2023 Vol. 38 No. 3
2023, 38(3): 1-11,16.
Abstract：
The mathematical model of the necking shape is built based on the analysis of the shape characteristics during the necking stage in the uniaxial tensile test. It is that the radius r of the section vertical to the central axis is the function about the distance z(z≥0) from this section to the minimal section. This function is r=rn+rc−rn1+(zz1)p1+(zz2)p2. The function of the necking sample's surface is √x2+y2= rn+rc−rn1+(zz1)p1+(zz2)p2 in the coordinate system with the origin at the center of the minimal sec[JP4]tion of the necking specimen and the central axis as the z-axis. The necking shape can be attributed with the six characteristic parameters of rc、rn、z1、z2、p1、p2 in this mathematical model. The availability of the necking shape's mathematical model is verified by the curves' fitting with the test data of the low alloy steel and the simulation data with three sets of the stress-strain relationship's parameters.
The mathematical model of the necking shape is built based on the analysis of the shape characteristics during the necking stage in the uniaxial tensile test. It is that the radius r of the section vertical to the central axis is the function about the distance z(z≥0) from this section to the minimal section. This function is r=rn+rc−rn1+(zz1)p1+(zz2)p2. The function of the necking sample's surface is √x2+y2= rn+rc−rn1+(zz1)p1+(zz2)p2 in the coordinate system with the origin at the center of the minimal sec[JP4]tion of the necking specimen and the central axis as the z-axis. The necking shape can be attributed with the six characteristic parameters of rc、rn、z1、z2、p1、p2 in this mathematical model. The availability of the necking shape's mathematical model is verified by the curves' fitting with the test data of the low alloy steel and the simulation data with three sets of the stress-strain relationship's parameters.
2023, 38(3): 12-16.
Abstract：
The high strength steel has high strength, carbon equivalent and tendency to welding cold cracking. It is significant to ensure the welding quality and improve the welding efficiency. In this study, the welding efficiencies, welding mechanical performances, welding technologies of the manual arc welding, gas shielded welding, and double side arc welding are compared and analyzed. It is found that the efficiency of gas metal arc welding is more than 2 times of that of the manual electrode arc welding and that the efficiency of double-side welding is the highest. With the increase of the welding input increases, the strength decreases and the toughness increases. To ensure the temperature between layers/passes, at the vertical positions, the length of the welding pass for manual electrode arc welding should not be greater than 1.2 m, and that for the gas metal arc welding no greater than 0.9 m. At the horizontal positions, the length of the welding pass for the manual electrode arc welding should not be greater than 1.9 m, and that for the gas metal arc welding no greater than 2.8 m.
The high strength steel has high strength, carbon equivalent and tendency to welding cold cracking. It is significant to ensure the welding quality and improve the welding efficiency. In this study, the welding efficiencies, welding mechanical performances, welding technologies of the manual arc welding, gas shielded welding, and double side arc welding are compared and analyzed. It is found that the efficiency of gas metal arc welding is more than 2 times of that of the manual electrode arc welding and that the efficiency of double-side welding is the highest. With the increase of the welding input increases, the strength decreases and the toughness increases. To ensure the temperature between layers/passes, at the vertical positions, the length of the welding pass for manual electrode arc welding should not be greater than 1.2 m, and that for the gas metal arc welding no greater than 0.9 m. At the horizontal positions, the length of the welding pass for the manual electrode arc welding should not be greater than 1.9 m, and that for the gas metal arc welding no greater than 2.8 m.
Abstract：
Great residual stress will appear in the ceramic and metal joint in the process of braze welding due to the great difference of the thermal expansion coefficient (CTE) between the two materials, therefore, the strength of the joint decreases. Introducing the interlayer is one of the most simple and efficient methods to relieve the residual stress of the joints. In this study, the characteristics of introducing interlayer assisted brazing are analyzed from two aspects. One is to improve the plastic toughness of the soldering seam; the other is to make the joint form a good gradient transition of CTE. The research status of Cu foil interlayer, 3D-SiO2-fiber interlayer, foam metal interlayer (foam Cu, foam Ni, and foam stainless steel) and porous SiC ceramic for relieving residual stress is reviewed. The effect of microstructure optimization of the braced joint on the mechanical properties of the joint is introduced. The development of interlayer assisted ceramic metal brazing is prospected and the research is hoped to provide reference for the development and technical breakthrough of the brazing between ceramic and metal.
