20 April 2021, Volume 45 Issue 4
    

  • Select all
    |
  • WANG Lijun, KONG Weitao, RUAN Shipeng, WANG Ningtao, ZHANG Peng, WANG Dongchen
    Materials For Mechanical Engineering. 2021, 45(4): 1-7. https://doi.org/10.11973/jxgccl202104001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The types and processing technology of 10.9 grade M36 wind power bolt steel serviced in alpine region are described, and the research progress on low temperature impact properties of high strength steel for wind power bolts is reviewed from the aspects of crystal structure, chemical composition, original structure before quenching and tempering, processing technology before quenching and tempering, and quenching and tempering process. The reason for the lower low temperature impact properties for 10.9 grade wind power bolts produced by cold heading process with hot-rolled wire rod is analyzed. Finally, the measurements improving low temperature impact properties of 10.9 grade wind power bolts produced by cold heading process with SCM440 steel hot rolled wire rod are put forward.
  • LI Lei, JIANG Shaoqun, WANG Gang, XU Yi, ZHOU Zehua
    Materials For Mechanical Engineering. 2021, 45(4): 8-12,18. https://doi.org/10.11973/jxgccl202104002
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The TiO2 nanotube array film was prepared on the titanium sheet surface by anodizing method, and the microstructure of the film prepared at different anodizing voltages (15-25 V) and times (0.5-2 h)was studied. Then the film was modified by stearic acid. The wetting performance of the film before and after modification was analyzed. The results show that the average diameter and tube spacing of TiO2 nanotube increased with increasing anodizing voltage, but did not changed obviously with the anodizing time. The surface structure uniformity was affected by the anodizing time, and the structure uniformity after anodizing for 2 h was realtively good. The surface of the film before modification was hydrophilic, and after modification was hydrophobic. The more hydrophilic the film before modification, the more hydrophobic after modification. The anodizing time had a greater effect on the water contact angle of the modified film. The films prepared by anodizing at different voltages for 2 h were all superhydrophobic after modification. The average water contact angle of the modified film prepared at 20 V/2 h was the highest, and the value was 159.7°.
  • ZHENG Shaoxian, XU Longqiang, DU Baofeng, LI Gang
    Materials For Mechanical Engineering. 2021, 45(4): 13-18. https://doi.org/10.11973/jxgccl202104003
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The pulsed ultra-narrow-gap welding (UNGW) was applied to 1Cr18Ni9Ti austenitic stainless steel plate with 20 mm thickness. The microstructure, mechanical properties and corrosion resistance of the pulsed UNGW joint were analyzed. The results show that the microstructures of backing weld zone in pulsed UNGW joint were austenitic equiaxed grain+lath δ-ferrite; the microstructures of filling bead and cover pass weld zone were columnar austenite+lath and cellular δ-ferrite. The microstructures of partially melted zone were austenite + vermicular δ-ferrite; the microstructures of imperfect mixing zone were austenite+δ-ferrite, and their shape was disorderly. The microstructures of heat affected zone were austenite+striped δ-ferrite. The ductility and toughness of the pulsed UNGW joint were better than those of the direct-current UNGW joint, but the strength was lower than that of the direct-current UNGW joint. The corrosion resistance of fusion zone+heat affected zone, weld zone, whole joint and base metal of the pulsed UNGW joint increased in turn in NaCl solution. The intergranular corrosion resistance of the pulsed UNGW joint in nitric acid solution was worse than that of the base metal without sensitizing and the direct-current UNGW joint, but was better than that of the sensitized base metal.
  • LAI Chunming, TAN Hailin, CHEN Jing, LI Zhaozan
    Materials For Mechanical Engineering. 2021, 45(4): 19-24,28. https://doi.org/10.11973/jxgccl202104004
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Al-4B master alloy was prepared by reaction of KBF4 with molten aluminum. The effects of Al-4B master alloy with different mass fraction (0%-2.0%) as inoculant on grain size and mechanical properties of AZ31 magnesium alloy were studied. The results show that Al-4B master alloy was composed of AlB2 and α-Al phase. The addition of Al-4B master alloy could obviously refine the grain of AZ31 magnesium alloy, improve the uniformity of grain size and reduce the porosity. The grain refinement effect was the most obvious when the mass fraction of Al-4B master alloy was 1.0%. With increasing Al-4B master alloy content, the hardness, tensile strength, yield strength and percentage elongation after fracture of AZ31 magnesium alloy increased. The yield strength and grain size were in accordance with Hall-Petch relation. The improvement of mechanical properties of AZ31 magnesium alloy was mainly related to the fine grain strengthening, dispersion strengthening caused by AlB2 phase and the decrease of porosity of casting microstructure.
