petroleum and natural gas engineering, and aims to solve the problem of how to accurately determine the stress corrosion cracking risk of a target pipeline. The method comprises the following steps: acquiring material information and soil environment information of a target pipeline; determining a first evaluation parameter set based on the material information and the soil environment information; the first evaluation parameter set comprises an electrochemical parameter, a mechanical damage parameter, a crack propagation parameter and a fracture embrittlement parameter, and each evaluation parameter in the first evaluation parameter set is used for reflecting the risk state of the target pipeline; determining a second evaluation parameter set based on the first evaluation parameter set; and determining the stress corrosion cracking risk of the target pipeline based on the second evaluation parameter set. Therefore, the stress corrosion cracking risk of the target pipeline can be accurately determined, and safe and stable operation of the target pipeline is guaranteed.

The purpose of the present invention is to provide a stainless steel seamless pipe having high strength to ensure a yield strength of 758 MPa (110 ksi) or more, and also having excellent stress corrosion cracking resistance and local corrosion resistance.　The stainless steel seamless pipe has a specific composition, and a microstructure in which, in volume percentage, a martensite phase is 40% to 85%, a ferrite phase is 15% to 55%, and a residual austenite phase is 40% or less. In a cross section perpendicular to the pipe axis direction of the pipe, the variation coefficient of Cr is 6.0 or more, and the yield strength is 758 MPa or more.

The application discloses a zinc adding method for a pressurized water reactor nuclear power unit one-loop coolant, which comprises the following steps: during the zinc adding process, the zinc adding concentration is gradually increased while the zinc adding flow is kept constant. According to the zinc concentration monitoring result of the one-loop, the zinc adding method for the pressurized water reactor nuclear power unit one-loop coolant gradually increases the zinc adding amount in three stages; compared with the method of adding zinc at a high flow for the first time, the method can avoid the phenomenon that the zinc concentration of the one-loop instantaneously increases and the safety risk of fuel-related CIPS and CILC. On the premise that the zinc adding flow of the zinc injection metering pump is kept constant, the zinc adding concentration is gradually increased, and the method has the advantages of stable zinc adding flow and convenience for on-site implementation. The method can reduce the core radiation field of the unit in operation, relieve the stress corrosion cracking of the one-loop, ensure the fuel cladding integrity and avoid the safety risk of fuel-related CIPS and CILC.

The invention discloses a method for regulating and controlling stress corrosion cracking of microorganisms. The method comprises the following steps: preparing a U-shaped sample and calibrating a stress concentration area of the U-shaped sample; under the condition of constant culture medium volume, strain and inoculum size, constructing a biological membrane attachment area gradient by adding solid fillers with different specific surface areas; immersing the sample subjected to stress application into a culture medium, and enabling a stress concentration area to directly face the maximum attachment surface; after constant-temperature culture, corrosion indexes are detected, SEM is combined to observe crack morphology and XPS is combined to analyze product components, a quantitative relation of'biofilm attachment area corrosion rate crack propagation depth 'is established, and microbial stress corrosion behaviors are directionally controlled by regulating and controlling the attachment area. According to the method, the influence mechanism of biological membrane distribution on stress corrosion cracking of the material can be accurately analyzed.

The invention provides a method for determining the crack propagation rate of nickel-based alloy weld stress corrosion cracking, which comprises the following steps: S1, preparing a nickel-based alloy test plate with the same specification and welding process as an actual service component, and welding different areas on the nickel-based alloy test plate; s2, calculating an index n of a stress field intensity factor K; s3, calculating a CGR coefficient alpha and an index beta of HV or sigma s; s4, calculating activation energy Q; s5, a CGR model expression for unifying SCC of different areas of the nickel-based alloy weld joint is obtained; wherein CGR is the crack growth rate, HV is the Vickers hardness, and sigma s is the yield strength. The invention develops a new model for directly predicting the SCC CGR of each region of the welding seam according to the Vickers hardness (HV) or yield strength (sigma s) field test result of each region in combination with a stress field intensity factor (K). After the model is established, the CGR of the corresponding part can be obtained only by carrying out Vickers hardness or ball indentation test on different parts on site to obtain HV or sigma s, and data required by evaluation are more accurately and directly provided.

This disclosure provides a method for preparing a pre-grown film on the surface of a Zr-Ti-Ta alloy and the Zr-Ti-Ta alloy itself, relating to the field of alloy material preparation technology. The method includes: weighing composite Zr source powder, Ti powder, and Ta powder, and using them as raw materials for intermittent mechanical alloying; sequentially performing degassing and dehydrogenation, diffusion homogenization, and densification hot-pressing sintering; subjecting the α+β transition structure Zr-Ti-Ta alloy to phase stabilization heat treatment, cross-hot rolling, and recrystallization annealing; determining that the fine-grained single α-phase Zr-Ti-Ta alloy is within a constant potential pre-grown film window in the target medium; using the fine-grained single α-phase Zr-Ti-Ta alloy as a working electrode, immersing the working electrode in the target medium, defining the true potential of the working electrode relative to the reference electrode with a reference electrode, and ensuring that the true potential is within the constant potential pre-grown film window; and generating a dense barrier-type nanocomposite oxide pre-grown film containing ZrO2, TiO2, and Ta2O5 in situ on the surface of the fine-grained single α-phase Zr-Ti-Ta alloy. This disclosure can suppress localized anodic dissolution at crack tips and improve resistance to stress corrosion cracking.

