C.Y. Choi D.C. Kim D.G. Nam Y.D. Kim Y.D. Park
材料科学技术（英）
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
Zhijun JIA
金属学报(英文版)
The effect of calcium ions on the corrosion behavior of 3Cr low-alloy steel in CO2-containing sodium chloride solution was investigated by immersion test and electrochemical measurements. It is found that with the addition of Ca2+ to CO2-containing solution, the crazing level of the corrosion scale on the specimen is much slighter than that of the specimen immersed in solution without Ca2+. The pitting on the surface of the specimens immersed in the solution with Ca2+ is relatively small and distributes uniformly all over the surface. The significant change in the anodic polarization curve is attributed to the deposition of the CaCO3. CaCO3 deposits on the specimen surface and gives a protection to the metal substrate. And with the anodic proceeding, the concentration of H+ in the solution increases. The CaCO3 deposition dissolves in the low pH solution and the protection effect disappears.
关键词:
Steel
C.Y. Choi D.C. Kim D.G. Nam Y.D. Kim Y.D. Park
材料科学技术（英）
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
Houfa SHEN
,
Richard A.Hardin
,
Robert MacKenzie
,
C.Beckermann
材料科学技术（英）
A three-dimensional heat transfer model for continuous steel slab casting has been developed with realistic spray cooling patterns and a coupled microsegregation solidification model that calculates the solidification path for multi-component steels. Temperature and composition dependent properties are implemented in a database for 15 chemical species.Considerable effort is made to accurately model the spray cooling heat transfer. Each spray nozzle position and distribution is considered, including variations of the spray patterns with flow rate,and spray overlap. Nozzle type,layout, nozzle-to-slab distance, and spray span and flux are variable.Natural convection, thermal radiation and contact cooling of individual rolls are computed. The present model provides more comprehensive information and realistic slab surface temperatures than results from a model using the “averaged” treatment of boundary conditions. Cooling operating conditions and parameters of individual spray nozzles can be analyzed to optimize nozzle spray distribution, improve product quality, and troubleshoot issues such as nozzle clogging that may arise during production. One spray cooling correlation is used for the entire machine, achieving as good or better agreement with surface temperature measurements than was found previously for the model using an “averaged” treatment of boundary conditions and using three machine-segment-dependent correlations.
关键词:
Steel
,
null
,
null
Chunshan CHE
,
Jintang LU
,
Gang KONG
,
Qiaoyu XU
金属学报(英文版)
doi:DOI: 10.1016/S1006-7191(08)60
In this article, five kinds of silicon-containing steel sheets have been electrodeposited, and then immersed in a pure molten zinc bath at 450℃ for various periods of time. The results by scanning electron microscopy (SEM) show that the coating of the sample (0.09 wt pct Si) with iron-electrodeposited pretreatment eliminates the reactive zones which are found in the coating without iron-electrodeposited pretreatment. The galvanized sample (0.28 wt pct Si) with iron-electrodeposited pretreatment exhibits a compact and coherent coating. The coating of the sample (0.37 wt pct Si) with the iron-electrodeposited pretreatment experiences a transition from a compact and coherent coating to a reactive one. The energy dispersive spectrum (EDS) results reveal that for the galvanized samples with iron-electrodeposited pretreatment, excessive silicon accumulates on the surface of the substrate due to the low solubility of silicon in the τ, after the iron layer is depleted by the increasing growth of the Fe-Zn intermetallics. With the movement of the substrate/τ interface toward the substrate, silicon-enriched α-Fe peels off from the substrate and breaks into the particles. The particles move toward the δ layer through the τ layer because silicon-enriched α-Fe cannot be absorbed in the τ layer. When the particles reach the δ/τ interface, they are dissolved in the δ layer, making the τlayer thin or even vanish.
关键词:
Zn coating
,
null
,
null
,
null
,
null