  • ZHANG Sa, ZHENG Tengfei, HAN Longfei, YANG Cunxu
    Materials For Mechanical Engineering. 2021, 45(4): 25-28. https://doi.org/10.11973/jxgccl202104005
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The NaVO2F2 compound was synthesized by hydrothermal method. The crystal structure of NaVO2F2 was analyzed by X-ray diffraction. In-situ Raman spectra of NaVO2F2 during the heating from 73 K to 573 K was obtained by Raman spectroscopy. The changes of characteristic peaks with temperature was analyzed and the phase transformation behavior was obtained. The results show that the obtained NaVO2F2 crystal was monoclinic at room temperature with space group P21/c. During the heating process, the low-temperature first-order phase transformation, transformation from low-temperature phase to P21/c phase and transformation from P21/c phase to P21/m phase occurred at the temperature point of 93, 233, 453 K, respectively. The results were in good agreement with those obtained by non-in-situ testing method, indicating that the in-situ Raman spectroscopy could be used to study the phase transformation behavior of NaVO2F2.
  • WANG Long, HE Jianping, WANG Fuxin, LIU Huarong
    Materials For Mechanical Engineering. 2021, 45(4): 29-34. https://doi.org/10.11973/jxgccl202104006
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The stainless steel wire mesh was conected by micro-plasma arc butt welding under 6 kinds of joint assembly methods composed of 3 kinds of rough selvedges, and the characteristics, influencing factors of welding spot morphology and the forming mechanism of the welding spots were studied. The results show that torispherical, ellipsoid and spindle welding spot were formed during butt welding the wire mesh. The assembly methods, insert distance of rough selvedges, position of welding torch, welding heat input and distance between torch and weft on both sides of joint (the short distance X4 and the long distance X5) had great impact on the welding spot morphology. Torispherical welding spot was devided into a type welding spot that the weft closest to the joint did not melt and b type welding spot that the weft closest to the joint melted. When X5 was constant, the radius of a type welding spot increased with X4. When X4 was constant, the radius of b type welding spot increased with X5. When the welding heat input was constant, the long axis length of ellipsoid welding spot increased with X4, and finally tended to a fixed value, and when X5 was constant, the short axis length increased firstly and then decreased with increasing X4. When the insert distance of rough selvedges was constant, the spindle welding spot volume increased with X5. The spindle welding spot volume decreased with increasing insert distance of rough selvedges when X5 was less than 0.33 mm, and increased with the insert distance when X5 was greater than 0.70 mm.
  • HUANG Yiping, LI Shaolin, LIU Hailang, JIANG Jianbo, PENG Zhiguo, TAN Yi
    Materials For Mechanical Engineering. 2021, 45(4): 35-39,45. https://doi.org/10.11973/jxgccl202104007
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The electron beam welding of 15Mn alloy steel plate was carried out after the applied magnetic field was set in weld depth direction, perpendicular to welding direction and along welding direction, respectively. The effect of the applied magnetic field on the electron beam weld formation, microstructure and properties was studied. The results show that the electron beam weld quality was good under different applied magnetic field condition, and no crack, porosity and slag welding defects existed. When the magnetic field direction was perpendicular to welding direction or along welding direction, the weld was deflected in both surface and depth direction. Under the condition of magnetic field direction along the weld depth direction, the depth and width of the weld increased, compared with those without applied magnetic field. Under the condition of magnetic field direction along the welding direction, the depth of the weld unchanged, the width increased, and the deflection angle in depth direction was relatively small. Under the condition of magnetic field direction perpendicular to the welding direction, the depth of the weld decreased, the width increased, and the deflection angle in depth direction was relatively large. The weld microstructure and distribution of section microhardness was not affected by the direction of the applied magnetic field.
