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Fatigue properties improvement of Low-Carbon Alloy Axle Steel by induction Hardening and Shot peening:A prospective Comparison

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Acta Metallurgica Sinica(English Letters) 2022年第8期35卷 1343-1356页

作者： G.C.Chu F.z.Hu X.J.jin y.zhang Q.Wang J.p.Hou z.F.zhang Shi-Changxu innovation Center for Advanced Material Institute of Metal ResearchChinese Academy of SciencesShenyang 110016.China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Manshan iron and Steel Co. Ltd.Maanshan 243000China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Baowu Group Masteel Rail Transit Materials Technology Company Limited Maanshan 243000China

Fatigue fracture is the major threat to the railway axle, which can be avoided or delayed by surface strengthening. in this study, a low-carbon alloy axle steel with two states was treated by surface induction hardening and shot peening, respectively, to reveal the mechanism of fatigue property improvement by microstructure characterization, microhardness measurement, residual stress analysis, roughness measurement, and rotary bending fatigue tests. The results indicate that both quenching and tempering treatment can effectively improve the fatigue properties of the modified axle steel. in addition, induction hardening can create an ideal hardened layer on the sample surface by phase transformation from the microstructure of ferrite and pearlite to martensite. By comparison, shot peening can modify the microstructure in surface layer by surface severe plastic deformation introducing a large number of dislocation and even cause grain refinement. Both induction hardening and shot peening create compressive residual stress into the surface layer of axle steel sample, which can effectively reduce the stress level applied to the metal surface during the rotary bending fatigue tests. On the whole, the contribution of induction hardening to the fatigue life of axle steel sample is better than that of the shot peening, and induction hardening shows obvious advantages in improving the fatigue life of axle steel.

关键词： Surface strengthening induction hardening Shot peening Axle steel Fatigue property improvement

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THEORETiCAL pREDiCTiON OF pROEUTECTOiD FERRiTiCTRANSFORMATiON iN HypO-pROEUTECTOiD STRUCTRAL STEELS

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Acta Metallurgica Sinica(English Letters) 1998年第3期11卷 207-214页

作者： H.B.Chang z.G.Li T.y.Hsu z.y.Xu X.y.Ruan Shanghai Technical Coll of Metallurgy Shanghai China

proeutectoid ferrite with carbon content xo precipitating from austenite in a multicomponent steel at temperature T is supposed to be equivalent to proeutectoid ferrite with the same carbon content precipitating from austenite in Fe-C binary system at temperature T'.is described as the temperature difference of proeutectiod ferrite formation, and can be calculated from the Fe-X diagrams and the equilibrium temperature A3. By introducing Tf and basing on the thermodynamic model for Fe-C binary alloy, the driving force for phase transformation from austenite to proeutectoid ferrite in multicomponent steels has been successfully calculated. Through the Johnson-Mehl equation and using the data hem known TTT diagrams, the relationship between the chemical composition and the intedecial edenly packeter as well as activation energy for proeutectoid ferrite formation can be calculated. The starting curves of proeutectoid ferritic transformation calculated in this way in some hypo-proeutectoid structural steels agree well with the erperimental data.

关键词： proeutectoid ferrite formation temperature difference interfacial enerpy parameters activation energy for diffusion Johnson-Mehl equation

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Design of precision acquisition system for precision power supply of photon source

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Radiation Detection Technology and Methods 2021年第4期5卷 586-593页

作者： p.Liu F.L.Long y.z.Du institute of High Energy physics Chinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China

purpose photon source has developed to the fourth *** requirements for beam stability and power supply output current stability have been greatly *** this paper,a precision acquisition system is designed for improving the stability for power supply output *** The acquisition system consists of two parts,the analog to digital converter(ADC)system and the temperature control *** composition and software simulation analysis are given in this *** A prototype is made and *** test results showed that the acquisition system has an effective resolution of 15.5 bits,signal-to-noise ratio(SNR)of 98 dB,and integral nonlinearity(iNL)of 86 *** internal temperature stable range is±0.06℃.Conclusions The acquisition system can fully meet the requirements of the developed photon source.

关键词： photon source Beam stability High precision Digital temperature control SNR

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Effects of SiC Nanoparticle Content on the Microstructure and Tensile Mechanical properties of Ultrafine Grained AA6063-SiC_(np) Nanocomposites Fabricated by powder Metallurgy

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Journal of Materials Science & Technology 2017年第9期33卷 1023-1030页

作者： X.yao z.zhang y.F.zheng C.Kong M.z.Quadir J.M.Liang y.H.Chen p.Munroe D.L.zhang State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong University Electron Microscope Unit University of New South Wales School of Materials Science and Engineering University of New South Wales

