2021 Vol. 36, No. 6

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Materials Research
Correlation Analysis on Crack Arrest Temperature of Low Alloy High Strength Hull Steels
GONG Xuhui, XUE Gang, GAO Zhenpeng, MA Qian, FU Anxin
2021, 36(6): 1-6,35.
[Abstract](288) [PDF 1853KB](49)
Abstract:
Isothermal and temperature-gradient double tension tests have been conducted on 4 lots of low alloy high strength hull steels to study the correlation between crack arrest temperatures obtained in different temperature fields. Test results indicate that under the same main tensile stress, the value of temperature-gradient crack arrest temperature is higher than that of isothermal crack arrest temperature. The difference of these two temperatures increases linearly with the increase of main tensile stress and shows an approximately quadratic function relationship with the plate thickness. Test procedures of isothermal and temperature-gradient double tension tests have been analyzed from the perspective of energy balance and the main influencing factors including main tensile stress, nil-ductility transition temperature and plate thickness, on which basis, a correlation expression is proposed and its validity is identified by test data of low alloy high strength hull steels with thickness no more than 80 mm.
Effects of Fe Content on the Microstructures and Properties of Ti80 Alloy
TAO Huan, SONG Dejun, YANG Shengli, LI Chong, YU Yan, PAN Yifan
2021, 36(6): 7-11.
[Abstract](155) [PDF 8340KB](16)
Abstract:
The influences of Fe content (between 0.04% and 0.41%, w) on microstructures and properties of Ti80 titanium alloy have been studied. The results show that the increase of Fe content can improve the tensile strength at room temperature of Ti80 titanium alloy. The Fe content increases by 0.2%, the tensile strength increases by about 20 MPa. The increase of Fe content has no significant effect on plasticity and impact properties of the alloys. The Fe element can affect the structural morphology of the alloy. When the Fe content increases to 0.41%, the shape of α phase changes from globularity into long strip. During the 30-day test, the addition of Fe element reduces the open circuit potential of Ti80 alloy and results in the increase of average corrosion rates of the alloy under the conditions of natural seawater immersion and the seawater with a flow rate of 5 m/s. The seawater corrosion resistance of the alloy decreases, but still in the same order of magnitude with that of the normal Ti80 alloy.
Effect of SiO2Particle Size on Properties of Ni-Co-SiO2 Electrodeposited Composite Coatings
BAI Shuangfeng, LIU Xuehui, XU Likun, XUAN Junji, SHAO Yang, XIN Yonglei, LI Xiangbo, FAN Lin
2021, 36(6): 12-20.
[Abstract](142) [PDF 5691KB](14)
Abstract:
The corrosion of steel fasteners exposed to marine environment for a long time seriously affects the service safety of marine engineering equipment and facilities. Electroplated alloy coating is a common protection method for fasteners, among which nickel-cobalt alloy coating has better corrosion resistance. In the study, SiO2 particles with different particle sizes are added into Ni-Co plating solution, and by the method of electrodeposition, Ni-Co-SiO2 composite is coated on 45 steel. Influences of SiO2 particle size on surface morphology and microstructure of the composite coating are analyzed, and corrosion resistance of the composite coating in NaCl solution with mass fraction of 3.5% evaluated. Microhardness and friction coefficient of the composite coating are tested. The results show that with the increase of SiO2 particle size in the bath, the distribution uniformity of SiO2 on the surface of the composite coating increases first and then decreases. When the SiO2 particle size is 70 nm, a more complete SiO2 film is formed on the surface of the coating. Potentiodynamic polarization and electrochemical impedance spectroscopy tests show that the composite coating doped with 70 nm SiO2 has the best corrosion resistance. With the increase of SiO2 particle size in the bath, the hardness of composite coating decreases gradually, but its effect on friction coefficient is slight.
Study on Preparation of High Strength Polysulfide Sealing Putty and its Bonding Property
LI Jingrui, LIN Chong, WANG Bing, WANG Wenfei, CHENG Wei, ZHANG Jinwei
2021, 36(6): 21-25.
