最新刊期
卷 54 ， 期 5 ， 2024
- 摘要：As a typical representative of current high-efficiency and high-quality welding methods, laser welding technology has been utilized in various fields with technical advantages such as high stability and low deformation. With the continuous improvement of the rated power of the laser heat source, 10 000-watt high-power laser welding has become a popular international cutting-edge welding technology. Utilizing the ultra-high power density of 10 000-watt laser, the welded seam with greater depth-to-width ratio characteristics can be obtained. Under the same plate thickness conditions, the use of 10 000-watt laser welding can reduce the number of layers of weld passes, thus reducing the number of interlayer cleanup and reducing the number of unnecessary beveling, etc., which can greatly improve the welding efficiency. The paper summarizes and analyzes the domestic and international research status, development trend and problems of 10 000-watt laser self-melting welding, 10 000-watt vacuum laser welding, 10 000-watt laser-arc hybrid welding and 10 000-watt laser submerged arc coupling welding. It mainly involves weld shaping, molten pool behavior characteristics, physical properties of plume glow, and inhibition of welding defects.关键词：10 000-watt laser;laser welding;laser-arc hybrid welding;research status
- 71
- |
- 4
- |
- 0
发布时间：2024-06-03 - 摘要：The study involved the multi-layer and multi-pass welding of 40 mm thick S690QL high-strength steel. The research focused on observing the microstructure characteristics of the weld metal and heat affected zone, as well as counting the number and morphology of M-A constituents. Additionally, tests were conducted to evaluate the impact toughness and fracture toughness of the base metal, weld metal, and heat affected zone. The results revealed that multiple thermal cycles facilitated the precipitation and segregation of carbon elements. M-A constituents were present in both the weld metal and coarse crystal zone, with contents of 5.8% and 12.5% respectively. The average size of the M-A constituents was measured at 0.157 μm and 0.194 μm. In the coarse-grained zone, the M-A constituents exhibited a larger size and formed a chain-like distribution along the grain boundary of the prior austenite. The average CTOD values for the base metal, weld metal, and coarse crystal area were 0.38 mm, 0.25 mm, and 0.22 mm respectively. Notably, the force-displacement curve of the coarse crystal zone demonstrated a significant localized steep drop, indicating an accelerated crack growth rate due to the presence of coarse M-A constituents. Furthermore, the impact absorption energy of both the weld metal and coarse crystal zone exhibited a significant decrease with decreasing temperature, suggesting an increased embrittlement effect of the M-A constituents at lower temperatures. At -40 ℃, the impact absorption energy of the weld metal sharply decreased, close to the CGHAZ, indicating that the adverse effect of M-A constituents on toughness dominated at low temperatures.关键词：high-strength steel;M-A constituents;CGHAZ;impact toughness;fracture toughness
- 48
- |
- 9
- |
- 0
发布时间：2024-06-03 - 摘要：This study employed a mechanical mixing method to successfully incorporate Mg particles into the lead-free solder Sn58Bi, resulting in a novel composite solder Sn58Bi-xMg (x=0, 0.2, 0.4, 0.6, 0.8, 1.0). In-depth observation and investigation were conducted regarding the microstructure of the solder joints formed by these composite solders on Cu substrates and the growth of intermetallic compounds (IMCs) at the interfaces. The experimental results indicated that the introduction of Mg particles played a role in refining the microstructure of the solder joints. Simultaneously, the uniformly dispersed Mg particles in the matrix also suppressed the precipitation of Bi phases, contributing to the enhancement of solder refinement and overall strength. With the increase in Mg particle content, the thickness of IMC gradually decreased. Particularly, when the addition of Mg particles was 0.4 wt.%, the IMC thickness reached its minimum at only 3.03 μm. It is noteworthy that when the Mg particle content exceeded 0.4 wt.%, the larger-sized Mg particles were prone to aggregation and oxidation, leading to a less-than-satisfactory strengthening effect. Through observations of the growth of IMC grains, it was verified that the introduction of Mg particles successfully refined the IMC grains, achieving a fine-grain strengthening effect and improving the overall strength of the solder joints. Compared to solder joints without added Mg particles, the shear strength of Sn58Bi0.4Mg solder joints increased by 30%. Additionally, the appearance of ductile dimples on the fracture surface indicated a significant improvement in the ductility of the solder joints. These research findings provide new insights and methods for the improvement of soldering technology.关键词：Mg particles;Sn58Bi lead-free solder;microstructure;IMC