Ultrafine grained AA6063-SiCnpnanocomposites with 1, 5 and 10 vol.% SiCnphave been fabricated by a novel powder metallurgy process. This process combines high energy ball milling of a mixture of 6063 alloy granules made from machining chips and Si C nanoparticles and thermomechanical powder consolidation by spark plasma sintering and hot extrusion. The microstructure and tensile mechanical properties of the samples were investigated in detail. increasing the Si C nanoparticle content from 1 to 10 vol.%,the yield strength and ultimate tensile strength increased from 296 and 343 Mpa to 545 and 603 Mpa respectively, and the elongation to fracture decreased from 10.0%, to 2.3%. As expected, a higher Si C nanoparticle content generates a stronger inhibiting effect to grain growth during the thermomechanical powder consolidation process. Analysis of the contributions of various strengthening mechanisms shows that a higher Si C nanoparticle content leads to a higher contribution from nanoparticle strengthening, but grain boundary strengthening still makes the largest contribution to the strength of the *** the Si C nanoparticle content increased to 10 vol.%, the failure of the nanocomposite was initiated at weakly-bonded interparticle boundaries(ipBs), indicating that with a high flow stress during tensile deformation, the failure of the material is more sensitive to the presence of weakly-bonded ipBs.

关键词： Metal matrix nanocomposite Ultrafine grained material powder metallurgy Tensile mechanical properties

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THEORETiCAL pREDiCTiON OF THE KiNETiCS CURVES OFpEARLiTiC TRANSFORMATiON iN HypO-pROEUTECTOiD STRUCTURAL STEELS

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Acta Metallurgica Sinica(English Letters) 1998年第3期11卷 215-224页

作者： z.G.Li H.B.Chang T.y.Hsu z.y.Xu X.y.Ruan Shanghai Jiaotong Univ Shanghai China

Supposing carbon contents of ferrite phases in pearlite precipitating from austenite in multicomponent steel at temperature T and in Fe-C ystem at T' are the same the pearlite formation temperature diference, can be calculated from the FeX phase diagrams and the equilibrium temperature Al. Using Tp and Fe-C binary thermodynamic model, the driving forces for phase transformation from austenite to pearlite in multicomponent steels have been successfully calculated. Through the combination of simplified zener and Hillert's model for pearlite growth with Johnson-Mehl equation, using data from known TTT diagrams, the interfacial energy parameter and activation energy for pearlite formation can be determined and expressed as functions of chemical composition in steels by regression analysis. The calculated starting curves of pearlitic transformation in some commercial steels agree well with the experimental data.

关键词： pearlite formation temperature difference interfacial energy parameter activation enerpy for pearlite transformation,Johnson-Mehl equation

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Non‐chromate conversion process for zinc coating with durable hydrophobicity and enhanced corrosion resistance

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Biosurface and Biotribology 2022年第3期8卷 266-277页

作者： J.y.Chen z.y.Hu z.X.Li X.L.Wang C.D.Gu J.p.Tu School of Materials Science and Engineering State Key Laboratory of Silicon MaterialsZhejiang UniversityHangzhouChina Key Laboratory of Advanced Materials and Applications for Batteries of zhejiang province HangzhouChina zhejiang Ecological and Environmental Monitoring Center HangzhouChina zhejiang Key Laboratory of Ecological and Environmental Monitoring Forewarning and Quality ControlHangzhouChina

A zn‐based coating with durable hydrophobicity and good corrosion resistance was formed on a mild steel substrate,which involves electroplating zn from a non‐aqueous electrolyte,followed by passivation in an oleic acid(OA)*** electrodeposited zn coatings were porous,which facilitated the formation of a chemical conversion layer of zn oleate(zO)during OA *** zn coating after passivation had a twolayer structure,which included an outer layer of zO with a thickness of~26μm and an inner layer of zn with a thickness of~6μ*** outer layer zO is a type of metal soap with a smooth surface and durable hydrophobicity,such that water droplets can easily slip off its *** testing and electrochemical measurements in 3.5 wt.%NaCl aqueous solution indicate that the zn coating after OA passivation exhibits outstanding anti‐corrosion properties compared with those exhibited by pure zn *** corrosion products and mechanism of the two‐layer coating were *** study shows that smooth metal oleate coatings can provide hydrophobicity and corrosion resistance simultaneously to mild steel substrates.

关键词： Anti‐corrosion Electrodeposition Hydrophobic coating passivation zn oleate

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Microstructural softening induced adiabatic shear banding in Ti-23Nb-0.7Ta-2zr-O gum metal

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Journal of Materials Science & Technology 2020年第19期54卷 31-39页

作者： Silu Liu y.z.Guo z.L.pan X.z.Liao E.J.Lavernia y.T.zhu Q,M,Wei yonghao zhao Nano and Heterogeneous Materials Center School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Department of Mechanical Engineering University of North Carolina at CharlotteNC 28223-0001USA School of Aerospace Mechanical and Mechatronic EngineeringThe University of SydneyNSW 2006Australia Department of Materials Science and Engineering University of Californi1IrvineCA 92697USA Department of Materials Science and Engineering North Carolina State UniversityNC 27695USA

Ti-23Nb-0.7Ta-2zr-O gum metal(GM)is an attractive candidate material for applications that require superior mechanical *** our earlier investigation of the GM[1],geometrical softening and the generation of adiabatic shear bands(ASBs)were proposed as primary reasons for the documented anisotropic impact *** the present study,electron backscattered diffraction(EBSD)analysis reveals two different deformed microstructures,i.e.,deformed ultrafine grains(UFGs)and dynamically recrystallized UFGs,formed in the ASBs of GM samples processed by extrusion equal channel angular pressing(ECAp),*** calculation of temperature rise during dynamic compression suggests that the above microstructure differences in the ASBs was originated from their different maximum ASB temperatures(608 K for extruded GM and 1159 K for ECAp-processed GM).Moreover,our calculation on the temperature at the onset of ASBs indicates that microstructural softening is the primary cause for the development of ASBs in both extruded GM(321 K)and ECAp-processed GM(331 K).

