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Fabrication of wear-resistant layers with lamellar eutectic structure by laser surface alloying using the in situ reaction between Cr and B_4C

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International Journal of Minerals,Metallurgy and materials 2016年第11期23卷 1294-1301页

作者： You-zheng Sun Jin-bao Li Daniel Wellburn Chang-sheng Liu key laboratory for anisotropy and texture of materials (Ministry of Education) Northeastern University

To improve the wear resistance of Cr5 steel, wear-resistant layers with lamellar eutectic microstructure were fabricated by laser surface alloying（LSA）, which is dependent on the in situ reaction between Cr and B_4C. Our results indicated that the hypoeutectic structures of the LSA layers were divided into interdendritic eutectic structures and dendrites. The area fraction of the eutectic structures increased with increasing laser scanning speed, which improved the hardness and wear resistance of the LSA layers. The average hardness of the LSA layer prepared at a scanning speed of 8 mm/s was HV_（0.2） 883.9, which was 1.8 times greater than that of the traditional quenched layer（approximately HV 480）. After sliding for 659.4 m, the specimen prepared at a scanning speed of 8 mm/s exhibited a volume loss of 0.0323 mm^3, which was only 29.5% of the volume loss of the traditional quenched specimen.

关键词： eutectic wear resistance laser alloying hardness

Effects of H content on the tensile properties and fracture behavior of SA508-Ⅲsteel

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International Journal of Minerals,Metallurgy and materials 2015年第8期22卷 820-828页

作者： Jia-hua Liu Lei Wang Yang Liu Xiu Song Jiong Luo Dan Yuan key laboratory for anisotropy and texture of materials (Ministry of Education) Northeastern University

SA508-Ⅲ steel was charged with different hydrogen(H) contents using a high-pressure thermal charging method to study the effects of H content on the tensile properties and evaluate the H embrittlement behavior of the steel. The results indicate that the ultimate tensile strength remains nearly unchanged with the addition of H. In contrast, the yielding strength slightly increases, and the elongation significantly decreases with increasing H content, especially at concentrations exceeding 5.6 × 10-6. On the basis of fractographic analysis, it is clear that the addition of H changes the fracture mode from microvoid coalescence to a mixture of river patterns and dimples. Carbides are strong traps for H; thus, the H atoms easily migrate in the form of Cottrell atmosphere toward the carbides following moving dislocations during tensile deformation. In addition, stress-induced H atoms accumulate at the interface between carbides and the matrix after necking under three-dimensional stress, which weakens the interfacial bonding force. Consequently, when the local H concentration reaches a critical value, microcracks occur at the interface, resulting in fracture.

关键词： stainless steel tensile properties fracture hydrog

Effects of Post-Weld Heat Treatment on Microstructure and Mechanical Properties of Al-12.7Si-0.7Mg Alloy Welded Joints by GMAW

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Acta Metallurgica Sinica(English Letters) 2014年第2期27卷 245-252页

作者： Dong Wang Changshu He Hao Wang Xiang Zhao Liang Zuo key laboratory of anisotropy and texture of materials of Ministry of Education Northeastern University

In this study, 3-mm-thick hot-extruded plates of A1-12.7Si-0.7Mg alloy were used to fabricate the joints welded by gas metal arc welding. Effects of the post-weld heat treatment include solid solution treatment, water quenching, and artificial aging treatment on the microstructure, and mechanical properties of the weld joints have been investigated. Results showed that the welded joints after solid solution and artificial aging exhibited the increases in yield strength of 166 MPa and ultimate tensile strength of 148 MPa, respectively. Based on the microstructural observations, the associated mechanisms were discussed.