- 28
- |
- 1
- |
- 0
发布时间：2024-06-03 - 摘要：For laser welding of AH36 steel with different laser powers and welding speeds, high-speed cameras were used to extract plasma images during the welding process, meanwhile spectral information was collected. Finally, a GA-BP(Genetic Algorithm-Back propagation) neural network was established to predict the quality of the weld, namely the depth and width of fusion, and the prediction results were compared with commonly used regression analysis methods. The results showed that the depth and width of the weld seam increase with the increase of laser power, and decrease with the increase of welding speed; The plasma area, height, grayscale, and electron density all show an increasing trend with increasing laser power. When using a regression model for prediction, the relative error of melt depth prediction is 18.2%, and the relative error of melt width prediction is 12.1%. The use of an un-optimized BP neural network results in significant changes in relative error due to randomness. After optimizing using the GA algorithm and introducing process parameters as input features, the relative error of melt depth prediction is reduced to 7.23%, and the relative error of melt width prediction is reduced to 5.79%.关键词：AH36 steel;laser welding;plasma;regression analysis;neural network
- 20
- |
- 6
- |
- 0
发布时间：2024-06-03 - 摘要：ODS steel has excellent high-temperature mechanical properties, radiation resistance, and thermal creep resistance, and is one of the most potential candidate materials for the next generation nuclear reactor fuel element cladding. The welding technology of ODS steel mainly includes fusion welding, brazing, pressure welding, etc. According to the cladding structure of nuclear fuel elements, three welding methods, namely electron beam welding, rotary friction welding, and pulse current assisted diffusion welding, are selected for comparative study, and their microscopic morphology evolution is analyzed to reveal the optimal welding method and the evolution law of interface morphology. The results show that Y2O3 precipitates at the grain boundaries of the welded joints under electron beam welding and rotary friction welding processes, and pulse current assisted diffusion welding has no oxide precipitation and agglomeration. Pulse current assisted diffusion welding has prominent advantages for Fe-Cr ODS steels.关键词：oxide dispersion strengthened steel;nuclear fuel element welding;electron beam welding;rotary friction welding;pulsed current assisted diffusion welding
- 15
- |
- 2
- |
- 0
发布时间：2024-06-03 - 摘要：Cobalt-based Co-Cr-Ni-Si-W alloy powder was prepared by vacuum induction melting combined with gas atomization, with high sphericity, good dispersion, low content of impurity elements, and a melting point of about 1073.39℃~1112.58℃. The alloy powder was mixed with binder to make CoCrNiSiW paste brazing filler metal, and GH4169 high-temperature alloy was used as the brazing base material, to study the CoCrNiSiW brazing filler metal wettability on the base material, and to compare the brazing performance of different specifications of alloy powder. The results show that brazing temperature 1180 ℃, holding time 10min, CoCrNiSiW alloy brazing material can be spread on the surface of the GH4169 alloy base material, has a better wetting ability, and the use of -325 mesh specifications of the joints after the brazing of the powder organization is uniform, less porosity defects, so that the joints of the weld strength is higher, the joints of the shear strength is 127 MPa，the tensile strength is 369 MPa.关键词：Melting gas atomization;Cobalt-based brazing powders;brazing;Joint properties
- 15
- |
- 1
- |
- 0
发布时间：2024-06-03 - 摘要：The submerged arc welding test of 440 MPa HSLA steel was carried out with three welding heat inputs of 20 kJ/cm, 25 kJ/cm and 30 kJ/cm, and the effects of welding heat input on the microstructure and mechanical properties of the welded joints were studied by optical microscope, a scanning electron microscope and so on. It was shown that under three different heat inputs, the microstructure of weld metal was mainly composed of pre-eutectic ferrite, side lath ferrite, acicular ferrite and a small amount of residual austenite, and the microstructure of the coarse-crystalline heat-affected zone was mainly composed of granular bainite. With the increase of welding heat input, the content of acicular ferrite in the weld metal decreased, the first eutectic ferrite and side lath ferrite content in the gradual increase in the grain size of the coarse grain heat-affected zone in the granular bainite increased significantly, the weld metal with a diameter greater than 1 μm of inclusions in the ratio of the