The application relates to an in-situ stress corrosion monitoring system and a monitoring method, which comprises a stress measuring component, an electrochemical measuring component, a stress corrosion component and a control component. The electrochemical measuring component is used for placing a working electrode therein in the stress corrosion component and providing an electrochemical environment for the stress corrosion component; the stress corrosion component is used for corroding the working electrode under the electrochemical environment; the stress measuring component is used for stress testing of the corroded working electrode; and the control component is connected with the stress measuring component, the electrochemical measuring component and the stress corrosion component respectively and is used for controlling the work of the components. In the application, the test area is reduced through a slit, the test area is smaller than the crack width, the test precision of the stress corrosion cracking position is improved, and the X-ray focusing before the stress testing is timely carried out through the length-adjustable clamp base, so that the test speed is improved.

The application provides a method for calculating stress corrosion cracking failure probability and confidence interval of a pressurized water reactor primary circuit component, which can quantitatively predict the stress corrosion cracking failure probability of the structural material of a pressurized water reactor primary circuit device, provides a reference for the maintenance of the device, and has a wide application prospect; meanwhile, the method has a simple process, high calculation efficiency, is suitable for engineering application, and is beneficial to improving the safety and economy of the pressurized water reactor nuclear power plant.

The present invention relates to a thick steel material suitable for use in applications such as line pipes and sour-resistant materials, and more particularly to a high-strength steel material that has excellent resistance to sulfide stress corrosion cracking and excellent resistance to the propagation of sulfide stress corrosion cracking, and a method for producing the same. [Solution] The steel material of the present invention contains, by weight, carbon (C): 0.02-0.06%, silicon (Si): 0.1-0.5%, manganese (Mn): 0.8-1.8%, chromium (Cr): less than 0.05%, phosphorus (P): 0.03% or less, sulfur (S): 0.003% or less, aluminum (Al): 0.06% or less, nitrogen (N): 0.01% or less, niobium (Nb): 0.005-0.08%, titanium (Ti): 0.005-0.05%, calcium (Ca): 0. and one or more of nickel (Ni): 0.05-0.3%, molybdenum (Mo): 0.02-0.2%, and vanadium (V): 0.005-0.1%, with the balance being Fe and unavoidable impurities, wherein the Ca and S satisfy the following relational expression 1, and the steel material is characterized in that the microstructure of the surface portion is composed of ferrite or a composite structure of ferrite and pearlite, and the microstructure of the center portion is composed of acicular ferrite. [Equation 1] 0.5≦Ca / S≦5.0 (where each element represents its weight content)

This invention proposes a martensitic stainless steel with excellent stress corrosion resistance and its manufacturing method. The chemical composition of the steel, by weight percentage, includes: 0.10–0.20% C; 0.2–0.5% Si; 0.4–0.8% Mn; ≤0.030% P; ≤0.005% S; 11.5–13.0% Cr; 0.006%–0.012% Ce; 0.15%–0.35% Al; 0.08–0.15% Ta; 0.005–0.010% Zr; 0.04%–0.08% N; Ta+Zr+Al) / N: 4.0–7.5, with the balance being Fe and unavoidable impurities. The steel plate is produced through smelting, continuous casting, heating, rolling, and heat treatment. The combined effect of the elements promotes the formation of a highly dense passivation film, Ta3N5. Through optimized design of the quenching-partitioning process, the microstructure of the steel is controlled to be tempered martensite + 6-9 vol.% stable retained austenite. The steel of this invention has a yield strength ≥919 MPa, tensile strength ≥1126 MPa, elongation ≥17%, room temperature impact energy ≥94 J, and stress corrosion cracking time ≥192 h under a 650 MPa load and a ≥95℃ chloride ion concentration 10 mg / L aqueous solution environment.

Provide is an austenitic alloy material having excellent SCC resistance. An austenitic alloy material disclosed herein contains 19.0-28.0 mass% of Cr, 28.0-37.0 mass% of Ni, and 2.00-6.00 mass% of Mo, wherein: the number density ND1 of fine low-S inclusions, which have an Fn1 defined by expression (1) of 5.0 or more and an equivalent circle diameter of 2.0–10.0 µm, is 3.0 number / mm2 or more; the number density ND2 of coarse low-S inclusions, which have an Fn1 of 5.0 or more and an equivalent circle diameter of greater than 10.0 µm, is 2.0 number / mm2 or less; and the number density ND3 of high-S inclusions, which have an Fn1 of less than 5.0 and an equivalent circle diameter of 2.0 µm or more, is 2.0 number / mm2 or less.　Fn1=(Mg+Al+Ca+Ti+V+Mn) / S(1) Here, in the element symbols in expression (1), the contents of the element in the corresponding inclusions is substituted by mass%.

