20 August 2022, Volume 46 Issue 8
    

  • Select all
    |
    Testing & Research
  • Research Progress of Laser Additive Manufacturing Formed 316L Stainless Steel
    LI Chao
    Materials For Mechanical Engineering. 2022, 46(8): 1-7. https://doi.org/10.11973/jxgccl202208001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Laser additive manufacturing technique has the advantage of rapidly forming complex-shaped parts, and has received widespread attention in recent years. Two laser additive manufacturing techniques, directed energy deposition and selective laser melting, are introduced. The research progress of laser additive manufacturing formed 316L stainless steel is reviewed from the aspects of common defect, microstructure and texture, and mechanical properties. The current problems of laser additive manufacturing formed 316L stainless steel are analyzed, and its development prospects are prospected.
  • Thermal and Electrical Conductivity of Different Content Al2O3 Micro-Particle Modified Epoxy Composites
    YANG Jia, GAO Zhipeng, LIU Yi, LIU Qian, XIONG Zhengwei
    Materials For Mechanical Engineering. 2022, 46(8): 8-14. https://doi.org/10.11973/jxgccl202208002
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Different content (10wt%-40wt%) Al2O3 micro-particle modified epoxy composites were prepared by blended solution method. The influence of Al2O3 micro-particle content on thermal and electrical conductivity of the composites was studied. The results show that when the content of Al2O3 micro-particles were 10wt% and 20wt%, the Al2O3 micro-particles were well dispersed in the matrix. With increasing content of Al2O3 micro-particles, the micro-particles contacted with each other and agglomerated. With increasing content of Al2O3 micro-particles from 10wt% to 40wt%, the thermal conductivity of the composites increased from 0.30 W·m-1·K-1 to 1.11 W·m-1·K-1 at room temperature; the glass transition temperature increased from 115.44℃ to 122.89℃; the linear expansion coefficient decreased from 56.86×10-6 K-1 to 34.86×10-6 K-1; the resistivity decreased from 4.27×1010 Ω·cm to 3.01×1010 Ω·cm; the dielectric constant increased from 7.97 to 10.36 at 50 Hz; the dielectric loss factor at high frequency larger than 100 Hz was basically unchanged.
  • Effect of Re Content on Solidification Structure of Fourth Generation Nickel-Based Single Crystal Superalloy
    WANG Lei, LIU Yang, SONG Xiu, SUN Shixin, LIU Shizhong, LI Jiarong
    Materials For Mechanical Engineering. 2022, 46(8): 15-21,27. https://doi.org/10.11973/jxgccl202208003
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the fourth generation nickel-based single crystal superalloy DD15, single crystal superalloys were prepared by adjusting its Re content (mass fraction) to 5%, 6% and 7%, respectively. The effects of Re content on the solidification microstructure characteristic and element distribution of the alloy were studied. The results show that with increasing Re content, the precipitation temperature and dissolution temperature of γ' phase of the alloy increased, while the solidus temperature decreased slightly and the liquidus temperature had no obvious change. With increasing Re content, both the primary and secondary dendrite spacings increased, the content of (γSymbolk@@γ') eutectic microstructure increased, while the size and volume fraction of γ' phase decreased. Increase in Re content could decrease the segregation degree of negative segregation elements such as Re, W, Mo, Cr and Co in the alloy structure, but increase the segregation degree of the positive segregation element Ta.
  • Influence of Annealing Temperature on Microstructure and Mechanical Properties of Nanocrystalline Copper
    LIU Linbo, CHEN Jiawen, SHEN Xixun
    Materials For Mechanical Engineering. 2022, 46(8): 22-27. https://doi.org/10.11973/jxgccl202208004
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Bulk nanocrystalline copper with a thinkness of about 600 μm was prepared by electrodeposition, and then was annealed at 100-250℃. The effect of the annealing temperature on the microstructure and mechanical properties of the nanocrystalline copper was studied. The results show that both unannealed and annealed nanocrystalline copper showed a face-centered cubic structure. As the annealing temperature rose from 100℃ to 250℃, the diffraction peak intensity of (200) crystal faces of the nanocrystalline copper gradually increased. With the increase of annealing temperature, the tensile strength of the nanocrystalline copper gradually decreased while the elongation after fracture increased first and then decreased; and the numbers of both the surface tensile deformation zones and the large and deep dimples on the tensile fracture increased. The nanocrystalline copper had the relatively good tensile properties after annealing at 200℃, with the tensile strength up to about 500 MPa and the elongation after fracture of nearly 30.5%.