weld metal gradually increased from 40.7% to 59.9%, so that the strength of the weld metal and the impact toughness of the low-temperature decline; When the heat input was 20 kJ/cm, the average hardness value of the weld metal was the highest, and the low-temperature impact toughness reaches the optimum; when the heat input increased from 20 kJ/cm, the weld impact work decreased from 186 J to 130 J, the size of the ligamentous fossa in the impact fracture decreased gradually, and the depth gradually became more and more shallow, and the fracture morphology was transitioned to the quasi-dissolutional fracture by the ductile fracture, which lowered the energy required for the crack expansion, and made the impact of absorptive work decreasing.关键词：HSLA steel;submerged arc welding;heat input;acicular ferrite;impact toughness
- 17
- |
- 5
- |
- 0
发布时间：2024-06-03
Important Issuse
- 摘要：The fatigue properties of commonly used 4 mm thick 5083 aluminum alloy plate single side corner welded joints for rail transit vehicles were studied, and their S-N curves and conditional fatigue limits were obtained. Metallographic microscope and scanning electron microscope were used to observe the microstructure and fatigue fracture of the joints, and the fatigue fracture mechanism was analyzed. The results show that the microstructure of 5083 aluminum alloy fillet weld joints is uniform and there are no microcracks. The hardness at the weld center is the lowest, and it increases with the increase of the distance from the weld center, and tends to be stable after reaching the base metal; the tensile strength between the vertical plate and the bottom plate of the single side corner joint is only 110 MPa, far lower than the 324.5 MPa of the base metal; under 107 cycles of loading, the median fatigue limit is 7.33 MPa, which is only 2.25% of the base metal strength, indicating that the fatigue performance is poor when the alternating load is applied along the vertical plate direction; fatigue cracks originate from the root of the weld, and there are multiple crack sources in the fatigue fracture due to the presence of pores and other defects in the weld; In summary, when designing single-sided fillet welded joints for 5083 al-alloy, the vertical plate should not be subjected to alternating loads.关键词：5083 aluminum alloy, fillet joint;fatigue property;fatigue crack;alternating load
- 25
- |
- 3
- |
- 0
发布时间：2024-06-03 - 摘要：To address the issues of cracks and pores in aluminum alloy battery sealing nails during traditional laser welding processes and to enhance production efficiency, we employed a self-developed multi-wavelength ring fiber laser to weld 2 mm thick 3003 aluminum alloy cover plates and 0.95 mm thick sealing nails. The study investigated the impact of key process parameters such as inner and outer ring welding power and defocusing amount on the weld formation at a constant welding speed. The experimental results show that at a welding speed of 40 mm/s, with an optical fiber (inner ring) power of 500 W, a semiconductor (outer ring) power of 1 700 W, and a defocusing amount of +1.5 mm, the weld penetration reached 0.6 mm, and the weld width was 1.2 mm, resulting in the optimal welding effect. At this point, the consistency of the melt depth at various positions of the weld was high, with minimal welding spatter and no explosion points, pores, or cracks. Furthermore, actual sample welding tests demonstrated the stability and reliability of the welding process.关键词：multi-wavelength ring laser;sealing nail welding;laser welding;defocusing amount;weld depth;weld width
- 25
- |
- 2
- |
- 0
发布时间：2024-06-03 - 摘要：The crack defect of 1.5mm thick 2A12-T4 aircraft aluminum alloy skin was repaired by friction stir welding (FSW) process. The microstructure evolution, mechanical properties and material flow behavior of the joint were studied. The results show that: the joint surface was well formed after welding. The arc pattern was uniform and clear without obvious defects. Slight flash occurred at the edge of the shoulder action area. The macrostructure of the joint was observed that the obvious phenomenon that the aluminum-clad layer was stirred into the matrix. The cross section of the joint was trapezoidal and could be divided into base metal zone, heat-affected zone, heat-affected zone and stir-ring zone. Dynamic recrystallization occurred in the stirring zone. The grains in the stirring zone form uniform fine equiaxed grains with average grain size of 2.68μm. The grain size in the stirring zone was much smaller than the average size of 16.94μm of base metal zone grain. The obtained joint tensile strength was 379.88MPa, reaching 91% of the base metal tensile strength. The fracture position of the joint occurred near the thermal affected zone. The macro section was relatively flat, but there were obvious tearing edges and dimples in the micro section.关键词：2A12 aluminum alloy;FSW;microstructure;crack repair;mechanical property;material flow behavior