Great residual stress will appear in the ceramic and metal joint in the process of braze welding due to the great difference of the thermal expansion coefficient (CTE) between the two materials, therefore, the strength of the joint decreases. Introducing the interlayer is one of the most simple and efficient methods to relieve the residual stress of the joints. In this study, the characteristics of introducing interlayer assisted brazing are analyzed from two aspects. One is to improve the plastic toughness of the soldering seam; the other is to make the joint form a good gradient transition of CTE. The research status of Cu foil interlayer, 3D-SiO2-fiber interlayer, foam metal interlayer (foam Cu, foam Ni, and foam stainless steel) and porous SiC ceramic for relieving residual stress is reviewed. The effect of microstructure optimization of the braced joint on the mechanical properties of the joint is introduced. The development of interlayer assisted ceramic metal brazing is prospected and the research is hoped to provide reference for the development and technical breakthrough of the brazing between ceramic and metal.
2023, 38(3): 24-30.
Abstract：
The laser welding test of 10 mm thick 316L austenitic stainless steel with nitrogen shield was carried out by high-power fiber laser in order to reduce pores. It is found that the porosity decreases significantly with nitrogen as shield gas than argon as shield gas, and that the weld section is narrower. The excellent "keyhole" welding joint is obtained. The width of the weld surface is about 2 mm; the width of the weld root about 1.5 mm. The weld face is slightly concave, and the depth-width ration is 5∶1. The results of RT and PT meet the requirements of NB/T 47013—2015 GradeⅠ. The results of mechanical and technological properties meet the requirements of NB/T 47014—2011. The impact performance test shows that the weld has excellent impact performance. The impact fracture is observed by microscopy, and the dimples are obvious, which is a typical ductile fracture. The weld zone is mainly dendritic austenite and precipitated phase, and the HAZ is mainly twinning austenite and δ-ferrite.
The laser welding test of 10 mm thick 316L austenitic stainless steel with nitrogen shield was carried out by high-power fiber laser in order to reduce pores. It is found that the porosity decreases significantly with nitrogen as shield gas than argon as shield gas, and that the weld section is narrower. The excellent "keyhole" welding joint is obtained. The width of the weld surface is about 2 mm; the width of the weld root about 1.5 mm. The weld face is slightly concave, and the depth-width ration is 5∶1. The results of RT and PT meet the requirements of NB/T 47013—2015 GradeⅠ. The results of mechanical and technological properties meet the requirements of NB/T 47014—2011. The impact performance test shows that the weld has excellent impact performance. The impact fracture is observed by microscopy, and the dimples are obvious, which is a typical ductile fracture. The weld zone is mainly dendritic austenite and precipitated phase, and the HAZ is mainly twinning austenite and δ-ferrite.
Abstract：
Based on the requirement of the corrosion evolution and life prediction of high strength low alloy steel in the polar environment, the accelerated test environment spectrum and accelerated corrosion test method of steels in Antarctic environment are investigated, which can provide techniques for the study of the corrosion behaviors and resistance of low alloy steels serving in the low temperature and freeze-thawing environments. According to the atmospheric environmental parameters of Zhongshan station in the polar region, the Antarctic environment can be divided into three stages including the moist air, freeze-thaw cycle, and low temperature freezing environments. Then, the equivalent conversion factor is calculated based on the monitor of the galvanic corrosion current using atmospheric corrosion sensor. In the end, the simulation and acceleration process of the Antarctic corrosion environment are completed through salt spray, freeze-thaw, frozen coupling accelerated corrosion test, which provides references for the preparation of the accelerated corrosion test spectrum in the low temperature environment. The results demonstrate that the corrosion behavior under the accelerated spectrum exhibits superior consistency with the outdoor exposure test.
Based on the requirement of the corrosion evolution and life prediction of high strength low alloy steel in the polar environment, the accelerated test environment spectrum and accelerated corrosion test method of steels in Antarctic environment are investigated, which can provide techniques for the study of the corrosion behaviors and resistance of low alloy steels serving in the low temperature and freeze-thawing environments. According to the atmospheric environmental parameters of Zhongshan station in the polar region, the Antarctic environment can be divided into three stages including the moist air, freeze-thaw cycle, and low temperature freezing environments. Then, the equivalent conversion factor is calculated based on the monitor of the galvanic corrosion current using atmospheric corrosion sensor. In the end, the simulation and acceleration process of the Antarctic corrosion environment are completed through salt spray, freeze-thaw, frozen coupling accelerated corrosion test, which provides references for the preparation of the accelerated corrosion test spectrum in the low temperature environment. The results demonstrate that the corrosion behavior under the accelerated spectrum exhibits superior consistency with the outdoor exposure test.