  • Mechanical Properties and Failure Assessment Curves of 9Ni Steel Welded Joint
    LIU Changjun, GONG Weizhong, ZENG Xin, XU Xiuqing, LIU Junjie, TAN Jianping
    Materials For Mechanical Engineering. 2022, 46(8): 28-32,39. https://doi.org/10.11973/jxgccl202208005
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The tensile and fracture properties at 20℃ room temperature and -158℃ low temperature of 9Ni steel welded joint, base metal and weld were obtained by experiments, and the effects of temperature on the properties were compared and analyzed. Approximate R6 option 2 failure assessment curves (FAC) for the base metal and weld, as well as FAC for the 9Ni steel welded joint were established and compared. The results show that the tensile and fracture properties of the base metal and the tensile properties of the joint and weld at low temperature were higher than those at room temperature, but the fracture toughness of the weld hardly changed with temperature. The yield strength and fracture toughness of the weld at different temperatures were lower than those of the base metal, and the weld was a weak area of the 9Ni steel welded joint. The envelope area of the approximate option 2 FAC constructed with room temperature tensile properties was slightly smaller than that with low temperature tensile properties, so the approximate option 2 FAC constructed with room temperature tensile properties can be used for safety evaluation of 9Ni steel welded joints. The FAC of 9Ni steel welded joint constructed by segment selection of the approximate option 2 FACs of the base metal and weld at room temperature can be used for safety evaluation of 9Ni steel defect-containing structures at low temperatures in the most conservative way.
  • Cause of Unknown Images in Cryogenic Nickel-based Alloy Weld Radiographic-Inspection Film of LNG Storage Tank
    CAI Xiaotao, QI Yanchang, WEI Jinshan, MA Chengyong
    Materials For Mechanical Engineering. 2022, 46(8): 33-39. https://doi.org/10.11973/jxgccl202208006
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    During the construction of large liquefied natural gas storage tanks, spot-like and floccus unknown images were found on the radiographic-inspection film of the 06Ni9DR steel weld by the ENiCrMo-6 nickel-based alloy electrode. The cause of unknown images was analyzed, and the effect of unknown images on the mechanical properties of weld was studied by microstructure observation, energy spectra analysis, hardness test, cryogenic impact tests, and thermodynamic calculations. The results show that the spot-like and floccus images were mainly caused by large-sized tungsten-rich inclusions and niobium-molybdenum-rich precipitate clusters. The average hardness of areas of inclusions and precipitate clusters were 456, 288 HV, respectively, which were both higher than that of the substrate; the tungsten-rich particles and precipitate clusters had a negative effect on the stability of tensile strength and cryogenic impact toughness of the weld joints. The quantity of unknown images decreased significantly after replacing the electrode. The unknown images were related to uneven mixing of coating components or uneven particle size of the flux during the production of nickel-based alloy electrodes, resulting in the abnormal enrichment of alloy elements in the weld metal.
  • Effect of Post Treatment Process on Microstructure and Low Cycle Fatigue Properties of Selective Laser Melting Formed Hastelloy-X Alloy
    PAN Min, ZHANG Hongqi, TAN Luyi
    Materials For Mechanical Engineering. 2022, 46(8): 40-45,52. https://doi.org/10.11973/jxgccl202208007
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Hastelloy-X alloy was fabricated by selective laser melting (SLM) process, and the effects of different post treatment processes (solution treatment of 1 175℃×2 h, hot isostatic pressing of 1 175℃/150 MPa×1 h or 1 175℃/150 MPa×2 h) on the microstructure and low cycle fatigue properties of the alloy were studied. The results show that the SLM formed alloy had a typical molten pool boundary morphology and a columnar crystal structure composed of fine dendrites, and there were metallurgical defects such as microcracks, pores and holes. Solution treatment eliminated the boundary of the alloy molten pool, and the grains transformed from columnar to equiaxed. Hot isostatic pressing could further close the cracks and pores in the alloy, and small discontinuous M6C carbides precipitated along the grain boundaries. Compared with solution treated alloy, hot isostatic pressed alloy had better low cycle fatigue properties, and the low cycle fatigue life of the alloy obtained under 2 h hot isostatic pressing time was slightly higher. Fatigue cracks propagated in a transgranular manner for solution treated alloy, while propagated in a mixed transgranular+intergranular mode for hot isostatic pressed alloy.