- 21
- |
- 1
- |
- 0
发布时间：2024-06-03 - 摘要：A needle less stir friction spot welding adhesive hybrid connection process is proposed for the connection of aluminum alloy sheets. Based on the cohesive force model, the finite element software ABAQUS was used to simulate the tensile shear fracture process of needle free friction stir welding adhesive hybrid joints, and the effects of different solder joint arrangements and adhesive types on the mechanical properties of the hybrid joints were studied. The results show that the arrangement of solder joints has no significant effect on the tensile and shear loads of the needle free friction stir welding adhesive hybrid joint, but it can affect the crack propagation behavior inside the hybrid joint; The peak tensile shear load of the flexible adhesive 2015 hybrid joint is greater than that of the brittle adhesive AV138 hybrid joint, and the failure displacement is also greater than that of the brittle adhesive AV138 hybrid joint.关键词：Friction stir welding;Bonding;Mixed connection process;Tensile and shear mechanical properties
- 14
- |
- 1
- |
- 0
发布时间：2024-06-03 - 摘要：To explore the Friction Stir Welding (FSW) process for large-width fin radiator aluminum alloy thick plates, 20.5 mm thick 6063-T5 aluminum alloy fin radiator extrusion profiles were used as test materials and welded using a static gantry-type two-dimensional production equipment. Post-welding, the joints were analyzed and tested using an optical microscope, a microhardness tester, and an electronic universal tensile testing machine for metallographic analysis, microhardness analysis, and tensile and bending mechanical property tests. The experimental results indicate that under the welding process parameters of 600 revolutions per minute (r/min) and a welding speed of 140 millimeters per minute (mm/min), the tensile strength of the joints was 158.0 MPa, which is 87.7% of the base material's strength. The hardness in the weld zone was somewhat lower compared to the base material, with two distinct hardness softening areas present in the heat-affected zones (HAZ) on both the advancing and retreating sides, with the lowest hardness value being approximately 33 HV. The joints exhibited ductile fracture in tensile testing, and no fractures occurred when the joints were bent to 180°. This demonstrates that the FSW process can achieve well-formed, macroscopic defect-free welded joints, with microstructural and mechanical property results that meet the requirements for engineering applications.关键词：6063-T5 aluminum alloy;thick plate friction stir welding;welding defect;mechanical property
- 26
- |
- 2
- |
- 0
发布时间：2024-06-03 - 摘要：Bridge U ribs are usually produced by multiple welding machines at the same time, and the melting pole gas welding machine or submerged arc welding machine can be selected, and the welding speed is generally about 0.4 m/min. This paper uses Tandem double wire welding process for testing, under the premise of ensuring welding quality, the welding speed can be increased to 1.2 m/min, which greatly improves the production efficiency. The test found that when multiple sets of double-wire welding equipment were welded to the end of the U rib at the same time, the phenomenon of arc magnetic bias blowing was very easy to occur, which affected the welding penetration and weld formation at the end of the U rib, resulting in poor welding. To solve this problem, a control method to suppress arc bias blowing was developed, which mainly increases the second pulse current in the base value stage of the pulse current to improve the anti-interference ability of the arc. The peak current, peak time and number of the second pulse affect the effect of suppressing arc bias, and the number of the second pulse is calculated according to the base value maintenance time of the first pulse and stored in the welding machine, and the peak current and peak time of the second pulse are adjusted in real time according to the change of the base value feedback voltage. At the same time, when the main machine and slave trigger the output of the second pulse in the double wire welding process, the test finds that the main machine triggers the output of the second pulse according to the parameters stored in the welding machine, and the moment when the slave triggers the second pulse is controlled by the host, and when the host is in the pulse peak decline stage, the slave outputs the second pulse, and the welding effect is the best.关键词：tandem;arcblow;U-rib;pulse;peak
- 26
- |
- 2
- |
- 0