2023, 38(3): 37-42,58.
Abstract：
The WC-17Co coating sprayed on the surface of key parts of a set of large domestic equipment becomes blue and purple locally when placed in the plant for a period of time. To study the reason for that and evaluate its impact on the coating service performance, a batch of WC-17Co coating samples are prepared. An environmental test box is used to adjust humidity and temperature to simulate the field environment for accelerated oxidation tests and in-situ observation. The adhesion, wear-resistance, and corrosion resistance are tested by pull-out method, reciprocating friction method, and electrochemical measurements. It is found that the WC-17Co coating prepared with the same parameters successfully reproduced the field corrosion appearance under the simulated conditions. By comparing the properties of WC-17Co coating before and after the corrosion, it is found that the adhesion strengths of the coating before and after the corrosion are higher than 60 MPa. The wear volume of the coating before and after the corrosion changes little. The corrosion only occurs on the surface of the coating, and the interior of the coating and substrate are not damaged. It can be concluded that the surface discoloration of the coating is due to the high temperature and humidity of the local summer environment, resulting in Co oxidation of the coating surface. The adhesion and wear-resistance of the oxidized coating are not significantly reduced. Therefore, the surface oxidation of the field coating will not affect its service performance.
The WC-17Co coating sprayed on the surface of key parts of a set of large domestic equipment becomes blue and purple locally when placed in the plant for a period of time. To study the reason for that and evaluate its impact on the coating service performance, a batch of WC-17Co coating samples are prepared. An environmental test box is used to adjust humidity and temperature to simulate the field environment for accelerated oxidation tests and in-situ observation. The adhesion, wear-resistance, and corrosion resistance are tested by pull-out method, reciprocating friction method, and electrochemical measurements. It is found that the WC-17Co coating prepared with the same parameters successfully reproduced the field corrosion appearance under the simulated conditions. By comparing the properties of WC-17Co coating before and after the corrosion, it is found that the adhesion strengths of the coating before and after the corrosion are higher than 60 MPa. The wear volume of the coating before and after the corrosion changes little. The corrosion only occurs on the surface of the coating, and the interior of the coating and substrate are not damaged. It can be concluded that the surface discoloration of the coating is due to the high temperature and humidity of the local summer environment, resulting in Co oxidation of the coating surface. The adhesion and wear-resistance of the oxidized coating are not significantly reduced. Therefore, the surface oxidation of the field coating will not affect its service performance.
2023, 38(3): 43-50,58.
Abstract：
In order to study the influence of microstructure heterogeneity of titanium alloy on hydrogen diffusion and mechanical properties, a polycrystalline microstructure model is established. The random grains are generated by the Voronoi diagram subdivision principle, and the influences of the microstructural mechanical properties and hydrogen diffusion on the loading load, grain orientation, grain size and material are analyzed. The results show that the load can promote the hydrogen diffusion and has no effect on the stress concentration. The crystal orientation is the main reason for the uneven stress distribution in the microstructure, and the larger the grain size, the more serious the stress concentration. Under the same load, the stress concentration in the β-titanium alloy is more obvious than that in the α-titanium alloy, and the hydrogen is more easily enriched in the β-titanium alloy.
In order to study the influence of microstructure heterogeneity of titanium alloy on hydrogen diffusion and mechanical properties, a polycrystalline microstructure model is established. The random grains are generated by the Voronoi diagram subdivision principle, and the influences of the microstructural mechanical properties and hydrogen diffusion on the loading load, grain orientation, grain size and material are analyzed. The results show that the load can promote the hydrogen diffusion and has no effect on the stress concentration. The crystal orientation is the main reason for the uneven stress distribution in the microstructure, and the larger the grain size, the more serious the stress concentration. Under the same load, the stress concentration in the β-titanium alloy is more obvious than that in the α-titanium alloy, and the hydrogen is more easily enriched in the β-titanium alloy.
Abstract：
The basic performance requirements of the special stainless steel plates of the MARK III cargo containment system are analyzed based on the working characteristics of the system. The production process and key quality control points for the production of the special stainless steel plates are summarized to ensure their quality and performance. The performance of the special stainless steel plate is compared with that of the conventional AISI 304L stainless steel plate. The characteristics of the special stainless steel are analyzed based on the test results.
The basic performance requirements of the special stainless steel plates of the MARK III cargo containment system are analyzed based on the working characteristics of the system. The production process and key quality control points for the production of the special stainless steel plates are summarized to ensure their quality and performance. The performance of the special stainless steel plate is compared with that of the conventional AISI 304L stainless steel plate. The characteristics of the special stainless steel are analyzed based on the test results.