The invention belongs to the technical field of welding machining, and particularly relates to automatic electric arc welding equipment for dry powder extinguisher bottle body machining, the automatic electric arc welding equipment comprises a workbench, a protection assembly and a scrap collecting assembly, and a supporting seat is fixedly arranged on the workbench. A V-shaped structure formed by combining the outer expansion of the circular hole of the protection pad and the lower expansion of the inner side of the side sleeve can gather gap leakage chips, and can push V-shaped bottom chips and welding groove chips to the chip gathering assembly for directional chip removal in cooperation with the first groove and the second groove, so that the chips are prevented from splashing on the arc surface of the bottle opening from the source, the defects such as hot burns and hard spots are eliminated, and a stress concentration source is prevented from being formed; the stress corrosion cracking risk during high-pressure filling and long-term service of the bottle body is effectively reduced, the structure safety of the bottle body is guaranteed, the inclined supporting base is matched with the arc-shaped surface of the protection pad, chippings rapidly slide down along an arc-shaped track under the gravity effect, and the chipping removal efficiency is further improved.

A method and a system for evaluating stress corrosion cracking sensitivity of a welded component are provided. The method includes performing an in-situ tensile test on a welded component to be tested to obtain mechanical property parameters of each zone of the welded component to be tested; determining sizes and positions of notch specimens of the welded component to be tested by means of a finite element simulation method; processing specimens of the welded component to be tested; respectively performing a slow strain rate tensile test on the specimens of the welded component to be tested until the specimens are fractured in both an inert environment and a test environment, so as to obtain reductions of area of notch roots of the specimens of the welded component to be tested; and calculating stress corrosion cracking sensitivities of various zones of the welded component to be tested.

A new 7xxx aluminum alloy provides a unique combination of quantifiable physical characteristics. The alloy may be generally described as a corrosion resistant aluminum-zinc-magnesium-titanium-boron-cerium based alloy that is copper free or only includes slight amounts of copper as an impurity.

A topological optimization design method for a grillage spring relates to the technical field of grillage spring design, and comprises the following steps: S1, creating a geometric model of the grillage spring through parametric modeling; s2, on the basis of the geometric model, constructing a numerical simulation model to simulate the stress state of the grillwork spring under the full-life working condition, and performing stress calculation analysis to obtain the stress peak value of the spring and the stress sensitive area of the spring; s3, taking reduction of the stress peak value and the stress sensitive area of the spring as an optimization target, and carrying out structural topological optimization on the geometric model; s4, carrying out stress optimization evaluation on the novel spring structure obtained after topological optimization, and if an evaluation result does not meet requirements, returning to S1 or S2 to carry out iterative optimization until an optimization scheme meeting the requirements is obtained; the method breaks through the limitation that a traditional design method depends on empirical type selection, and the obtained spring optimized structure can effectively reduce the risk of stress corrosion cracking.

A weld joint stress corrosion testing apparatus and method. The testing apparatus comprises a fixture (100), a test piece (200), a fixed part (300) and a moving part (400); the fixture (100) comprises a first end wall (110) and a second end wall (120) which are oppositely arranged; the test piece (200) is arranged between the first end wall (110) and the second end wall (120); the test piece (200) is of an inverted arch structure, and the bottom of the inverted arch structure is a weld joint testing area; the fixed part (300) is arranged on the side of the first end wall (110) facing the second end wall (120); and the moving part (400) is arranged on the second end wall (120) and used for applying pressure to the test piece (200) so that two ends of the inverted arch structure are clamped between the fixed part (300) and the moving part (400). In the testing apparatus, a fixed-point stress corrosion test can be performed on a weld spot of the test piece (200), and targeted evaluation can be performed on the stress corrosion status of the test piece (200), so as to avoid stress corrosion cracking of a welded piece during use.

The invention belongs to the technical field of metal corrosion and protection, and relates to a nuclear power explosion valve stainless steel welded joint stress corrosion cracking evaluation method, which comprises the following steps: dissecting and sampling a welded joint simulation piece at a specified part, and carrying out simulation piece hardness measurement, metallographic analysis and SCC crack growth rate measurement to obtain a measurement result; establishing a relation curve of the crack growth rate and the hardness and a relation curve of the crack growth rate and the load; carrying out hardness detection on the welding joint area of the in-service component, and drawing a base metal-heat affected zone SCC crack growth rate cloud chart; analyzing a finite element structure of a welding joint, measuring residual stress of a welding part of a structural component, and determining a cracking sensitive position of a heat affected zone SCC; and according to the SCC cracking sensitive position of the heat affected zone and the wall thickness of the in-service part welding joint, calculating the residual life of the heat affected zone of the in-service part welding joint. The method can effectively predict the service life of the welding joint on the main pipeline.