发布时间：2024-06-03 - 摘要：Using JMP analysis software for experimental design (DOE) to study the impact of gas flow rate, fuel-to-gas ratio, cutting nozzle height, cutting speed, and cutting oxygen pressure on the quality of thick plate flame cutting, and analyzing the extent of the impact of each factor on quality response, as well as optimizing the relevant parameters accordingly. A 180 mm thick Q235B steel plate was selected for cutting experiments using C3H8 as the experimental gas. The results show that for thick plate flame cutting, the cutting oxygen pressure should not be too high, as the surface groove is sensitive to pressure; the preheating flame should be a slightly carburizing flame, with a longer flame and smaller temperature difference, which is beneficial for the protection effect of cutting oxygen and results in higher surface quality; the cutting nozzle height should not be too high; the gas flow rate should be moderate, otherwise, there will be an upper melting edge and a concave upper part, which cannot ensure a right-angle edge on the upper rim. Utilizing this experimental parameter optimization technique, quality cutting tests were conducted on 180 mm carbon steel plates using propane, natural gas, acetylene, and the newly developed "Hydro Edge" gas, all of which yielded good cutting results, verifying the universality of the optimization techniques.关键词：plate;flame cutting;influencing factors;process parameters
- 18
- |
- 6
- |
- 0
发布时间：2024-06-03 - 摘要：The CO2 gas-shielded welding was used for partial penetration corner welding of Q420qD steel with 16 mm thickness, the welding process of flat, vertical and elevation weld was optimized, and the microstructure and mechanical properties of the welded joints were analyzed. The results showed that the microstructure of the weld metal (WM) and the heat-affected zone (HAZ) was stable under different heat input conditions (13.25~19.77 kJ/cm). The microstructure of the WM was mainly pre-eutectic ferrite and acicular ferrite, the coarse grain zone has a mixed bainite, acicular ferrite and pearlite, the ferrite and pearlite in the fine grain zone were uniformly distributed. The hardness of welded joints varies as follows: HAZ > WM > base material (BM). The yield strength of welded joints (558~669 MPa) was significantly higher compared to the BM (464 MPa), and the tensile fracture location all occurred in the HAZ; The impact energy of the WM and HAZ at -20 ℃ was above 69 J, exhibiting good impact toughness.关键词：Q420qD steel;corner joint;welding process;mechanical properties
- 25
- |
- 3
- |
- 0
发布时间：2024-06-03 - 摘要：The study explored the effects of different thicknesses of copper interlayers on the microstructure and mechanical properties of laser-welded joints between 301L stainless steel and 6082-T6 aluminum alloy. The experiment utilized a 10 kW fiber laser with robotic automation for welding, and various welding powers and speeds were set. The results indicated that with the addition of a copper interlayer, good weld appearance quality could be achieved at a welding speed of 31 mm/s and laser power between 3.1~3.5 kW. As the welding heat input increased, the weld morphology shifted from V-shaped to nail-shaped, and when the copper interlayer thickness was 0.1 mm, the weld exhibited significant necking. The addition of a copper interlayer led to a reduction in hardness at the weld edge, an increase in toughness and mechanical properties, and a decrease in cracks. The tensile-shear strength first increased and then decreased with the increase of welding parameters, reaching the highest value when the copper interlayer thickness was 0.05 mm, the laser power was 3.1 kW, and the welding speed was 31 mm/s. The optimal welding parameters varied with the thickness of the copper interlayer. The copper interlayer effectively improved the quality of laser welds between stainless steel and aluminum alloy and enhanced the mechanical properties of the joints, but it was necessary to select an appropriate thickness of the copper interlayer and welding parameters.关键词：copper interlayer;dissimilar metals;laser welding;weld quality
- 18
- |
- 1
- |
- 0
发布时间：2024-06-03 - 摘要：To evaluate and compare the resistance spot welding process performance of 1.2 mm thick SCR1000 and SCR1200 cold-rolled martensitic steels, resistance spot welding experiments were conducted using the OBARA DB-220 type spot welder. The study compared the welding current window, joint failure mode, mechanical properties, microstructure, and fatigue performance of the two steel grades. The results indicate that as the steel strength increases, the overall welding current window gradually shifts to the left, with SCR1200 achieving a smaller minimum weld core diameter and a lower welding current for spatter compared to SCR1000; the shear force of the upper limit current weld point for SCR1200 is 8.9% higher than that for SCR1000. Relative to the molten core area and base metal area, the heat-affected zone of the spot-welded joints for both SCR1000 and SCR1200 exhibited a noticeable softening zone, but with SCR1200 having a slightly higher softening zone hardness. Under the same load, the fatigue life of SCR1200 is higher than that of SCR1000, and the fatigue strength of the spot-welded joints increases with the increase in steel plate strength; the weld point toughness of SCR1000 is better, with finer and more compact dimples at the fracture surface.关键词：martensitic steel;resistance spot welding;current window;mechanical properties;fatigue performance