  • YU Haiyan, WU Hangyu, SHI Huiru
    Materials For Mechanical Engineering. 2021, 45(4): 40-45. https://doi.org/10.11973/jxgccl202104008
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Accelerated water bath moisture absorption tests at 25 ℃ and 50 ℃ were carried out on carbon fiber reinforced polymers (CFRP) laminates, and the uniaxial tension and three-point bending tests were performed. The rule of the moisture absorption, tensile strength and bending strength varying with the moisture absorption time and the bath temperature was studied. The failure mechanism of the CFRP laminates was discussed. A residual strength model of CFRP laminates was established by fitting the experimental data. On the basis of the environmental equivalent coefficient, the hygrothermal aging life of the laminates was predicted. The results show that the average saturation moisture absorption rate of CFRP laminates at 50 ℃ was 0.77%, and was larger than 0.33% at 25 ℃. At the same moisture absorption time, the moisture absorption rate at 50 ℃ was higher than that at 25 ℃. The tensile strength and bending strength decreased by 7.4% and 17.2% after moisture absorption saturation at 50 ℃ compared with that before moisture absorption, respectively, and the decrease degree was higher than those after moisture absorption saturation at 25 ℃. The higher the bath temperature, the more serious the interface damage between CFRP laminate carbon fiber and resin, and the more obvious the cracks. The real aging life prediction method on the basis of residual strength and environmental equivalent coefficient could provide evidence for the service reliability evaluation of CFRP laminates in hygrothermal environment.
  • GAO Li, TAO Zihao, FENG Ying, WANG Shu
    Materials For Mechanical Engineering. 2021, 45(4): 46-50,56. https://doi.org/10.11973/jxgccl202104009
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Mn1-xFexCoGe1.02(x=0,0.01,0.03,0.06,0.09) alloy was prepared by arc smelting method using Fe to replace part of Mn in MnCoGe1.02 alloy, and the phase composition, crystal structure, martensitic transformation and magnetothermal effect of the alloy were studied.The results show that after replacing part of Mn with Fe, the lattice parameters and cell volume of the alloy basically showed a decreasing trend with increasing iron content. MnCoGe1.02 alloy at room temperature showed a coexisted structure with orthogonal martensite phase and hexagonal austenite phase. The alloys with x=0.01 and x=0.03 were both single orthogonal martensite phase structure. The alloys with x=0.06 and x=0.09 were both single hexagonal austenitic phase structure. The temperature of martensitic transformation increased first and then decreased with increasing Fe content, and the alloy with x=0.03 had the highest transformation temperature. The addition of Fe effectively improved the intensity difference of magnetization of the alloy. The alloy with x=0.03 had the largest intensity difference of magnetization, and at 5 T and 315 K, the alloy had the largest magnetic entropy change of 18.7 J·K-1·kg-1, indicating that the alloy had the relatively large magneto-thermal effect.
  • XU Xin, PAN Yingjun, KE Deqing, PAN Yinghui, GAN Zhanghua
    Materials For Mechanical Engineering. 2021, 45(4): 51-56. https://doi.org/10.11973/jxgccl202104010
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The boride coating was prepared on the surface of 316 stainless steel substrate by plasma cladding technique with self-made Mo-Fe-B-Cr flux-cored wire as raw materials. The microstructure, hardness, wear resistance and corrosion resistance of the coating were studied. The results show that a good metallurgical bond was formed between boride coating and substrate. There was a gradient layer with thickness of about 100 μm in the coating, and element diffusion occurred in the gradient layer. The massive hard phases of Mo2FeB2 and (Mo,Fe,Cr)3B2 in the coating was wrapped by the γ-Fe bonding phase, while there were a lot of reticulated eutectic structures of (Fe,Cr)2B and (Fe,Cr)23(C,B)6 among the bonding phase with dendritic distribution. The maximum microhardness of the coating was 757 HV,which was about 3.4 times higher than that of the substrate. The wear mass loss of the coating was less than that of the substrate, and the coating had excellent wear resistance. The wear mechanism was micro-cutting of binding phase resulting in brittle spalling of hard phase particles and the formation of abrasive wear. The free corrosion potential of the coating in 5wt% NaCl solution was slightly higher than that of the substrate, and the free corrosion current density was less than that of the substrate, indicating that the coating had good corrosion resistance.