  • Grain Size Assessment of Thin-Walled 304L Steel Welded Tube by Ultrasonic Attenuation Method based on Continuous Wavelet Transform
    HOU Huaishu, LI Jinhao, LU Ding, XIA Shuaijun, XIN Jianlong
    Materials For Mechanical Engineering. 2022, 46(8): 46-52. https://doi.org/10.11973/jxgccl202208008
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Grain size of base metal and weld of thin-walled 304L austenitic stainless steel welded tube after solid solution treatment at different temperatures (800-1 350℃) were counted by tests. The ultrasonic signals of base metal and weld were triple wavelet decomposed by ultrasonic attenuation method based on continuous wavelet transform to extract the characteristic energy. The feasibility of ultrasonic attenuation method to evaluate grain size of welded tube was studied. The results show that with increasing solid solution temperature, the base metal grain size and the corresponding ultrasonic characteristic energy decreased; in the actual detection, the relative characteristic energy threshold of ultrasonic signals could be set between 600 and 1 000; in this case, the grain size was between 7 and 8.5, and the grain size was qualified. With increasing solid solution temperature, the grain size of weld increased, and characteristic energy first increased and then decreased and then increased, and reached the maximum at about 1 050℃; in the actual detection, the relative characteristic energy threshold of ultrasonic signals could be set between 140 and 180; in this case, the grain size was 8.5-9, and the grain size was qualified. Ultrasonic attenuation method could be used to quickly and nondestructively evaluate the grain size of thin-walled 304L austenitic stainless steel welded tube.
  • Comparison of Microstructure and Hardness of Phosphor Copper Ball Produced by Rolling and Upsetting Processes
    YANG Yong, WANG Jiaxin, WANG Bin, YAO Yulong
    Materials For Mechanical Engineering. 2022, 46(8): 53-57,67. https://doi.org/10.11973/jxgccl202208009
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The microstructure, hardness and surface temperature at the end of production of phosphorus copper ball with diameter of 25 mm by rolling and upsetting processes were comparably studied. The results show that compared with the rolling process, the surface of the phosphorus copper ball by upsetting process was smooth; the grain was obviously refined, and grain boundary was clear; the element distribution was uniform; the grains were mainly equiaxed and the number of columnar grains was relatively small. The maximum surface temperatures of the phosphorus copper ball far away from and near the outlet tank at the end of production by upsetting process were lower than those by the rolling process. The heart hardness of the phosphorus copper ball by upsetting process was obviously higher than that by the rolling process, and the surface hardness fluctuated less. Compared with the rolling process, the phosphorus copper ball by the upsetting process had the technical advantages of good quality, environmental protection and low energy consumption.
  • Effect of Tantalum Addition on High Temperature Oxidation Resistance Mechanism of Ni-5Al and Ni-10Al Alloys
    WANG Huicong, LIU Jingye, LI Weizhou, XIE Chuanbin, LI Hao, ZHANG Xiuhai
    Materials For Mechanical Engineering. 2022, 46(8): 58-67. https://doi.org/10.11973/jxgccl202208010
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Ni-based high-temperature alloys with different mass fractions (0-7%) of tantalum were prepared by powder metallurgy based on the composition of Ni-5Al and Ni-10Al alloy, and the effect of tantalum addition on the high temperature oxidation mechanisms of two alloys was investigated by 1 100℃×100 h high temperature oxidation test. The results show that oxidation mass gain per unit area of Ni-10Al alloy with the same content tantalum was higher than that of Ni-5Al alloy. The addition of tantalum promoted the growth of NiO and the formation of NiTa2O6 in the oxide film of Ni-5Al alloy; as the oxidation went on, the oxide layer composed of Al2O3 and NiAl2O4 formed at the NiO/matrix interface, which hindered the further oxidation of the alloy. The oxide film on surface of Ni-10Al alloy with tantalum consisted of a dense NiO oxide layer on the outside and a loose oxide layer on the inside composed of NiO, Al2O3, NiAl2O4 and NiTa2O6; there were fine holes in the inner oxide layer; the low high temperature oxidation resistance of the alloy was related to the loose oxide film, and formation of defects and NiTa2O6 in the oxide film.