[Abstract](224) [PDF 4545KB](11)
Abstract:
Using liquid polysulfide rubber as main material and manganese dioxide as curing agent, the effects of ratios of different grades of polysulfide rubbers and manganese dioxide dosage on mechanical properties of sealing putty are studied, so is the effect of treatment form of rubber bonding surface on bonding properties of sealing putty. When the amount of manganese dioxide is 12 parts, the polysulfide sealing putty has better mechanical properties. The bonding strength of putty could be greatly improved when rubber bonding surface is ground with sand belt and treated with plasma.
Material Application
Numerical Simulation and Process Optimization on Hot Forming for CuNi90/10 Sock Welding Tee
YANG Qingyun, YUAN Wei, MA Junpu, ZHANG Zhiyuan
2021, 36(6): 26-30,35.
[Abstract](88) [PDF 2540KB](12)
Abstract:
Aiming at the prominent problem of low material utilization and low production efficiency in the forming process of CuNi90/10 sock welding tee, a new hot forming technology is presented, and a thermal mechanical FEM model is established based on the software Deform-3D, the effects of punch shape, feeding speed, initial temperature of workpiece and friction coefficient on horizontal load is comparatively analyzed. Results show that the quality of cylindrical convex surface of punch is the best, the optimal feeding speed is 40 mm/s, and the suitable initial temperature is 950℃~1 000℃. Besides, the smaller the friction coefficient is, the better the forming quality.
Study on Surface Treatment Process and Protective Coating System Design of Low-magnetic Stainless Steel
XU Qiang, QI Haixia, CHEN Kaifeng, ZHANG Lili
2021, 36(6): 31-35.
[Abstract](54) [PDF 1894KB](12)
Abstract:
The effects of different surface treatments on corrosion resistance and coating adhesion of low magnetic stainless steel substrate were studied. The protective coating system of low magnetic stainless steel substrate was determined by electrochemical impedance and cathodic stripping resistance test. The results showed that sand blasting with brown corundum as abrasive could not only improve the surface roughness of the substrate, met the requirements of high adhesion coating, but also reduced the electrochemical corrosion of the substrate caused by residual particles on the substrate surface. The protective coating system with epoxy zinc yellow as the bottom layer could form a dense oxide film on the surface of stainless steel, which could greatly prevent the erosion under the film and increased the corrosion resistance of the coating several times.
Preparation and Performance Research on Antifouling Coating with Large-size Bionic Microstructure
WANG Meng, XIE Zhipeng, TANG Lirong, DENG Bingfeng, ZHANG Chuyi, WANG Jingjing
2021, 36(6): 36-43.
[Abstract](203) [PDF 9086KB](27)
Abstract:
Special surface structures of marine organisms such like sharks and dolphins have antifouling function, and the peristome of nepenthes possesses the feature of one-way transmission of liquid film. Both of the structures can provide references for antifouling and drag reduction designs for ship coatings. According to the rib-like structure on the surface of shark skin, unidirectional grooves and arc-shaped structures in the peristome of nepenthes, simplified microstructure with unidirectional V-type grooves are designed, and together with drag reduction rate calculated by CFD, bionic microstructure and size of the antifouling coating is determined. The microstructure topography template is prepared by using picosecond laser to etch the surface of the aluminum alloy, and then imprint the surface of the incompletely cured antifouling coating. Through the investigation and optimization of soft/hard template, curing time and imprint pressure, coating with large-size bionic microstructure is prepared. The 3-dimensional shape tester and contact angle tester are used to characterize the surface of the bionic microstructure coating, and the real sea immersion test is conducted. The results show that the surface microstructure morphology of the bionic coating is uniform and show good antifouling performance, with the microgroove spacing of 90.8 μm, the microgroove depth of 60.3 μm, and the surface contact angle of the microstructure coating of 121.7°.
Optimization Design of Impact Load Testing Tool for Nylon Locking Sleeve
DUAN Yongqi, ZHAO Zhenping, WANG Yanfei, XU Chen, QIN Junfei
2021, 36(6): 44-48.