关键词： Gum metal Split hopkinson bar Adiabatic shear band Microstructures

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preparation and properties of Self-reinforced L-and D,L-lactide Copolymer Rods

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Chinese Chemical Letters 2000年第11期11卷 1023-1026页

作者： Hu y.S. zhang z.p. Song D. Wang y.M. Bai D.R. institute of polymer Chemistry State Key Lab. Funct. Polymeric M. Nankai University Tianjin 300071 China

Since highly crystalline poly (L-lactide) (pLLA) degrades rather slowly in a biological environment and the crystalline domains remaining after partial degradation of the implant material give rise to an inflammatory response of the surrounding tissue, L- and D,L-lactide copolymer [p(L-DL)LA] having a low crystallinity is preferred in surgical applications. The thermal transitions and the mechanical properties of p(L-DL)LA rods were discussed in this paper. it was found that the self-reinforced p(L-DL)LA [SR-p(L-DL)LA] was strong enough in terms of mechanical properties compared with the self-reinforced pLLA [SR-pLLA].

关键词： DL preparation and properties of Self-reinforced L-and D,L-lactide Copolymer Rods pLLA

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EFFECTS OF TREATMENT TiME ON CORROSiON OF DiFFUSiON-ALLOyED COATiNGS OF pURE MAGNESiUM

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Acta Metallurgica Sinica(English Letters) 2007年第1期20卷 72-78页

作者： y.p. Ma J. Li J. zhu L. yang y.G. Liu z.y. Li F. zhao School of Metallurgic Engineering Xi＇an University of Architecture ＆ Technology Xi＇an 710055 China

The corrosion resistance of pure magnesium with surface alloying layer obtained by a solid diffusion alloying technique has been analyzed. To establish the optimum treatment time, the experiments were performed at 480℃ for different solid diffusion time （8, 16, and 24h）. The diffusion interaction effectiveness between zn, Al mix powder and the sample surface, depending on the treatment time for diffusion at given temperatures, has an obvious influence on corrosion resistance and corrosion mechanism. Corrosion properties were studied using the constant immersion test （in 3.0% NaCl solution, temperature is （28±1）℃, and time is 96h）. Optical microscopy （OM） and EDS （energy dispersive spectrum） composition analysis were used to examine the cross-sectional microstructural characteristics of alloyed layer of treated samples. it is shown that in comparison with the untreated samples, the treated ones possess a better corrosion resistance. The Al5Mg11zn4 phase, which formed as a continuous phase due to the diffusion of Al, zn, and Mg elements and subsequent interaction on the outermost layer of diffusion alloying zones （especially the samples treated for 24h at 480℃）, was inert to the chloride solution compared with pure magnesium and acted as a corrosion barrier, and therefore the best corrosion resistance was obtained. This protective action of Al5Mg11zn4 phase was found to change with its amount, which was controlled by the diffusion time at given temperature. it was concluded that the continuous Al5Mg11zn4 phase （Wp-zone） of the reacted layer in pure magnesium was beneficial from the point of view of corrosion resistance.

关键词： pure magnesium solid diffusion treatment time microstructure corrosion

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Decolorization of Direct Black 22 by Aspergillus ficuum

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Journal of Environmental Sciences 2001年第4期13卷 472-475页

作者： Dong, X.-j. Du, z.-y. Chen, z. Dept. of Biology/Environmental Sci. Wenzhou Normal College Wenzhou 325003 China

The decolorization of Direct Black 22 by Aspergillus ficuum has been studied. it was found that Aspergillus ficuum could effectively decolorize Direct Black 22 especially when grown as pelleted mycelia. Results showed that the media containing Direct Black 22 at 50 mg/L could be decolorized by 98.05% of the initial color in 24 h. The optimum pH and temperature of decolorization are 4.0 and 33 °C respectively. Aeration was quite beneficial to decolorization. Medium composition and the concentration of Direct Black 22 could affect the rate of decolorization. The dye degraded products assayed by UV-visible spectrophotometer and macroscopic observation showed that the decolorization of Direct Black 22 by mycelial pellets includes two important processes: bioadsorption and biodegradation. The degradation experiment agree with the Michaelis-Menten kinetics equation.

关键词： Bioassay Biodegradation Color Concentration (process) Dyes pH Ultraviolet spectrophotometers

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