  • Influence of Laser Energy Density on Microstructure of Selective Laser Melting Formed Al4SiC4/AlSi10Mg Composites
    SUN Jing, WU Jun, ZHU Zhongliang, YANG Shuai, LI Fuzhong, YAN Dapeng, ZHAO Weigang, WANG Lianfeng
    Materials For Mechanical Engineering. 2022, 46(8): 68-74. https://doi.org/10.11973/jxgccl202208011
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The Al4SiC4/AlSi10Mg composite was fabricated by selective laser melting process with ball-milling mixed powders of SiC and AlSi10Mg. The effect of laser energy density (76.2, 80.0, 91.5 J·mm-3) on the microstructure of the composite was explored. The results show that a sub-micro scale Al4SiC4 reinforcing phase was produced by the interaction between the laser beam and the composite powder. The phase exhibited needle-like morphology and distributed in clusters or parallel arrangement around the original SiC particles. With the increase of the laser energy density, the Marangoni convection intensified in the melt pool, promoting the generation of Al4SiC4; so the original SiC reinforcements were transformed into Al4SiC4 grandually. In addition, the morphology of the Al4SiC4 phase changed from needle-like to cluster-like or parallel-arranged sheet-like morphology.
  • Effect Mechanism of Different Dust Particles on Fatigue Crack Growth Behavior of 7N01-T6 Aluminum Alloy
    TANG Xionghui, HE Guanqiang, ZENG Xianghao, WU Shuzhou, WANG Yubin, TANG Zhenheng, CHEN Yuqiang
    Materials For Mechanical Engineering. 2022, 46(8): 75-82. https://doi.org/10.11973/jxgccl202208012
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The influence mechanism of different dust (road-dust and coal-dust) particles on the fatigue crack growth behavior of 7N01-T6 aluminum alloy was studied by fatigue crack growth test, scanning electron microscope quasi in-situ observation. The results show that during crack growth stage at stress ratio of 0.1 and stress intensity factor range less than 18 MPa·m1/2, the fatigue crack growth rate of aluminum alloy under road-dust or coal-dust particle environment was obviously smaller than that under air environment, and the crack growth rate under coal-dust particle environment was the smallest; this was because the size of coal-dust particles was obviously larger than that of road-dust particles and the crack closure effect was aggravated. With increasing stress ratio to 0.5, the difference between the fatigue crack growth rate in the dust particle environment and that in the air environment decreased, which was related to the weakening of crack closure effect with increasing stress ratio. Dust particles increased the crack closing gap, promoted the crack closing effect, and led to a large number of slip bands and microcracks at the crack tip, which greatly consumed the energy of crack growth and reduced the crack growth rate.
  • Optimization of Laser Carbon-Boron Alloying Process for 45 Steel and Microstructure and Properties of Alloying Layer Under Optimal Process
    LI Haitao, CHENG Jingtian, FAN Shuaiqi, XU Jinfu
    Materials For Mechanical Engineering. 2022, 46(8): 83-88. https://doi.org/10.11973/jxgccl202208013
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The carbon-boron binary alloying layer was prepared on the surface of 45 steel by laser alloying process. The process was optimized by orthogonal test, and the microstructure and properties of alloying layer under the optimal process were studied. The results show that the optimal process obtained by orthogonal test included laser power of 2.2 kW, scanning speed of 500 mm·min-1, overlap rate of 40%, and mass ratio of boron and carbon powder of 6.0:3.5. The alloying layer prepared under the optimal process was composed of Fe3C, Fe2B, FeB and γ- (Fe, C) phases, and consisted of alloying zone and heat affected zone. The microstructure of alloying zone was mainly columnar and cellular crystals, with a thickness of about 600 μm and an average hardness of 879 HV. The microstructure of heat affected zone was composed of acicular martensite and retained austenite, and its grains gradually became smaller from the matrix to the alloying zone. The thickness of heat affected zone was about 450 μm, and the hardness presented gradient distribution between 220-768 HV; The friction coefficient of alloying layer sample was about 0.466 6 and the wear rate was 0.455 3×10-14 m3·N-1·m-1; compared with 45 steel matrix sample, the wear resistance was greatly improved.
    • Material Properties & Application
  • Effect Mechanism of Modification Process on Electrical Conductivity of Al-0.4Mn Alloy
    GUO Jialin, LIU Jing, LUO Gan, DU Jun, ZHOU Mingjun
    Materials For Mechanical Engineering. 2022, 46(8): 89-93,99. https://doi.org/10.11973/jxgccl202208014
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Al-0.4Mn alloy was modified by B and rare earth element Y, Sm and Ce. The influence mechanism of modified elements on the electrical conductivity of the alloy was studied. The results show that Al-0.4Mn alloy could be effectively modified by right content of B or Y element when the single element was added into the alloy, and the largest electrical conductivities of alloy were 26.13, 25.32 MS·m-1, improving by 6.80% and 3.47% that of unmodified alloy, respectively. Ce and Sm elements would reduce the electrical conductivity of the alloy. The composite modification of 0.3wt% B +0.5wt% Y had a better effect on improving the electrical conductivity of the alloy; the electrical conductivity was 26.64 MS·m-1, improving by 8.9% that of unmodified alloy. When the alloy was composite modified by 0.3wt% B +0.5wt% Y, the precipitated AlB2 by borylation adsorbed Mn and Y at the same time, promoting the precipitation of doped borides and Al-Mn-Y phase; part of the Al3Y formed by Y had a certain adsorption effect on Mn, which further reduced the solid solution amount of Mn in the aluminum and lattice distortion of the substrate, and significantly improved the electrical conductivity of the alloy.