[Abstract](120) [PDF 6532KB](8)
Abstract:
As one part of double-layer non-linear vibration damping fastener, nylon locking sleeve can realize the pre-assembly of the fasteners by locking the upper and lower iron plates and the middle damping pad into one body, thereby greatly reducing the workload of on-site construction. According to the technical requirements, impact test should be carried out on the nylon locking sleeve after being manufactured. No damage should be left in the sleeve when it bears 6 shocks of 50 kg hammer falling freely form a height of 45 mm. In this paper, impact test tooling based on the technical requirements of nylon locking sleeve is designed, and the impulse response of the tooling computed by ANSYS. The structure is further optimized according to the calculation results, and the optimized structure can meet the strength requirements. The weight falls from 15.87 kg to 8.17 kg, which is convenient for the disassembly and assembly operations. The optimized impact tooling can meet the requirements of impact test.
Welding Technology
Design of Database Application System for Hull Structural Steel and Welding Materials
HE Lei, HE Liang, MA Xiaoyang
2021, 36(6): 49-55.
[Abstract](121) [PDF 3952KB](14)
Abstract:
In order to promote the storage validity and utilization efficiency, the database application system of hull structural steel and welding materials is designed and developed by using SQL Server as background database, VB as system development and ODBC data source as connection technology. The system has four functional modules:structural steel information query, welding material information query, standard query and report query. Structural steel welding rod has been taken as an example to test the practicability of the system. The mechanical performance prediction is realized by the construction of the intelligent framework for performance prediction and the neural network model, and the transformation of neural network matrix model into VB code. It has a certain reference and practical value for the design of structural steel and welding materials.
Effect of Heat Treatment Temperature on Microstructure and Properties of T2+Q345R Composite Plate by Explosive Welding
JIANG Xiaobo, HOU Fachen, ZHAI Weiguo, DENG Guangping, ZHAO Liang
2021, 36(6): 56-59,76.
[Abstract](114) [PDF 2234KB](12)
Abstract:
The heat treatment experiments have been carried out on T2 and Q345R explosive welding composite plate at series temperatures, and the changes of its structure and properties are observed. The results show that the heat treatment temperature has no obvious effect on the shear strength, tensile strength and elongation of T2-Q345 clad plate. When the temperature is below 600℃, the clad grain size grows slowly, and the thickness of heterogeneous full-phase microstructure at the interface has little change compared with that of the explosive state. When it is above 600℃, with the increase of temperature, the grain size of clad layer grows rapidly, and the thickness of dissimilar metallographic structure at the interface increases rapidly.
Microstructure and Mechanical Properties of Laser Welded Joint of TA5 Titanium Alloy
MU Zhuangzhuang, LIAO Zhiqian, YU Wei, LEI Xiaowei, XU Yali, MA Zhaowei, XU Lefeng
2021, 36(6): 60-66.
[Abstract](210) [PDF 7960KB](16)
Abstract:
The 8 mm thick TA5 titanium alloy is welded by IPG fiber laser, and the microstructure and mechanical properties of the welded joint analyzed. The result shows that the surface of the laser welded joint is continuous, uniform and with no splash, and there are no such internal defects as pores and cracks. The microstructure of base metal is equiaxed α phase, fine and uniform. The microstructure of weld zone is mainly composed of coarse β columnar grains, a large amount of acicular martensite α' and a small amount of lath martensite. The structure of heat affected zone is mainly composed of equiaxed α phase, a small amount of acicular martensite α' and a small amount of residue β. At the boundary of the fusion line, columnar grains and equiaxed grains are crossly crystallized and epitaxially grown, so as to ensure the stable connection of the welded joint. The Vickers hardness of each area of the welded joint varies greatly, the highest hardness exists near the fusion line, and the hardness of weld zone and heat affected zone is significantly higher than that of base metal. The tensile fracture exists at the base metal, away from the weld, indicating the tensile strength of the laser welded joint is equal to or slightly higher than that of the base metal. The high tensile strength of the weld is due to the net-basket structure formed by a large amount of acicular martensite.
Effect of Sodium Silicate on Performance of Alkaline Low Hydrogen Electrode
WANG Xiaolian, KANG Tianyou, WANG Dun
2021, 36(6): 67-70.