  • SUN Xiaoran, SONG Yue, GU Xiurui, BAI Lijuan, ZHAO Xiujuan
    Materials For Mechanical Engineering. 2021, 45(4): 57-60. https://doi.org/10.11973/jxgccl202104011
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Low cycle cyclic strain fatigue test was carried out on 2.0 mm thick SPHC hot-rolled steel sheet for automobile, and the stress-strain curve, strain-life curve, strain hysteresis loop curve and related fatigue constant indicators were obtained. The fatigue fracture morphology was observed. The results show that the SPHC steel had a non-Masing effect within the test range. The fitted cyclic strength coefficient of SPHC steel was 284, and cyclic strain-hardening exponent was 0.128. The fatigue strength coefficient was 467 MPa, the fatigue strength index was -0.078, the fatigue ductility coefficient was 0.323, and the fatigue ductility index was -0.609 fitted by Manson-Coffin equation. The fatigue fracture included crack source area, crack propagation area, and transient fracture area. The crack propagation area was composed of a large number of fatigue striation, and the transient fracture area consisted of a large number of dimples. SPHC steel had good ductility.
  • LI Shibing, ZHU Yanli, XU Xiaolong, YAO Jun
    Materials For Mechanical Engineering. 2021, 45(4): 61-64. https://doi.org/10.11973/jxgccl202104012
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking the imported continuous casting and rolling rod raw materials for production of ER5356 aluminum alloy welding wire as the research object, the high temperature strength and plastic change of the continuous casting and rolling rod at different temperatures (250-550 ℃) were studied by high temperature tensile tests, and the fracture morphology was observed. The best thermoplastic temperature range was obtained. The results show that with increasing temperature, the high temperature strength of the continuous casting and rolling rod showed a single exponential decrease trend, the percentage elongation after fracture increased, and the percentage reduction of area changed little, indicating the continuous casting and rolling rod had good high temperature plasticity. With increasing temperature, the grain boundary weakened, and the area of the intergranular fracture area increased; the tensile fracture morphology changed from dimples to dimples and brittle intergranular fracture mixed morphology, and finally completely changed to the brittle intergranular fracture morphology. The best thermoplastic temperature range of ER5356 aluminum alloy continuous casting and rolling rod was 375-525 ℃.
  • MA Yinghan, ZHANG Zhen, GUO Mengyu, ZHAO Wei, ZHANG Caiyi, HU Zhengfei, GAO Shan
    Materials For Mechanical Engineering. 2021, 45(4): 65-71,80. https://doi.org/10.11973/jxgccl202104013
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The fatigue crack growth rate of F690 super-high strength steel in simulated seawater was measured by direct-current voltage drop method, and the effects of stress ratio (0.1,0.2,0.3) and loading frequency (0.15,0.30,0.60 Hz) on the fatigue crack growth behavior were studied. The corrosion fatigue process was simulated by the extended finite element method based on Paris law of energy release rate, and compared with test results. The results show that the corrosion fatigue crack growth rate of F690 steel in simulated seawater decreased with increasing stress ratio or frequency. The corrosion fatigue fracture mode was transgranular fracture, and with increasing frequency, the width of secondary cracks decreased. The simulated corrosion fatigue crack growth length of F690 steel was consistent with the test results, and the relative error was less than 0.6%, indicating that the corrosion fatigue crack growth behavior of F690 steel could be effectively simulated and predicted by the extended finite element method.
  • FANG Yanling, XIE Cheng, WU Shengchuan, ZHANG Jie, YANG Guang, QI Shiwen, LI Fei
    Materials For Mechanical Engineering. 2021, 45(4): 72-80. https://doi.org/10.11973/jxgccl202104014
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The charcteristic parameters of defects in electron beam fusion additive manufactured Ti-6Al-4V alloy were obtained by high-resolution synchrotron radiation 3D X-ray tomography technique. Combining with high cycle fatigue tests, the influence of defects on fatigue properties of the alloy was analyzed. The Z-parameter fatigue life model was modified by considering defect characteristic parameters, and an X-parameter fatigue life model was proposed. The results show that there were porosity and incomplete fusion defects in the manufactured Ti-6Al-4V alloy. The fatigue life of the alloy had significant dispersion in different stress levels and the fatigue limit with 50% survival rate was 679 MPa. Most of the fatigue cracks originated at the porosity and incomplete fusion defects. The linear fitting correlation coefficient of X-parameter-fatigue life curve by X-parameter fatigue life model was 0.878 5, and was improved by nearly 20% compared with the Z-parameter fatigue life model, the dispersion of fatigue life significantly decreased, and the prediction accuracy of the model was significantly improved.
