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Zhouhua Jiang Huabing Li Zhaoping Chen Zongze Huang Deling Zou Lianke Liang 《国际钢铁研究》2005,76(10):740-745
Nitrogen solubility in the austenitic stainless steel melts was measured in the laboratory by bubbling nitrogen gas under different partial pressures of nitrogen and temperatures. A new thermodynamic model for the calculation of nitrogen solubility in molten stainless steel in a wide range of alloy concentrations, temperatures, and pressures has been successfully established by introducing a new term for the effect of pressure on the nitrogen activity coefficient. The calculation results were in good agreement with the measured values. The influences of temperature, nitrogen partial pressure and chemical composition on the nitrogen solubility in molten stainless steel are discussed based on the calculated results. It is possible to produce high nitrogen steels at normal pressure by optimizing the design of the alloy composition and controlling the lowest melting temperature from a thermodynamic point of view. 相似文献
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In this study the influence of Mn on galvannealed coatings of 1.7% Mn‐1.5% Al TRIP‐ and 23% Mn X‐IP®‐steels was investigated. It is shown that the external selective oxides like Mn, Al and Si of the TRIP steel which occur after annealing at 800 °C for 60 s at a dew point (DP) of ‐25 °C (5% H2) hamper the Fe/Zn‐reaction during subsequent galvannealing. Preoxidation was beneficially utilized to increase the surface‐reactivity of the TRIP steel under the same dew point conditions. The influence of Mn on the steel alloy was investigated by using a 23% Mn containing X‐IP®‐steel which was bright annealed at 1100 °C for 60 s at DP ‐50 °C (5% H2) to obtain a mainly oxide free surface prior to hot dip galvanizing (hdg) and subsequent galvannealing. As well known from the literature Mn alloyed to the liquid zinc melt stabilizes δ‐phase at lower temperatures by participating in the Fe‐Zn‐phase reactions, it was expected that the metallic Mn of the X‐IP®‐steel increases the Fe/Zn‐reactivity in the same manner. The approximation of the effective diffusion coefficient (Deff(Fe)) during galvannealing was found to be higher than compared to a low alloyed steel reference. Contrary to the expectation no increased Fe/Zn‐reaction was found by microscopic investigations. Residual η‐ and ζ‐phase fractions prove a hampered Fe/Zn‐reaction. As explanation for the observed hampered Fe/Zn‐reaction the lower Fe‐content of the high‐Mn‐alloyed X‐IP®‐steel was suggested as the dominating factor for galvannealing. 相似文献
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在高温高压反应釜内冶炼Cr12N高氮钢,通过试验发现,在Cr12N的熔炼过程中,随着压力的提高,钢中的氮含量不断增加,钢锭中得到的固相中氮的饱和溶解度和Chipman等人的热力学模型计算得到的氮的饱和溶解度有一定的偏差,为了修正这个偏差,引进了Burton-Prim-Slichter方程,修正后得到液相中氮的饱和溶解度的修正值和计算值吻合得很好。计算了在Cr12N的冶炼过程中,防止气泡析出所需要的最小凝固压力为2.84 MPa,通过试验发现,在高的凝固压力下,钢锭的致密性和缩孔现象得到明显改善。 相似文献
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The properties of high‐speed tool steels can be improved by modifying their chemical composition or the technology of production. Nitrogen alloying is an attractive technology to enhance the mechanical and physical properties of tool steels. In this work, modified super hard high‐speed tool steel was produced through nitrogen alloying and decreasing the level of cobalt content in investigated steels. This work aims to study the effect of nitrogen as alloying element on carbides and carbo‐nitrides precipitates type, shape, and size for investigated steels. From the results obtained from Thermo‐Calc, it was concluded that nitrogen alloying produced large amount of stable austenite, also eutectic carbides precipitates (M6C and M7C3) were stable at room temperature. Transmission electron microscope (TEM) images for traditional grade showed that the as cast structure contains beside the carbides network other single carbides precipitates. While on the other hand the selected area diffraction pattern (SADP) images of nitrogen alloyed grade shows fine carbides and carbo‐nitrides precipitates with more amount of retained austenite in the ferrite matrix, they showed also the presence of the eutectic precipitates as well as the dislocations. 相似文献