[Abstract](225) [PDF 2594KB](12)
Abstract:
Effect of sodium silicate on performances of alkaline low hydrogen electrode is studied. Test results show that increasing the content of sodium silicate in coating of electrode could reduce electrode sleeve length, slag viscosity and tendency of vertical welding nibs, and increase splash slightly, and that the chemical composition and mechanical properties of deposited metal of welding electrodes and content of diffusion hydrogen have no obvious change. Therefore, the welding technicality could be optimized by adjusting content of sodium silicate in the coating of alkaline low hydrogen electrode.
Performance Requirements and Analysis of Marine Aluminum-steel Explosive Composite Transition Joint
HUANG Jian, LIU Jintao, YAN Shengnan, ZHAO Liang
2021, 36(6): 71-76.
[Abstract](243) [PDF 1686KB](30)
Abstract:
Here are introduced and analyzed the material and specifications, manufacturing processes, standards and specifications, performance requirements and welding requirements of aluminum-steel composite transition joint, which will references for inspection, acceptance and standard revision of the transition joint.
Review
Reviews on Marine Aluminum Alloys for LCS of USA
GUO Zeliang, FAN Xiaojie
2021, 36(6): 77-82.
[Abstract](416) [PDF 2376KB](28)
Abstract:
Here is briefly introduced the project of littoral combat ships (LCS) of the US navy reviewed the selection of hull and superstructure materials, especially for the independence class of LCS and all-aluminum warships, and introduced the alloy system, the dimension, the type, the quantity and the specifications of the selected aluminum alloys. Further, the coating systems and the ICCP system to protect LCS from corrosion are reviewed. Finally, the recent activities of research and development of aluminum alloys in the USA are introduced.
Research Progress in Application of Graphene Oxide Based Nanohybrid in Anti-corrosive Coatings
MU Songwei, LIANG Yu, ZHANG Xinyue, CHEN Kaifeng, WANG Jingjing
2021, 36(6): 83-90,102.
[Abstract](131) [PDF 5695KB](15)
Abstract:
Graphene oxide (GO) has the features of high specific surface area and good barrier, which can be used as filler to enhance the corrosion resistance of coatings. However, the interaction between the graphene oxide sheets makes it easy to form aggregates, which hinders the full play of its barrier properties. Serious aggregation may even lead to poor mechanical properties of the coating. In addition to GO, other nanomaterials are also widely used in anticorrosive coatings and show complementary functions with GO. The results show that the nanohybrid compounds obtained by surface modification of GO and other nanomaterials could help anticorrosive coatings achieve better anticorrosive performances. Based on the study, the research progress of GO based nano-hybrid system in improving anticorrosion performance of coatings is summarized, and its future development trend prospected.
Experience Exchange
Application and Research Progress of Waterborne Anticorrosion Coatings
WANG Yingmao, ZHANG Yahao, HUANG Congshu, WANG Jingjing, LIANG Yu
2021, 36(6): 91-96.
[Abstract](381) [PDF 3091KB](75)
Abstract:
Waterborne anticorrosive coatings are one of the developing directions of anticorrosive coatings in the future. In this paper, the research status and application of four waterborne anticorrosive coatings including acrylic system, epoxy system, inorganic zinc silicate system and polyurethane system are introduced. Besides, three types of graphene-modified waterborne anticorrosive coatings are emphatically introduced according to the structural properties and application advantages in coatings of graphene. Finally, the problems of waterborne anticorrosive coatings are analyzed, and the future development trend and prospect forecasted.
Review and Prospect of High Temperature Titanium Alloy Welding
YAN Feihao, WANG Gang, FAN Jinwei, CUI Yongjie, GAO Fuyang
2021, 36(6): 97-102.
[Abstract](167) [PDF 7028KB](18)
Abstract:
Here is reviewed the development of high temperature titanium alloy welding at home and abroad. The welding characteristics of high temperature titanium alloy and the requirements for the consistency, uniformity and stability of the thermal strength, thermal stability and creep fatigue resistance of the welded joints of high temperature titanium alloy are summarized. The research status of technologies of flash butt welding, linear friction welding, electron beam welding and laser welding are introduced, and the future research direction of high temperature titanium alloy welding prospected.

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