关键词： Al-Si alloy Welded joint Post-weld heat treatment (PWHT) Microstructure Mechanical property

Microstructure and tensile properties of as-extruded Mg-Sn-Y alloys

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Transactions of Nonferrous Metals Society of China 2010年第B07期20卷 493-497页

作者：赵宏达秦高梧任玉平裴文利陈冬郭运 key laboratory for anisotropy and texture of materials Ministry of EducationNortheastern University

The microstructure and tensile properties of the Mg-1.0%Sn-xY(x=1.5%,3.0%,3.5%,atom fraction)alloys extruded indirectly at 350℃ were investigated by means of optical microscopy,scanning electron microscopy and tensile *** mean grain sizes ofα-Mg matrix in the three extruded alloys are 6,8 and 12μm,respectively,slightly increasing with the addition of Y. The relationship between microstructure and strength was discussed in *** results show that the addition of Y has little effect on the grain refinement of the as-extruded Mg-Sn based alloys *** only MgSnY phase is detected in the Mg-Sn-1.5%Y alloy, and the Sn3Y5 phase in the Mg-Sn-3.5%Y alloy,whereas both of them simultaneously exist in the Mg-Sn-3.0%Y *** particle shape of MgSnY and Sn3Y5 phase,inherited from the solidification,has little change before and after hot ***-Sn-3.0%Y alloy has the highest ultimate tensile strength(UTS),305 MPa,by over 50%compared with that of the other two alloys.

关键词： Mg-Sn-Y alloy extrusion microstructure tensile property

Microstructures and tensile properties of as-extruded Mg-Sn binary alloys

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Transactions of Nonferrous Metals Society of China 2010年第7期20卷 1321-1325页

作者：陈冬任玉平郭运裴文利赵宏达秦高梧 key laboratory for anisotropy and texture of materials of Ministry of Education Northeastern University(Shenyang)

The microstructure and mechanical properties of Mg-xSn （x-3, 7 and 14, mass fraction, %） alloys extruded indirectly at 300 ℃ were investigated by means of optical microscopy, scanning electron microscopy and tensile test. The grain size of the a-Mg matrix decreases from 220, 160 and 93 μm after the homogenization treatment to 28, 3 and 16 μm in the three alloys after extrusion, respectively. The results show that the grain refinement is most remarkable in the as-extruded Mg-7Sn alloy. At the same time, the amount of the Mg2Sn particles remarkably increases in the Mg-7Sn alloy with very uniform distribution in the a-Mg matrix. In contrast, the Mg2Sn phase inherited from the solidification with a large size is mainly distributed along grain boundary in the Mg-14Sn alloy. The tensile tests at room temperature show that the ultimate tensile strength of the as-extruded Mg-7Sn alloy is the highest, i.e., 255 MPa, increased by 120% as compared with that of as-cast samples.

关键词： Mg-Sn alloy extrusion tensile property microstructure

EFFECTS OF MAGNETIC FIELD STRENGTH ON MICROSTRUCTURE AND texture EVOLUTION IN COLD-ROLLED INTERSTI-TIAL-FREE STEEL BY MAGNETIC FIELD ANNEALING

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Acta Metallurgica Sinica(English Letters) 2008年第2期21卷 103-108页

作者： T.Watanabe key laboratory for anisotropy and texture of materials (Ministry of Education) Northeastern University

Effects of magnetic field strength on the evolution of recrystallization microstructure and recrystallization texture in cold-rolled interstitial-flee steel were investigated after annealing at 660℃ in a magnetic field up to 12 T. Magnetic annealing was found to retard recrystallization and induce recrystallized grains elongated along the magnetic field direction. An interesting phenomenon is that the magnetic field shows the strongest effect at 1 T.