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In casting heavy ingots of high‐chromium high‐carbon cold work steels, macrosegregation develops in the center of the ingot, causing difficulties during subsequent hot working. Heat transfer and solidification of an industrial scale high‐carbon high‐chromium steel ingot was simulated and thereafter a laboratory scale representative ingot was designed to model the solidification of the industrial scale ingot. Titanium in the range of 0.3–1% was added to the high‐chromium high‐carbon (12%Cr–2%C) steel during melting process. Microstructures, macrosegregation and phase formations were studied using optical microscopy, scanning electron microscopy, energy dispersive X‐ray spectrometry, wave dispersive X‐ray spectrometry, optical emission spectroscopy, and X‐ray diffraction. Addition of 0.3% titanium was sufficient to diminish the macrosegregation; however it did not have a significant effect on the grain size. Addition of 0.7 and 1% titanium had a substantial effect on grain size in the longitudinal direction and refined the primary carbides structure. The formation of small TiC carbides that precipitated before solidification of liquid iron acted as nuclei for primary pro‐eutectic austenite grains. 相似文献
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氮气加压熔炼高氮钢若干理论问题探讨 总被引:5,自引:0,他引:5
导出了氮在铁合金溶液中的溶解度模型,探讨了表面活性元素对吸氮过程的影响,且对含氮铁合金溶液的凝固过程、氮的偏析及保持氮在熔体中的最小压力进行了精确解析。 相似文献
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The deformation behaviour of high‐nitrogen austenitic steels with the base composition of Fe‐18Cr‐10Mn containing various contents of nitrogen was investigated. Two deformation modes including deformation‐induced martensitic transformation (DIMT) and deformation twinning (DT) were observed depending on the nitrogen content. In the alloys with lower nitrogen contents, γ→?→α' martensitic transformation sequentially occurred, whereas DT acted as a main deformation mode and DIMT was suppressed in the alloys with increasing nitrogen content. Both DIMT and DT showed strong crystallographic orientation dependence. The competing mechanism between them was discussed in terms of the variation of stacking fault energy with nitrogen content. 相似文献
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高氮不锈钢研究的发展近况 总被引:4,自引:0,他引:4
介绍了国内外高氮不锈钢研究近期的成果,内容涉及高氮不锈钢基础研究、力学性能、耐腐蚀性能、焊接性及高氮不锈钢新材料,反映了国内外高氮不锈钢研究的发展状况.鉴于高氮不锈钢卓越的综合性能而国内高氮钢研究已远远落后于国际发展水平的现状,应尽快在国内建立高氮钢试验装置,加快国内高氮不锈钢基础理论、生产工艺技术(特别是冶炼技术)和新材料的研究,把握不锈钢发展的方向,为中国不锈钢的发展提供有力的支持. 相似文献
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During the continuous casting of high‐Al steel, the dynamic reduction of silica‐based mould fluxes by the aluminium in the steel leads to changes in their composition and physical properties. The alumina‐based mould flux has been suggested as an alternative to alleviate this reduction problem. However, until now, the smooth running of high‐Al steel continuous casting has been impeded by the lack of systematic investigation of properties of this slag. In this paper, the effects of typical components on the properties of alumina‐based mould fluxes are discussed. The experimental results show that: (a) an increase in F? can reduce the viscosity while increasing the melting and break temperatures; (b) with increasing Li2O, the viscosity, melting temperature, and break temperature first decrease and then increase; (c) with the addition of BaO, the viscosity, melting temperature, and break temperature remain at a low level, while a further increase in BaO causes a decrease in viscosity, an increase in melting temperature, and the stabilization of the break temperature; (d) BaO is favorable to stabilize the properties of mould fluxes for the dissolution of additional Al2O3; (e) the crystalline phases of the mould fluxes mainly contain 12CaO · 7Al2O3 and 11CaO · 7Al2O3 · CaF2, and 12CaO · 7Al2O3 has great potential as a substitute for cuspidine. 相似文献