  • LIAN Xiaojie
    Materials For Mechanical Engineering. 2021, 45(4): 81-87. https://doi.org/10.11973/jxgccl202104015
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The stainless steel containing boron was prepared by vacuum induction melting technique with adding 1.96wt% boron into 304 stainless steel. The hot deformation behavior of the steel was investigated by single pass hot compression tests at 900-1 150 ℃ and strain rate of 0.1-10 s-1. The hot deformation constitutive model of the steel was established by Arrhenius equation with five degree polynomial fitting combined with test data. The critical condition of dynamic recrystallization of the steel was determined by analysis of the work-hardening rate-true stress curves. The results show that the flow stress-strain curves of stainless steel containing boron presented a typical dynamic recrystallization type, and the dominated softening mechanism was dynamic recrystallization after hot compression under the test parameters. With increasing deformation temperature or decreasing strain rate, the peak stress and its corresponding true strain of the test steel decreased. The true stress-true strain curves calculated by the established hot deformation constitutive equation had a good agreement with the test results, and the average absolute relative error was 2.76%, indicating that the constitutive model could precisely predict the hot deformation behavior of stainless steel containing boron. The dynamic recrystallization of the steel occurred easily when the deformation temperature was relatively high and strain rate was relatively small.
  • XIA Haoyang, WU Hao
    Materials For Mechanical Engineering. 2021, 45(4): 88-93. https://doi.org/10.11973/jxgccl202104016
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A new driving force model without material fitting parameters was proposed to predict crack growth rate and overload fatigue life by introducing an equivalent residual stress intensity factor ΔKres. The crack growth length was measured by direct current potential drop (DCPD) method combined with finite element calibration, and compared with measured values to verify the accuracy of the method. On the basis of DCPD method and finite element calibration, the crack growth rate and overload fatigue life of four steels after overload were obtained by overload fatigue test to verify the accuracy of the prediction model. The results show that the overload-induced retardation appeared in four test steels after single-peak overload. The higher the overload ratio, the smaller the minimum crack propagation rate of the test steel after overload, and the lower the yield strength, the greater the retardation effect of the test steel. The relative error between crack growth length measured by DCPD method and finite element calibration and measured values was smaller than 3.75%, indicating the method had high accuracy. The trend of crack growth rate prdicted by driving force model agreed with test values by DCPD method combined with finite element calibration well, and the predicted overload fatigue life was within 2 times the error band of the test value, which verified the accuracy of driving force model.
  • ZHU Qi, LI Qiang, XIONG Zhilin, ZHANG Qichuang
    Materials For Mechanical Engineering. 2021, 45(4): 94-98. https://doi.org/10.11973/jxgccl202104017
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The cracking causes of Q960 high strength steel plate for construction machinery during cold bending process were analyzed by macromorphology observation, chemical composition analysis, microstructure observation, fracture morphology analysis, micro-hardness test, and instrumented impact test. The results show that the cracking property at the cold bending location of Q960 high strength steel plate was microcrack initiation and propagation induced by tensile stresses. During the cold bending process, the bending circular surface of the steel plate was subjected to tensile stresses, so cracks were initiated at the large TiN inclusions in the original slab. The cracks propagated along the transverse and longitudinal directions, leading to cracking of the steel plate. To avoid the recurrence of similar failure, the titanium mass fraction should be reduced from 0.18% to 0.15%, and the nitrogen mass fraction should be controlled within the range of no more than 0.003% to reduce the amount of large TiN inclusion precipitate.
  • LIU Huan, TONG Wenwei, ZHANG Shuang, ZHANG Kaikuo, LI Yanming
    Materials For Mechanical Engineering. 2021, 45(4): 99-102. https://doi.org/10.11973/jxgccl202104018
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Cracks were produced prematurely in the transition area of the shoulder root of TC4 alloy fan rotor blade of an aero-engine. The cause of the cracks was studied through macromorphology observation, fracture analysis and contact discharge test. The results show that the cracks of the failed fan rotor blades were fatigue cracks, and initiated on the surface of the transition area from the root of the leaf pot side shoulder to the exhaust edge. The induction coil closed or contacted the blade substrate and contact discharge occurred, resulting in local melting and burning of the blade substrate and melting of the flow blocking agent during the brazing process of the wear-resistant layer of the blade shoulder, which was the cause of fatigue crack initiation of the blade. It was suggested that insulating the induction coil by insulating tape and using an appropriate induction current and welding distance to prevent contact discharge between the coil and the blade.