  • Effect of Quenching Cooling Rate on Microstructure and Corrosion Resistance of Zr-4 Alloy
    CHEN Lei, SU Bin, SUN Qiaoyan, ZHU Bo, BAI Xinfang
    Materials For Mechanical Engineering. 2022, 46(8): 94-99. https://doi.org/10.11973/jxgccl202208015
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Zr-4 alloy was heated to 1 000℃ for 5 min, and then was cooled to room temperature at cooling rate of 200, 20, 2, 0.2, 0.02℃·s-1. The effects of quenching cooling rates on microstructure and corrosion behavior of the alloy in 360℃/18.6 MPa water were studied. The results show that the average width of α phase plate in alloy increased from 1.4 μm to 28.0 μm, and the average particle size of the second phase particles increased from 38 nm to 580 nm with decreasing cooling rate from 200℃·s-1 to 0.02℃·s-1. The second phase particles were mainly distributed in grain boundaries of α phase plate at cooling rate of 200, 20, 2℃·s-1, and were distributed both inside the crystal and grain boundaries at cooling rate of 0.2, 0.02℃·s-1. When the cooling rate decreased from 200℃·s-1 to 0.2℃·s-1, the increase of the second phase particles helped to release the compressive stress in the oxide film and improved the corrosion resistance of the alloy. A number of microcracks initiated around the second phase particles, and the corrosion resistance decreased at the cooling rate of 0.02℃·s-1. The corrosion resistance was the best at the cooling rate of 0.2℃·s-1, and the ZrO2 grains in the oxide film were mainly columnar crystals with dense structure.
  • Effect of Process Parameters on Compactness of Ti6Al4V Alloy Formed byLaser Selective Melting
    ZHAO Jinmeng, LU Lin, WANG Jingrong, ZHANG Liang, WU Wenheng
    Materials For Mechanical Engineering. 2022, 46(8): 100-104. https://doi.org/10.11973/jxgccl202208016
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Ti6Al4V alloy was prepared by selective laser melting technique. The effects of laser power, scanning hatch and powder thickness on the compactness of the alloy were studied by orthogonal experiment method, and the formation mechanism of hole defects was discussed. The results show that the powder thickness had the greatest influence on the relative density of the formed alloy, followed by the scanning hatch, and the laser power had the least influence. The relative density of the alloy increased first and then tended to be stable with increasing laser power, decreased with increasing scanning hatch and powder thickness, and increased with increasing bulk energy density. The optimal process was laser power of 200 W, scanning hatch of 0.10 mm and powder thickness of 0.03 mm, at this time the relative density of the alloy was 99.24%. The alloy existed two kinds of hole, including pores and keyholes; the former was mainly caused by the inert gas inside the equipment and powder vapour not escaping in time due to the high temperature gradient inside the molten pool; and the latter was mainly caused by spheroidize and shrink effect of molten pool due to improper process parameters.
  • Effect of Ni-Mo Binder Content on Mechanical Properties of Spark Plasma Sintered TiC0.7N0.3-based Cermets
    HUANG Zijian, LUO Zhanpeng, ZHANG Zhan, ZHANG Yan, GUO Weiming, LIN Huatay
    Materials For Mechanical Engineering. 2022, 46(8): 105-108. https://doi.org/10.11973/jxgccl202208017
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking TiC0.7N0.3, WC, C, Ni and Mo powder as raw materials, TiC0.7N0.3-based cermets with 0, 2wt%(Ni-Mo), 10wt%(Ni-Mo) binder were prepared by spark plasma sintering technology. The effect of binder content on the microstructure and mechanical properties of the cermets was studied. The results show that the TiC0.7N0.3-based cermets displayed a typical black core-gray ring structure. With increasing content of the Ni-Mo binder, the relative density of cermets increased, the proportion of core phase TiC0.7N0.3 decreased, the proportion of ring phase (Ti,W,Mo)(C,N) increased, the TiC0.7N0.3 particle size decreased, the fracture toughness increased, and the hardness increased first and then basically unchanged. The cermet with 10wt%(Ni-Mo) binder had excellent comprehensive mechanical properties with hardness of 17.14 GPa and fracture toughness of 6.76 MPa·m1/2.
