2023 Vol. 38, No. 6

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Review
Progress Research on Evolution and Failure Behavior of Surface Coating of B30 Copper-nickel Alloy Pipe
LIU Peng, CHEN Yuyu
2023, 38(6): 1-8.
[Abstract](118) [PDF 6067KB](41)
Abstract:
The B30 copper-nickel alloy pipe is widely used in the marine heat exchange equipment and seawater pipe system due to its good seawater corrosion resistance, but the corrosion and leakage of the pipe caused by film failure occurs frequently during its service under complex working conditions. In this study, the corrosion resistance mechanism and evolution process of the B30 copper-nickel alloy pipeis surface coating are analyzed, the failure mode and influencing factors of the alloy's surface coating are expounded, and a comprehensive treatment suggestion for failure control and maintenance of the B30 copper-nickel alloy pipe are proposed.
Corrosion and Protection
Research on Preparation of Stellite Alloy Coating and Its Compatibility with Liquid Lead-Bismuth Eutectic Alloy
ZHANG Tianyi, LÜ Shasha, RUAN Zhangshun, FU Xiaogang, LONG Bin, TAO Liu, QIN Bo, LI Zhengcao
2023, 38(6): 9-14.
[Abstract](62) [PDF 6122KB](19)
Abstract:
The lead-bismuth fast reactor uses liquid lead-bismuth alloy as the coolant, which has high safety and promising development prospects as Generation Ⅳ. In this study, we mainly focus on the lead-bismuth corrosion resistant coatings. The Stellite alloy coatings are prepared on the austenitic stainless steel substrates, whose composition and microstructure are analyzed. The lead-bismuth corrosion resistance experiment of the coating is carried out to analyze its structural integrity, mechanical properties, surface oxide layer, and phase composition changes. The lead-bismuth corrosion resistance of the Stellite alloy coating is evaluated by characterizing the microstructure and mechanical properties to provide theoretical and technical support for the engineering application of the lead-bismuth fast reactors.
Effect of S2-on Corrosion Resistance of Cu-7Ni-3Al Alloy in NaCl Solutions
ZHANG Siyao, ZHANG Zhuodong, CHANG Yanli
2023, 38(6): 15-21.
[Abstract](61) [PDF 6443KB](14)
Abstract:
Cu-7Ni-3Al copper alloy is prepared by vacuum smelting based on the copper-nickel corrosion-resistant copper alloys. The corrosion rate and corrosion pattern of Cu-7Ni-3Al alloy in 3.5% (w) NaCl solutions with different concentrations of S2- are analyzed by the static total impregnation corrosion experiment. The results show that Cu-7Ni-3Al alloy with good comprehensive performance is prepared by vacuum smelting. The existence of S2- promotes the corrosion of Cu-7Ni-3Al alloy. The corrosion rate of Cu-7Ni-3Al alloy increases with the increase of S2-concentration, because in the environment of S2-, Cu-7Ni-3Al alloys will form Cu2S, and Cu2S will make the passivated film brittle and prevent the formation of oxide film, thus accelerating corrosion. Therefore, the corrosion resistance of Cu-7Ni-3Al alloy decreases with the increase of S2-content in 3.5% NaCl solution.
Life Prediction of Aluminum Alloy Beam Coatings for Rolling Stock in Laboratory Salt Spray Environment Based on Grey System Theory
ZHANG Xiaocheng, CHEN Yufan, WEI Mumeng, YAO Jinghua, WANG Hao, FAN Guodong, YANG Bojun, WANG Huaqing
2023, 38(6): 22-31,51.
[Abstract](41) [PDF 6468KB](19)
Abstract:
The life prediction model of the aluminum alloy beam coating system for multiple units under laboratory salt spray environment is established, and the service life of the coating system under this environment is predicted. First of all, based on the experimental results under the laboratory salt spray environment, the water absorption dynamics model, wet adhesion GM (1,1) model and coating thickness mathematical model of the coating system are constructed, respectively. Then, the weights of the three failure factors in the coating failure process are calculated and corrected by using the grey correlation analysis method, and the mathematical model of the coating system failure is established based on these three factors. Through the mathematical statistical verification and comparison of the test results, the model has good reliability and can accurately predict the life of the aluminum alloy beam coating of multiple units under the laboratory salt spray environment.