- 15
- |
- 1
- |
- 0
发布时间：2024-06-03 - 摘要：To acquire the resistance spot welding process window for automotive hot-dip galvanized dual-phase steel, spot welding experiments were performed on 1.5 mm thick HC420/780DPD+Z using a medium-frequency inverter resistance spot welding machine. By adjusting parameters such as electrode pressure, a welding process window consisting of various welding times and currents was established. The performance of the spot-welded joints was comprehensively assessed through microhardness testing, shear and cross-tensile tests, and metallographic examination. The research indicates that under the optimal welding process window with a welding time of 410~430 ms and a welding current of 3.4~3.6 kA, defect-free welded joints without shrinkage pores or cracks can be achieved. The average shear strength of the joints is 14.88 kN, and the average cross-tensile strength is 7.1 kN. The microhardness in the nugget zone ranges from 402~455 HV, while the hardness in the heat-affected zone is 237 HV, with no signs of embrittlement observed. The electrode life exceeds 500 weld points, meeting the requirements of the GWS-5A standard. With this process, the mechanical properties of the joints are superior, and the microstructure is primarily composed of martensite, with the hardness distribution indicating the highest hardness in the nugget zone. Additionally, the failure modes of the welded joints are predominantly interfacial fractures and button-type nugget fractures, the latter of which has greater load-bearing capacity and energy absorption capability.关键词：hot dip galvanized dual phase steel;resistance spot welding;welding process window;mechanical property;fracture mode
- 17
- |
- 1
- |
- 0
发布时间：2024-06-03 - 摘要：During the narrow lap resistance seam welding process in the continuous hot-dip aluminum-zinc production line, a common problem of welding wheel ignition occurs, leading to a decline in weld quality and causing breakage, which in turn leads to production line shutdowns. Therefore, it is necessary to analyze the causes of welding wheel ignition during the resistance welding process. The main factors discussed are welding current, contact resistance between the welding wheel and the steel strip, and contact resistance between the steel strips themselves. The analysis found that the increase in contact resistance between the welding wheel and the steel strip is the main reason for the welding wheel ignition: pollutants on the surface of the welding wheel significantly increase the contact resistance, leading to excessive heat and burning through the weld; the cleanliness of the steel strip surface also significantly affects the contact resistance, leading to uneven current distribution and causing ignition. In addition, selecting the appropriate welding current according to the thickness of the steel strip is also crucial for controlling the ignition phenomenon during the welding process.关键词：hot-dip aluminum zinc production line;mash lap resistance seam welder;weld quality;welder;spark
- 14
- |
- 1
- |
- 0
发布时间：2024-06-03
Welding Technology
- 摘要：In response to the demand for non-contact (coated) surface detection of the fillet welds of the lifting lugs before and after the load test of the CNFC-3GS new fuel transport vessel, China Nuclear Power Engineering Co., Ltd. led the development of a set of highly sensitive ACFM system and process, including a written array probe and gradient algorithm software, and tested various test blocks, and the test results were compared and analyzed. The test results showed that ACFM technology can realize the rapid and effective detection of the surface defects of the hanging lug weld of the container, and can initially judged the location and size of the defects. ACFM technology could detect circular defects with a diameter of 1mm and linear defects with a length of 1 mm, and grinding could improve its detection ability. This paper can provide technical support for service safety evaluation of ferromagnetic materials and welds.关键词：ACFM;CNFC-3GS;alternating current field measurement;weld inspection
- 19
- |
- 1
- |
- 0