  • Effect of Pre- and Post-Weld Quenching and Tempering on Tempering Stability and Hot Melting Loss Resistance of Surfacing Layer of SDDVA Steel
    WU Shaojun, GUO Peng, LI Ling, ZUO Pengpeng, WU Xiaochun
    Materials For Mechanical Engineering. 2022, 46(8): 109-116. https://doi.org/10.11973/jxgccl202208018
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    SDDVA steel was treated by tungsten argon arc surfacing and quenching and tempering. The effect of pre- and post-weld quenching and tempering on tempering stability and hot melting loss resistance of the surfacing layer was studied. The results show that the microstructure of the surfacing layer was tempered martensite under two processes. There were more dispersed carbides precipitated from the surfacing layer under post-weld quenching and tempering process, and the microstructure was smaller; the martensite structure was more stable. The hardness reduction of the surfacing layer under post-weld quenching and tempering process after tempering at 600℃ for 48 h was only 10.2%, which was less than 30.4% of the surfacing layer under pre-weld quenching and tempering process. In the molten aluminum melting loss test at 700℃, the melting loss mass loss of the surfacing layer under pre-weld quenching and tempering process was greater than that under the post-weld quenching and tempering process, the thickness of the interface layer was larger, and the reaction between the surfacing layer and liquid aluminum was more severe. The surfacing layer under post-weld quenching and tempering process had better tempering stability and hot melting loss resistance.
  • Marine Atmospheric Corrosion Resistance of Painted Electroplated Steel Plates after Damage of Surface Coating and Plating
    GONG Lihua, PAN Feng
    Materials For Mechanical Engineering. 2022, 46(8): 117-121,126. https://doi.org/10.11973/jxgccl202208019
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The micromorphology and element distribution of corrosion product near the scratch of painted electrogalvanized steel plate and electrogalvanized nickel alloy steel plate explored in the marine atmosphere for 2 a after damage of surface coating and plating by scratch. The marine atmospheric corrosion resistance of painted electroplated steel plates after damage of surface coating and plating was discussed, and compared with original electrogalvanized steel plate and electrogalvanized nickel alloy steel plate. The results show that the marine atmospheric corrosion resistance of original electrogalvanized nickel alloy steel plate was worse than that of electrogalvanized steel plate, which was related to cracks in electrogalvanized nickel alloy steel plate during electroplating. After painting, although cracks existed in the zinc nickel alloy plating, the corrosion width near scratch was less than that of electrogalvanized steel plate, indicating that the marine atmospheric corrosion resistance of plainted electrogalvanized nickel alloy steel plate after damage by scratch was better than that of electrogalvanized steel plate, which was related to the phosphate formed by phosphating treatment before painting plugging cracks, and the existence of coating making the corrosive medium reach the coating only through the scratch side and the coating defect, and the nickel in the coating playing an advantage of improving the thermodynamic stability.
    • Failure Analysis
  • Fracture Causes of External Upset P110 Tubing
    WANG Shangwei, LUO Yougang, ZHAO Pengyu, CHEN Xiaoli, LI Dejun
    Materials For Mechanical Engineering. 2022, 46(8): 122-126. https://doi.org/10.11973/jxgccl202208020
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A external upset P110 tubing with a size of ϕ73.02 mm×5.51 mm used in a tight sandstone gas well was fractured. The fracture causes of the tubing were analyzed by means of macro/micro-morphology observation, chemical composition analysis, microstructure obsevation and mechanical property testing. The results show that the fractured tubing was located on the upper part of the tubing string, and subjected to a high axial tensile stress, and its material had a high sensitivity to sulfide stress corrosion cracking, and the H2S in produced gas of the gas well provided sulfide corrosion environment for the tubing, resulting in the sulfide stress corrosion cracking of the external upset tubing. The hardness of the tubing was high, and there was a large sulfide inclusion in the structure, which promoted the fracture of the tubing.
Quarterly Established in 1978
Sponsor:
ShangHai Ship and Shipping Research Institute Co,.Ltd.
ISSN 1674-5949
CN 31-2023/U
　 Copyright © Materials For Mechanical Engineering, All Rights Reserved.
Powered by Beijing Magtech Co. Ltd,.