M. Naka
,
J. Zhang
,
H. Y. Fang (1.Joining and Welding Research Institute
,
Osaka University
,
Japan 2)School of Materials Science and Engingeering
,
Harbin institute of Technology
,
Harbin 150001
,
China)
金属学报(英文版)
St3N4 ceramic was brazed using a filler of Cu - Zn - Ti alloy under the brazing condition of 1223K and 1.8ks. When the Ti content in the alloy is 20% at., the average shear strength of the joint is 265MPa. By using EPMA and XRD analysis, the metallurgical behavior of the interface between the filler alloy and Si3N4 matrix was studied,which affected the joint strength.It was found that with in- creasing Ti content from 5% to 20%at., the thickness of the brazing seam decreases and the amount of the reactant(Ti5Si3, TiN and Ti2N etc. ) increases,resulting in an obvious increase of the shear strength of the joint.
关键词:
Si_3N_4 ceramic
,
null
,
null
,
null
,
null
R Paventhan
,
P R Lakshminarayanan
,
V Balasubramanian
钢铁研究学报(英文版)
Friction welding is a solid state joining process used extensively currently owing to its advantages such as low heat input, high production efficiency, ease of manufacture, and environment friendliness. Materials difficult to be welded by fusion welding processes can be successfully welded by friction welding. An attempt was made to develop an empirical relationship to predict the tensile strength of friction welded AISI 1040 grade medium carbon steel and AISI 304 austenitic stainless steel, incorporating the process parameters such as friction pressure, forging pressure, friction time and forging time, which have great influence on strength of the joints. Response surface methodology was applied to optimize the friction welding process parameters to attain maximum tensile strength of the joint. The maximum tensile strength of 543 MPa could be obtained for the joints fabricated under the welding conditions of friction pressure of 90 MPa, forging pressure of 90 MPa, friction time of 6 s and forging time of 6 s.
关键词:
friction welding
,
stainless steel
,
response surface methodology
,
optimization
Yan NIU
,
Weitao WU and Chaoliu ZENG (State Key Lab. for Corrosion and Protection
,
Institute of Corrosion and Protection of Metals
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)F. Gesmundo and F. Viani (Instituto di Chimica
,
Facolta di Ingegneria
,
Un
材料科学技术（英文）
The corrosion of an Fe-based alloy containing 15 wt pct Y in H2-H2S mixtures under 10-3 Pa S2 was studied at 600~800℃ in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneflcial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus,Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition. but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12~17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe
关键词:
材料科学技术（英文）
The corrosion of an Fe-based alloy containing 15 wt pet Y in H-2-H2S mixtures under 10(-3) Pa S-2 was studied at 600 similar to 800 degrees C in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneficial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus, Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition, but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12 similar to 17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe.
关键词:
high-temperature sulfidation;most-reactive component;ni-nb alloys;h2-h2s mixtures;behavior;600-degrees-c-800-degrees-c;oxidation
Chunli YANG
,
Sanbao LIN
,
Fengyao LIU
,
Lin WU
,
Qingtao ZHANG
材料科学技术（英文）
The mechanism of penetration depth increased by activating flux in activating tungsten inert gas (A-TIG) welding was studied by measuring the distribution of trace element Bi in the weld and monitoring the change of arc voltage during A-TIG welding of stainless steel 0Cr18Ni9 with fluxes SiO2 and TiO2. The results show that the mechanism of penetration depth in A-TIG welding depends on the sort of flux used. The weld pool convection after coating the flux SiO2 and flux TiO2 is changed inversely compared with convectional TIG welding without flux. The arc voltage is increased by flux SiO2 whilst flux TiO2 does not have effect on the arc voltage. The reason of penetration depth increase for SiO2 is due to the constriction of arc plasma and the change of surface tension gradient. The increase of weld penetration depth with TiO2 only ascribes to the change of surface tension gradient.
关键词:
TIG welding
,
null
,
null
,
null
Jiuba WEN
,
Yongshun YANG
材料科学技术（英文）
Superplastic welding of tool steel and structural steel was investigated. The welding between 40Cr and CrWMn steels was carried out under the conditions of temperature 750 similar to 780 degreesC, strain rate 2x10(-4) s(-1), compressive stress 50 similar to 90 MPa for 3 similar to5 min. The joints show similar strength to that of 40Cr steel and the good metallurgical joining is formed. The structural change occurring during superplastic welding was analyzed by metallography and distribution of carbon content in the vicinity of the welding joint was also determined. The mechanism of superplastic welding for steels is proposed to be the disappearance of original bond interfaces caused by atomic diffusion and the grain sliding.
关键词:
S.H. Dong
,
Y.M. Lu
金属学报(英文版)
Based on the theory of hydrogen enhanced localized plasticity of the hydrogen induced cracking and considered the effect of residual stress produced by eliminated stress heattreatment, a fractal model of hydrogen induced cracking was presented, and a relationship among the effective surface energy T( H), fractal dimension D and stress intensity factor of hydrogen induced cracking, KIH, for welding pipeline under hydrogen environment was set up, from which the relationship of D and KIsCC is obtained. The model was verified experimentally to be correct.
关键词:
hydrogen environment
,
null
,
null
,
null
,
null
C.Y. Choi D.C. Kim D.G. Nam Y.D. Kim Y.D. Park
材料科学技术（英文）
Currently, in the automotive industry, joining of the aluminum alloys with the steel is a crucial problem to be solved. Conventional joining techniques including resistance spot and gas metal arc welding are not acceptable for those applications due to a number of metallurgical problems. The investigation was carried out to develop the hybrid joining process combining the resistance spot welding and brazing. In this study, an attempt was made to apply hybrid process to the joining of dissimilar sheet metals, Al-Mg-Si (6000 series) alloy and low carbon steel sheet. Hybrid process (resistance spot weld/brazing) using filler metal was found to be effective to overcome the incompatibility between aluminum alloy and steel. Although hybrid joining process of Al alloy sheet and steel sheet did not produce acceptable bond strength, it was proved to have reasonable interfacial
bond layer if the optimal process condition was applied.
关键词:
Hybrid joining
,
Aluminum
,
Steel
,
Welding
C.Y. Choi D.C. Kim D.G. Nam Y.D. Kim Y.D. Park
材料科学技术（英文）
Currently, in the automotive industry, joining of the aluminum alloys with the steel is a crucial problem to be solved. Conventional joining techniques including resistance spot and gas metal arc welding are not acceptable for those applications due to a number of metallurgical problems. The investigation was carried out to develop the hybrid joining process combining the resistance spot welding and brazing. In this study, an attempt was made to apply hybrid process to the joining of dissimilar sheet metals, Al-Mg-Si (6000 series) alloy and low carbon steel sheet. Hybrid process (resistance spot weld/brazing) using filler metal was found to be effective to overcome the incompatibility between aluminum alloy and steel. Although hybrid joining process of Al alloy sheet and steel sheet did not produce acceptable bond strength, it was proved to have reasonable interfacial
bond layer if the optimal process condition was applied.
关键词:
Hybrid joining
,
Aluminum
,
Steel
,
Welding