Cyclic Aging Study of Several Typical Heavy-Duty Coating Systems
WU Le, ZENG Dengfeng, TAO Naiwang
2023, 38(6): 32-40,51.
[Abstract](45) [PDF 11130KB](20)
Abstract:
According to the requirements of relevant corrosion protection standards, cyclic aging tests are carried out on three typical anti-corrosion coating systems including hot-sprayed galvanized composite coating, zinc-rich primer coating and non-zinc-rich primer coating, which are applied into the marine atmospheric environment. The causes for the failures are analyzed, and the anti-corrosion performances, construction costs, maintenance and environmental protection of the coatings are compared. In the cyclic aging test of the extreme corrosive environment, the main failure modes of the coatings are the crevice corrosion and physical effects caused by temperature change. The hot-sprayed galvanized composite coating and zinc-rich primer coating are recommended for the extreme corrosive environment. The development direction of the marine heavy-duty anticorrosion coating has environmental protection, low VOC and long lasting effect.
Test and Analysis
Determination of Material Properties of Al 2024-T3 Aluminum Alloy Using Nano-indentation Experiment and Interval Optimization
ZHANG Guitao, HUANG Xiang, HOU Bingyu, WANG Mingzhi
2023, 38(6): 41-51.
[Abstract](49) [PDF 12676KB](13)
Abstract:
Nanoindentation experiment has been widely concerned in the field of material mechanics testing due to its advantages of simple sample preparation and wide range of use. A plastic parameter identification method of the Al 2024-T3 aluminum alloy material considering the uncertainty of nanoindentation experiment is established. First of all, the nanoindentation experiment is carried out on the Al 2024-T3 alloy, and the load-displacement curve is obtained. Due to the inhomogeneity of the material, the experimental curve is uncertain. Based on the artificial neural network of superparametric optimization, the relationship between the material performance parameters and indentation response loading curve is established. Based on the interval optimization theory, the uncertainty of the indentation test curve is introduced. Taking the loading curvature of the indentation test curve as the uncertainty quantity, the interval optimization model of the material parameter identification based on the double-layer nested genetic algorithm is proposed, and the inverse problem of the parameter identification is solved. The advantage of this method is that it can take into account the uncertainty of experimental measurement, and the recognition result is more reliable. The validity of the established method has been verified in the identification of the Al 2024-T3 alloy plastic parameters. The identification errors of the yield stress and hardening index are-0.87% and 2.76%, respectively. This recognition method is expected to be used in the detection of mechanical properties of small size specimens.
Study on Kinetics of Multilayer TiAl3 Compound Prepared by Accumulative Roll-bonding
QIU Xingyu, FANG Hongmei, CAO Lili, YANG Dengke, YE Yuesong
2023, 38(6): 52-57,62.
[Abstract](53) [PDF 5403KB](12)
Abstract:
The solid phase reaction of the Ti/Al multilayers prepared by accumulative roll-bonding is studied by differential scanning calorimetry, X-ray diffractometer and scanning electron microscope. The kinetic characteristics of the TiAl3 phase formation in the Ti/Al multilayers prepared by accumulative roll bonding are revealed. The DSC curve obtained by testing the rolled sample according to the differential scanning calorimetry method contains two exothermic peaks, and the shape is very similar to the DSC curve obtained by the magnetron sputtering of Ti/Al films. The two exothermic peaks represent the nucleation of TiAl3 phase and the thickening of the TiAl3 phase layer in the ARB Ti/Al multilayers, respectively. In order to better understand the nucleation of the TiAl3 phase, the isothermal DSC test is carried out on the Ti/Al multilayer samples prepared by ARB. The JMA model is comparison and analysis, and a modified model based on the kinetics of phase formation in the deposition film reaction is established, which makes the DSC curve calculated more consistent with the actual measured DSC curve. The results show that in the Ti/Al multilayer samples prepared by ARB, the kinetic characteristics of the nucleation, lateral growth and subsequent thickening of the TiAl3 phase can be explained by the modified kinetics model of the phase formation in the process of sputtering deposition of films.