2023, 38(3): 59-62,68.
Abstract：
The outer circle of ZCuAl8Mn14Fe3Ni2 alloy is cracked during the forging process. The causes of the cracking are analyzed from both the material and forging process by observing the macrostructure and microstructure of the cracked position. The results show that the inappropriate forging process results in the inconsistency of the plastic deformation of the core and outer circle, and that the defects are unhealed effectively, which can cause the material to crack during the forging process. By optimizing the forging process, the ring blank of Φ920 mm×Φ440 mm×110 mm is successfully forged.
The outer circle of ZCuAl8Mn14Fe3Ni2 alloy is cracked during the forging process. The causes of the cracking are analyzed from both the material and forging process by observing the macrostructure and microstructure of the cracked position. The results show that the inappropriate forging process results in the inconsistency of the plastic deformation of the core and outer circle, and that the defects are unhealed effectively, which can cause the material to crack during the forging process. By optimizing the forging process, the ring blank of Φ920 mm×Φ440 mm×110 mm is successfully forged.
Abstract：
The development of the additive manufacturing technology in various industries tends to be mature, and the application development in the field of ships has also made extensive progress. For the application of additive manufacturing in the shipbuilding field, the technical principles, technical applications, design evaluation, approval and inspection of the powder bed fusion, directed energy deposition, and wire arc additive manufacture used in the marine field. The necessity of the standard system in ship additive manufacturing technology is verified through the analysis and research of the CCS Inspection Guidelines for Additive Manufacturing and the new standard being compiled by the International Association of Classification Societies (IACS).
The development of the additive manufacturing technology in various industries tends to be mature, and the application development in the field of ships has also made extensive progress. For the application of additive manufacturing in the shipbuilding field, the technical principles, technical applications, design evaluation, approval and inspection of the powder bed fusion, directed energy deposition, and wire arc additive manufacture used in the marine field. The necessity of the standard system in ship additive manufacturing technology is verified through the analysis and research of the CCS Inspection Guidelines for Additive Manufacturing and the new standard being compiled by the International Association of Classification Societies (IACS).
2023, 38(3): 69-72,104.
Abstract：
The effects of three heat treatment processes of the ZG14CrNi3MoV cast steel microstructure and mechanical properties were compared, which were "single-phase zone quenching+two-phase zone quenching+high temperature tempering", "single-phase zone insulation+slow cooling into two-phase zone+high temperature tempering", "two-phase zone quenching+high temperature tempering". The results show that the two-phase zone heat treatment process has a great influence on the microstructure and mechanical properties of ZG14CrNi3MoV cast steel. The heat treatment process of "single-phase zone quenching+two-phase zone quenching+high temperature tempering" is adopted. The microstructure of cast steel is ferrite and tempered sorbite, and the strength and toughness match well.
The effects of three heat treatment processes of the ZG14CrNi3MoV cast steel microstructure and mechanical properties were compared, which were "single-phase zone quenching+two-phase zone quenching+high temperature tempering", "single-phase zone insulation+slow cooling into two-phase zone+high temperature tempering", "two-phase zone quenching+high temperature tempering". The results show that the two-phase zone heat treatment process has a great influence on the microstructure and mechanical properties of ZG14CrNi3MoV cast steel. The heat treatment process of "single-phase zone quenching+two-phase zone quenching+high temperature tempering" is adopted. The microstructure of cast steel is ferrite and tempered sorbite, and the strength and toughness match well.
Abstract：
ANSYS software is used to analyze and study the parametric structure of Workbench ACP for high-pressure fully wound gas cylinders. The layer data of carbon fiber composite layer is parameterized and adjustable, and the combined analysis of the single material gas cylinder liner and carbon fiber composite layer models is realized. According to the feedback of simulation analysis results, the layering parameters are adjusted and the design of high pressure large volume fully wound cylinders is updated and optimized. The Workbench ACP parametric structure analysis research completes a large number of engineering winding tests in the way of simulation analysis, and the optimized design can effectively shortens the product design cycle and cost investment. The research provides a certain reference value for the reliability design of this type of gas cylinder.
ANSYS software is used to analyze and study the parametric structure of Workbench ACP for high-pressure fully wound gas cylinders. The layer data of carbon fiber composite layer is parameterized and adjustable, and the combined analysis of the single material gas cylinder liner and carbon fiber composite layer models is realized. According to the feedback of simulation analysis results, the layering parameters are adjusted and the design of high pressure large volume fully wound cylinders is updated and optimized. The Workbench ACP parametric structure analysis research completes a large number of engineering winding tests in the way of simulation analysis, and the optimized design can effectively shortens the product design cycle and cost investment. The research provides a certain reference value for the reliability design of this type of gas cylinder.