发布时间：2024-06-03 - 摘要：The laser welding process with a semi-penetration lap joint, due to its advantages of high efficiency and aesthetics, is currently highly valued as a manufacturing technology for the new generation of stainless steel subway body. However, the quality control of this welding process is difficult, and how to effectively ensure the fusion width between the layers is the key to developing and applying laser welding technology with a semi-penetration lap joint. To this end, research was conducted on the ultrasonic guided wave detection method for thin plate welded joints, and a system for detecting and evaluating the internal fusion width of joints was developed. By analyzing the time-frequency characteristics of ultrasonic guided wave signals, the signal characteristic values that can reflect the internal fusion state of joints were determined. Based on this, an evaluation model that can effectively distinguish different welding qualities was established, thus achieving online detection of the internal fusion width of semi-penetration laser welded lap joints for stainless steel. The research results show that using the maximum normalized amplitude of the ultrasonic guided wave time-domain signal and the peak values of the first and second peaks in the frequency domain as input information, and using the BP neural network algorithm for classification prediction can effectively identify different connection states such as incomplete fusion, insufficient fusion width, and qualified fusion width, with a prediction accuracy of 94.4%.关键词：laser welded joint;ultrasonic guided waves;non-destructive testing;quality evaluation
- 17
- |
- 2
- |
- 0
发布时间：2024-06-03 - 摘要：To explore the experimental methods for the evaluation of thermal correction processes in steel structures, in order to meet the requirements of the European steel structure specification EN1090-2 for the assessment of flame correction processes, and to fill the gap in the specific requirements for the evaluation of thermal correction processes in the current specifications. The factors affecting the performance of steel during thermal correction were analyzed, including the properties of the base metal, the heat source, the heating control, and the cooling control. Based on these influencing factors, an experimental method for the evaluation of thermal correction processes was proposed, including the heating method for the evaluation test plates, the recording of the test process, and the content of the inspection. Through the process evaluation experiments, key evaluation variables for thermal correction processes were identified, and these variables were divided into important factors and secondary factors. Tensile, impact, hardness tests, and micrographic metallographic tests were used as the content for evaluating the effects of thermal correction. The study concluded that it is recommended to formulate a thermal correction process evaluation plan according to the material, thickness, and specific conditions of the factory for steel structures, organize thermal correction process experiments and physical and chemical tests for the test plates, and compile a thermal correction process guide. In addition, train thermal correction operators with the corresponding skill level to ensure the effective implementation of thermal correction work requirements.关键词：steel structure;heat straightening;flame straightening;procedure qualification
- 14
- |
- 3
- |
- 0
发布时间：2024-06-03
Nondestructive Testing & Quality Assurance
-
Planning and Praction Research of Practical Training Course System for New Engineering Robot Welding
摘要：According to the objectives and requirements of cross-fusion technology practice teaching in the construction of new engineering, the content of cross-discipline knowledge in robot welding practice teaching is analyzed. The teaching process is planned and designed reasonably, the robot welding workstation operation is combined with the virtual simulation programming and training, and the virtual simulation software is fully used to improve the teaching efficiency. This paper analyzes the cross-disciplinary knowledge content of robot welding training equipment adaptation, links the welding torch action trajectory programming with robot kinematics, fixture action and automatic control, metal material arc welding and welding machine control and other cross technologies, and builds a new engineering cross fusion robot welding training course system. Typical training tasks for improving the ability to plan the demand of technical posts in enterprises, improving the application ability of students to solve practical problems with cross-technology, and cultivating new engineering application-oriented talents to meet industrial needs.关键词：Robot welding;crossover technology;virtual programming;typical task;application ability- 14
- |
- 1
- |
- 0
发布时间：2024-06-03
Education & Training
- Postal code：610051
- Tel：028-83289008
- Technical support is provided by Beijing Founder electronics co., LTD 蜀ICP备07004068号-2
公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0