Process Research
Study on Purification Process of Sintered Tantalum Rod
LI Zhongxiang, ZHANG Jiankang, XIE Yongxu, CHEN Xueqing
2023, 38(6): 58-62.
[Abstract](32) [PDF 4844KB](3)
Abstract:
The purification process of the sintered tantalum rod is studied, and the results show that sheath for the molding of tantalum rod contributes to the surface contamination, which leads to the increase of C content. The latex sheath with low cracking temperature can effectively reduce the residual C compared with the rubber sheath. High temperature sintering can remove part of the residual impurities, but to completely remove them is very difficult. The HNO3 + HF acid system can effectively remove the inclusion in the surface of the tantalum rod and achieve the purification of the tantalum rod.
Study on Connection Process between Heat Pipe and Tube Sheet of Titanium Heat Pipe Heat Exchanger
YIN Yayun, LI Peng, QIU Shengwen, GAO Qi, GUO Lidong, DONG Chuangchuang
2023, 38(6): 63-66.
[Abstract](48) [PDF 4625KB](14)
Abstract:
Aimed at the problem of heat pipe and tube sheet joining of the titanium heat pipe heat exchanger with large internal and external pressure difference, a transition sleeve is put between the heat pipe and tube sheet, and the specific process specification is formulated. Firstly, we adopt the pulse TIG welding to weld the heat pipe and sleeve, then manufacture single heat pipe, and finally use electron beam welding to weld the circumferential butt joint between the sleeve and tube sheet. The sample for the test is prepared according to the optimized process. The appearance, non-destructive, low magnification metallography, pull-off and hydrostatic test are carried out on the welded joint. Results show that all the testing results can meet relevant standards, which provides key technologies for the construction of heat exchanger of high quality titanium heat pipe.
Organization and Performance
Study on Preparation of Flexible Weaveable Ti Wire/TiO2 Nanoporous Film Photoanodes and Their Photocatalytic Performance
LI Mengqi, LI Xiaolong, GU Xiaodong, SHEN Chensi, ZHANG Lisha
2023, 38(6): 67-73.
[Abstract](33) [PDF 10255KB](3)
Abstract:
Various pollutants can be efficiently degraded by semiconductor photoelectrocatalysis technology and the key of this technology is to develop efficient, easily recyclable and stable photoelectrodes. In this study, TiO2 nanoporous films grow in situ on the surface of the flexible titanium wire by using anodic oxidation technology, and the as-prepared films possess pore size diameters of 85 nm and thickness of 10 μm. The Ti wire/TiO2 nanofilm composite has excellent flexibility, and is woven into fabric photoanodes with the weight of 0.25 g and area of 36 cm2. The photocatalytic experiment is carried out on the fabric photoanodes. The results show that the photocurrent rises from 0 mA to 0.32 mA when the bias voltage increases from 0 V to 0.6 V under the illumination condition. It is worth noting that the fabric photoanodes can degrade 87.8% Rhodamine B (RhB) in the photo electrocatalytic process for 120 min under the bias voltage of 0.6 V, which significantly exceeds 60.0% and 3.6% of those of the photocatalysis and electrocatalysis. Furthermore, the degradation efficiency of RhB remains 85.0% after four cycles, showing good performance stability of Ti wire/TiO2 nanoporous film photoanodes. Therefore, Ti wire/TiO2 nanoporous film photoanode shows excellent prospects for photoelectroca-talytic degradation of contaminants.
Influence of Interlayer Materials on Microstructure and Properties of Ti/Steel Clad Plate
GUO Songtao, LÜ Lin, NIE Yuanchao, JIN Yunxue
2023, 38(6): 74-79.
[Abstract](41) [PDF 15471KB](8)
Abstract:
The effects of adding DT4 or SL3 sandwich materials on the microstructure and properties of the TA2/Q235B composite plate are studied based on the actual production line. The mechanical properties and microstructure of the TA2/Q235B clad plate are analyzed through metallography (OM), scanning electron microscope (SEM), energy disperse spectrum (EDS), X-ray diffraction (XRD) and mechanical tests. According to the study, the clad plates containing DT4 interlayer has clean interface, less compound, and uniform TiC, and its shear strength is up to 187.4 MPa. As for the clad plate with SL3 interlayer, there is more slag inclusion in the interface, where TiFe, TiNi and other compounds can be found, and the shear strength is only 148.6 MPa. The shear fracture locations of the composite plates of the two sandwiches occur on the titanium side, and the brittle fracture features are found in the fracture. The results show that the shear strength of the DT4 sandwich clad plate is higher, which is conducive to the industrial production.