2023, 38(3): 77-81.
Abstract：
The mechanical properties of the silicone rubber modified by the high oil absorption resin as the blending modifier are promoted. The tensile strength and elongation at break significantly increase. It is found that the hardness of the silicone rubber can be controlled by changing the addition of the high oil absorption resin. Besides, the oil resistance and organic solvent resistance of the modified high oil absorption resin increase. Due to the high lipophilic property and oil absorption expansion of the high oil absorption resin, the problems of the sealing failure and material damage caused by aging and corrosion deterioration of silicone rubber can be solved to increase the service life of the silicone rubber materials.
The mechanical properties of the silicone rubber modified by the high oil absorption resin as the blending modifier are promoted. The tensile strength and elongation at break significantly increase. It is found that the hardness of the silicone rubber can be controlled by changing the addition of the high oil absorption resin. Besides, the oil resistance and organic solvent resistance of the modified high oil absorption resin increase. Due to the high lipophilic property and oil absorption expansion of the high oil absorption resin, the problems of the sealing failure and material damage caused by aging and corrosion deterioration of silicone rubber can be solved to increase the service life of the silicone rubber materials.
2023, 38(3): 82-87.
Abstract：
Renewable energy based on wind energy is regarded as the most promising energy source of all energy sources available today. It has become an essential part of the new power supply. Wind turbine blades are crucial and relevant to the operating efficiency and service life of turbines. However, the working conditions of wind turbines are poor, and they are usually located in high or low temperatures, acid-base corrosion, and sandstorm environments. The blade's leading edge is highly prone to erode due to its high linear velocity. Here are summarized the factors affecting the leading-edge protection of wind turbine blades, and the protection scheme of the leading edge protection, and is put forward the problems existing in the development of the protection for the leading edge of the wind turbine blade protection.
Renewable energy based on wind energy is regarded as the most promising energy source of all energy sources available today. It has become an essential part of the new power supply. Wind turbine blades are crucial and relevant to the operating efficiency and service life of turbines. However, the working conditions of wind turbines are poor, and they are usually located in high or low temperatures, acid-base corrosion, and sandstorm environments. The blade's leading edge is highly prone to erode due to its high linear velocity. Here are summarized the factors affecting the leading-edge protection of wind turbine blades, and the protection scheme of the leading edge protection, and is put forward the problems existing in the development of the protection for the leading edge of the wind turbine blade protection.
Abstract：
The current status of material selection of pressure hulls for manned submersibles with working depths of more than 6 000 m above at home and abroad is introduced. By studying the application of metal materials for manned submersibles in various ocean powers, the research and development progress of the metal materials for manned submersible pressure hulls is reviewed, and the development trend of the technology is analyzed.
The current status of material selection of pressure hulls for manned submersibles with working depths of more than 6 000 m above at home and abroad is introduced. By studying the application of metal materials for manned submersibles in various ocean powers, the research and development progress of the metal materials for manned submersible pressure hulls is reviewed, and the development trend of the technology is analyzed.
2023, 38(3): 96-104.
Abstract：
The future development trend in the energy field focuses on green and clean energy. Lithium-sulfur battery has become a new hot spot in battery research due to its advantages of high specific energy and low cost. However, there are still many problems hindering the commercialization of lithium-sulfur batteries, such as the poor conductivity of the positive material sulfur, the shuttle effect of the positive product polysulfide, and the volume expansion of the battery's internal electrodes during the process of charge and discharge. In this study, the research progress of lithium-sulfur battery cathode materials in recent years is reviewed, the application of metal-organic framework compounds, carbon materials and conductive polymers in lithium-sulfur battery cathode materials is discussed, and the development of lithium-sulfur battery cathode materials is prospected.
The future development trend in the energy field focuses on green and clean energy. Lithium-sulfur battery has become a new hot spot in battery research due to its advantages of high specific energy and low cost. However, there are still many problems hindering the commercialization of lithium-sulfur batteries, such as the poor conductivity of the positive material sulfur, the shuttle effect of the positive product polysulfide, and the volume expansion of the battery's internal electrodes during the process of charge and discharge. In this study, the research progress of lithium-sulfur battery cathode materials in recent years is reviewed, the application of metal-organic framework compounds, carbon materials and conductive polymers in lithium-sulfur battery cathode materials is discussed, and the development of lithium-sulfur battery cathode materials is prospected.