关键词： Magnetic annealing Recrystallization texture Interstitial-freesteel

Microstructure,Mechanical Properties and Corrosion Behavior of Extruded Mg–Zn–Ag Alloys with Single-Phase Structure

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Acta Metallurgica Sinica(English Letters) 2018年第6期31卷 575-583页

作者： Hong Zhao Li-Qing Wang Yu-Ping Ren Bo Yang Song Li Gao-Wu Qin key laboratory for anisotropy and texture of materials Ministry of EducationSchool of Materials Science and EngineeringNortheastern University

Mg–Zn–Ag alloys have been extensively studied in recent years for potential biodegradable implants due to their unique mechanical properties,biodegradability and *** the present study,Mg–3Zn-x Ag（wt%,x=0.2,0.5 and0.8）alloys with single-phase crystal structure were prepared by backward extrusion at 340°*** addition of Ag element into Mg–3Zn slightly influences the ultimate tensile strength and microstructure,but the elongation firstly increases from12%to 19.8%and then decreases from 19.8%to 9.9%with the increment of Ag *** tensile yield strength,ultimate tensile strength and elongation of Mg–3Zn–0.2Ag alloy reach up to 142,234 MPa and 19.8%,respectively,which are the best mechanical performance of Mg–Zn–Ag alloys in the present *** extruded Mg–3Zn–0.2Ag alloy also possesses the best corrosion behavior with the corresponding corrosion rate of 3.2 mm/year in immersion test,which could be explained by the single-phase and uniformly distributed grain structure,and the fewer twinning.

关键词： Mg–Zn–Ag Single phase Backward extrusion Mechanical performance Corrosion behavior

Microstructure,Mechanical Properties and Fracture Behavior of As-Extruded Zn-Mg Binary Alloys

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Acta Metallurgica Sinica(English Letters) 2017年第10期30卷 931-940页

作者： Li-Qing Wang Yu-Ping Ren Shi-Neng Sun Hong Zhao Song Li Gao-Wu Qin key laboratory for anisotropy and texture of materials (Ministry of Education) School of Materials Science and EngineeringNortheastern University

In the present work, Zn-（0-1）Mg（wt%） alloys were prepared by casting and indirect extrusion at 200 and300 ℃, respectively. With Mg addition, both the size and amount of second phase Mg2Zn（11） increased, and the equiaxed grains were significantly refined. The extrusion temperature had little influence on Mg2Zn（11）, but the grains were refined at low extrusion temperature. For the alloys extruded at 200 ℃, as Mg content increased, the tensile yield strength（TYS）increased from 64 MPa for pure Zn to 262 MPa for Zn-1Mg; the elongation increased from 14.3% for pure Zn to 25% for Zn-0.02Mg and then decreased to 5% for Zn-1Mg. For the alloys extruded at 300 ℃, as Mg content increased, the TYS increased from 67 MPa for pure Zn to 252 MPa for Zn-1Mg, while the elongation decreased from 11.7% to 2%. The alloy extruded at 200 ℃ exhibited higher TYS and elongation than the corresponding alloy extruded at 300 ℃. The combination of grain refinement and second phase Mg2Zn（11） contributed to the improvement in the TYS, and the grain refinement played a major role in strengthening alloy. Zn-0.02Mg and Zn-0.05Mg alloys extruded at 200 ℃ show a mixture of cleavage and ductile fracture corresponding to higher elongation, while the other alloys show cleavage fracture.

关键词： Zn-Mg binary alloy Indirect extrusion Microstructure Mechanical property Fracture behavior

Assessment of Co-Cr-Ni ternary system by CALPHAD technique

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Rare Metals 2012年第1期31卷 75-80页

作者： Yang, Shuyu Jiang, Min Li, Hongxiao Liu, Yang Wang, Lei key laboratory for anisotropy and texture of materials Ministry of Education Northeastern University Shenyang 110004 China

The Co-Cr-Ni ternary system was critically assessed using the CALPHAD *** solution phases including the liquid,γ(Co,Ni),εCo and αCr phases were described by a substitutional solution ***·phase was characterized by a three-sublattice model of (Co,Ni)8Cr4(Co,Cr,Ni)18 in order to reproduce its homogeneity range determined by experiments.A self-consistent set of thermodynamic parameters for each phase was derived.

关键词： Co-Cr-Ni phase diagram CALPHAD Co-based superalloys alloy design