Showing papers in "Tetsu To Hagane-journal of The Iron and Steel Institute of Japan in 1968"

Thermodynamic Properties of Niobium Carbides and Nitrides in Steels

Abstract: Synopsis: The crystallographic structure and the chemical composition of precipitated-ƒÂ-phase, ƒÂ'-phase and ƒÃ -phase were extensively investigated on those specimens which had been prepared from vacuum melted high-purity Fe-Nb-C, Fe-Nb-N and Fe-Nb-C-N alloys containing niobium up to 0.95%. The specimens were solution treated at 1300 or 1350•Ž for 2hr, and then these were again quenched into water after long time holding at respective temperatures of 1000 to 1300•Ž. The quantitative determination of soluble-niobium, -carbon and -nitrogen was also investigated in order to calculate the solubility products of niobium-carbide and -nitride in austenite. Results obtained are as follows; 1) The chemical composition of pure ƒÂ-niobium-carbide precipitates was determined to be NbC0 .87 though the precipitated ƒÂ-phase was not pure carbide but carbonitride even in the Fe-Nb-C alloys containing little nitrogen. 2) The precipitated ƒÂ'-nitride in Fe-Nb-N alloys containing little carbon was substantially carbonitride containing a little amount of carbon, while the precipitated ƒÃ-nitride was estimated to be a pure niobium-nitride NbN. 3) The solubility products of niobium-carbide and -nitride in austenite were given respectively by the following equations;

Studies on the Rate of Absorption of Nitrogen in Liquid Iron Containing Surface Active Elements

Abstract: Synopsis: The rates of absorption of nitrogen in liquid iron containing surface active elements, such as oxygen .and sulphur, were measured at 1550•Ž and 1600•Ž. The transfer of nitrogen across the gas-metal interface was remarkably disturbed by those surface .active elements, adsorbed on the surface of the metal. It was also recognized that the rates of absorption in those melts were proportional to the partial pressure of nitrogen, when the metal contained more than nearly 0.03% sulphur or oxygen. Furthermore, it was observed that the rates of absorption were inversely proportional to 2/3 power of sulphur (or oxygen) concentration in the bulk Contains higher than 0.03%S (or 0.02%O). These concentrations correspond to the coverage of the surface by sulphur or oxygen nearly as FeS or Fe, calculated by the Gibbs' adsorption equation. It becomes

Diffusion in Iron Oxide Melts

Abstract: The interdij!usivities of iron and ox)'gen in iron oxide melts have been measured by the capillary method over the temperature range from 1 430° to 1 550°C and the composition range from r( = Fe3+ / ~" Fe ) = 0.12 to 0.42. At 1 550°C, the interdiffusivity is 4 X 10' to 5 x 105 cIll2 /sec, which is very high as com/Jared with the diffusivities of silicate slags. Activation energies for diffusion are 10.7±0.6 and 16.6±0.2kcal/mol at 1' = 0.12 and 0.33, respectively . The diffusivity decreases with increase of r. At higher Fe3+ content (r> to 0.25) , this decrease of diffusivity becomes more conspicuous. The observed reslllts arc interpreted in relation to the cOllstitution of the melts and other /Jroperties sllch as electrical condllctivity and viscosity.

On Japanese Industrial Standard

Abstract: 規格は,そ れが適用 され る地域的あ るいは組織的な範 囲 によつて,一 国家の領土内で適用 され る国家規格,事 業者の団体内部で適用 され る団体規格,企 業の内部で適 用 され る社内規格な どに分 けられ,さ らに規格に規定 す る内容 によつ て,製 品の形状,寸 法,材 質,機 能な どを 規定す る製品規格,試 験方法,検 査方式な どを規定する 方法規格,用 語,標 準数,単 位な どを規定す る基本規格 に大別 される. Jlsは 工業標準化法(昭 和24年7月1日 施行)に 基 づ いて政府 によって制定 され る国家規格 で,内 容 的に も前 述の製 品規格,方 法規格お よび基本規格 を包含 してお り 正 式には 日本工業規格(Japanese Industrial Standard) と呼ばれ るものである. 規格 は,で きうれば生産者,消 費者,販 売者な ど関係 者の合意 によって作られ るのが望 ましいが,わ が国のよ うに,欧 米諸国 と比較 して工業技術の発達がお くれ,か っ,社 会的,経 済的 に関係者 の利 害があま りに も複雑 に 入 り交つ ていて,こ れ を相互 に調整で きる民間機関がな い場合 には,結 局政府 によつて統一的 に規格を制定す る のが工業標準化 を推進 してい く上 にとつて最 も効果的 な 方法 であ ろう.し か し政府が独善的 な規格を押 し付ける ような ことがあつてはい けないので,後 述す るような民 主的な手続が とられ実質的な利害関係者の意向が十 分に 反映で きる仕組み になつている. さらに規格は,固 定 した不 動の ものではな く,工 業技 術 の進歩 に即応 して改廃す る必要が あるが,こ の点でも Jlsは 少な くとも3年 ごとに見直す(法15条)こ とによ っ て常 に適正かつ台理的な規格 を維持 してい る.

Activity of Silicon in Liquid Iron

Abstract: Synopsis: The activity of silicon in liquid iron has been studied at 1560=C by mean of the equilibrium, SiO (g)+H2 (g)=[Si]+H2O (g) At concentrations up to Nsi=0.07 in Fe-Si System, the slope d In ƒÁ si/dNsi has aconstant value of ƒÃ (Si) Si=12 . By use of free energy of formation of silica determined by Bowles et al. at high temperature, the activity coefficient T•‹s at infinite dilution of silicon has been derived, and ƒÁ•KSi is 8.7•~10-4. At concentrations up to Nv=0.05 in Fe-Si-V System, interaction parameterƒÃs(V)Si has a value of 5.3.