Hua HOU
,
Dong-Ying Ju
,
Yuhong ZHAO
,
Jun CHENG
材料科学技术（英）
Two-dimensional numerical simulation for the dendrite growth of binary alloy during solidification is carried out by a phase field method. In the model equations, phase field, temperature and solute redistribution are all involved. The equations are solved using the finite difference method (FDM) with two different space steps of phase field and temperature field. In calculation, the thermal noise is introduced to generate the side branches; the dependence of dendrite growth on the space step was also investigated. It is shown that thermal noise can trigger the growth of side-branches, however it has no influence on the stable behavior of the dendrite tip; the feature of dendrite growth is reasonable with δ Δx≤0.6W0, Δx is the space step and W0 is the thickness of interface.
关键词:
Phase field
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null
,
null
Lin HU
,
Xiaodong HU
,
Peng GAO
,
Hongyang ZHAO
,
Dong-Ying Ju
材料科学技术（英）
Based on the discussing of the mechanisms of grain refinement strengthening and deformation induced transformation, the characteristics of controlled rolling and controlled cooling for high-speed wire were analyzed. Aiming at the problems of wire mill in Anshan Iron & Steel Co., turbulent cooler and spray cooler on the Stelmor conveyor were developed. Super-steels had been developed for Q235 steel through unrecrystallized austenite region rolling. The constitution and properties of the wire on the coil overlap zone were also improved. This proved the possibility that super-steels can be developed in high-speed wire mill.
关键词:
Super-steel
,
null
,
null
,
null
Ming QIN
,
Dong-Ying Ju
,
Yan ZHANG
,
Pei BIAN
材料科学技术（英）
The previous work has indicated that the carburizing-quenching process is often accompanied by the decarburization in the surficial layer of mechanical parts. A numerical model based on “metallo-thermo-mechanics” was used to estimate the microstructure and residual stresses in the case layer of a carburizing-quenched SCr420 steel. In order to verify above model, the experimental methods, such as XRD, color metallography, microhardness indentation, and EPMA, are also used to analyze the correlative parameters. The decarburization in the carburizing-quenched SCr420 steel was observed, and the simulation results are a little different from the experimental results. According to the results, the factors of reducing the accuracy of the numerical simulation method have been discussed.
关键词:
Decarburization
,
null
,
null
P.Bian
,
Dong-Ying Ju
材料科学技术（英）
Magnetite (Fe3O4) of ferrite magnetic materials has attracted attentions arising by the chip coil electronic material. However, its industrial applications have been limited by the need of high temperature sintering under reduced pressure or vacuum. In order to develop the process method of low-cost and energy saving with high strength and high magnetism of the magnet, a new low temperature sintering method during CO2 gas and adding small amount of boric acid (H3BO3) are proposed. Here, the superfine magnetite powder was fabricated by decomposition from ferrous oxalate at 500℃ in CO2 gas. The ferrous oxalate was synthesized using iron chloride and ammonium oxalate with the liquid phase precipitation. The magnetite powder compact was produced by Newton press and CIP (cold isostatic press) after adding small amount of boric acid. In this study, the effects of the additive on the mechanical and magnetic properties of the sintered magnet were also evaluated. By characteristic evaluation of the magnet, the validity of the proposed new low-temperature sintering process and the optimal process conditions were confirmed.
关键词:
Ferrite magnet
,
null
,
null
,
null
Hongyang ZHAO
,
Dong-Ying Ju
,
Lin HU
材料科学技术（英）
The twin-roll casting (TC) process of Al alloy was presented. Microstructure and crystallization of the as-cast strip are investigated to link the strip quality and microstructure with the process conditions. The process variables of cooling rate, temperature history and solidification finish point and their influences are discussed. The results revealed the ability of the twin-roll caster to produce directly the thin strip of Al alloy with improved mechanical strength.
关键词:
Twin-roll
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null
,
null
,
null