Effect of Forging Temperature on Microstructure and Mechanical Properties of Nb521 Alloy Bar
HAO Xiaolei, HU Shujuan, ZHENG Genggeng, WANG Fei
2023, 38(6): 80-85.
[Abstract](64) [PDF 6340KB](11)
Abstract:
Nb521 alloy bars are forged in the temperature range of 1 000-1 400℃. The effects of forging temperature on microstructure and properties are studied by microhardness tester, metallographic microscope, tensile tester and ultrasonic flaw detector. The results show that the higher the forging temperature is, the higher the dynamic recrystallization ratio of the bar is, and the lower the annealing temperature for the subsequent recrystallization. When the forging temperature rises to 1 400℃, the microstructure of the annealed bar is fine and uniform, and the strength and plasticity match the best. Besides, it is confirmed by the ultrasonic flaw detection that increasing the forging temperature is beneficial to the homogenization of the microstructure and can significantly reduce the clutter level.
Effects of Heat Input on Microstructure and Property of MAG Welded Joints of 10CrNi3MoV Steel
CAO Wenan, YE Fan, SUN Lei, LIU Jian, NIU Jicheng
2023, 38(6): 86-91,110.
[Abstract](59) [PDF 9941KB](16)
Abstract:
10CrNi3MoV steel is welded by metal active gas welding (MAG) with different heat input. The effect of heat input on microstructure and mechanical property of the welded joints are investigated by means of microstructure analysis, fracture observation and mechanical tests. Results show that the microstructure of the welded metal is mainly acicular ferrite, with a certain amount of proeutectoid ferrite and granular bainite, when the heat input (E=11.0 kJ·cm-1, and E=14.4 kJ·cm-1) is low. When the heat input (E=18.1 kJ·cm-1) is high, the amount of acicular ferrite decreases, and the amount of proeutectoid ferrite and granular bainite significantly increase, and the microstructure coarsens. With the increase of heat input, the grain size of the coarse grained heat affected zone (CGHAZ) increases, and the microstructure transforms from lath martensite to lath bainite. The lath boundaries become blurred and the granular bainte emerges. The strength of the welded metal decreases, and the impact toughness increases slightly at first and then decreases significantly. The fracture mode changes from microporous polycondensation ductile fracture to quasi cleavage/ductile mixed fracture. When the heat input is 14.4 kJ·cm-1, the microstructure is mainly fine acicular ferrite and the welded joint has the best combination of strength and toughness.
Nonmetallic Material
Simulation and Experimental Study on Injection Molding Vulcanization of Porous Rubber Products
XU Lujie, CHEN Yuhu, ZHANG Ling, HUANG Ming, ZHAI Menglei, CHEN Wenguang
2023, 38(6): 92-99,110.
[Abstract](45) [PDF 9490KB](5)
Abstract:
Based on the experimental testing and fitting parameters of the injection molding model of the nitrile rubber material, and combining the change of the rubber rulcanization and temperature in the filling stage, the vulcanization process of thick-walled porous rubber is simulated. The influence of different filling conditions on the simulation of pressure holding vulcanization stage, and the the accuracy of the simulation is verified through relevant experiments.
Strength and Failure
Analysis on Fracture during Uniaxial Tensile Test with Round Bar Sample based on I1 Fracture Criterion
XUE Gang
2023, 38(6): 100-110.
[Abstract](35) [PDF 16320KB](11)
Abstract:
Fractures during the uniaxial tensile test with round bar of two material models are analyzed by the elastic-plastic finite element method based on I1 fracture criterion. The results indicate that the crack forms in the center of the minimal section at first. The crack unstably propagates into a circular crack the moment it forms, and then the propagation ceases. With the displacement load continuously increasing, the crack propagates step by step. The axial force reduces sharply when the crack forms and propagates unstably. The fracture strength Ib can be measured by using this characteristic of the axial force's change.

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