巻号一覧
79 巻, 3 号
選択された号の論文の9件中1～9を表示しています
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論説
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植田 茂紀, 清水 哲也, 梶原 正憲2008 年 79 巻 3 号 p. 177-185
発行日: 2008/08/25
公開日: 2008/12/26
ジャーナル フリーA Ni-38 mass% Cr-3.8 mass% Al alloy possesses higher hardness and tensile strength than conventional Ni-base alloys. Such excellent properties are attributed to the discontinuous or cellular precipitation of the Cr-rich solid-solution (α) phase with the body-centered cubic (bcc) structure combined with the continuous precipitation of the Ni3Al (γ’) phase with the L12 structure from the Ni-rich solid-solution (γ) phase with the face-centered cubic (fcc) structure. Due to the cellular precipitation, the untransformed matrix of the γ phase is transformed into the cell consisting of the γ and α lamellae dispersed with fine γ’ particles. Since the growth of the cell is controlled by the boundary diffusion along the moving boundary between the cell and the untransformed matrix, it occurs rather fast. In such a case, it is not easy to realize the uniformly transformed cell over the whole area of the alloy with a large size. In order to find the alloying element inhibiting the growth of the cell, the influence of Mo, W and Fe on the kinetics of the cellular precipitation was experimentally observed using Ni-Cr-Al alloys with 35-36 mass% Cr and 3.8 mass% Al containing 1-2 mass% Mo, 1-2 mass% W or 5 mass% Fe. According to the observation, the overall growth of the cell is decelerated by Mo and W, but accelerated by Fe. Furthermore, the influence is more remarkable for Mo than for W. Thus, Mo is one of the most effective alloying elements suppressing the growth of the cell.抄録全体を表示PDF形式でダウンロード (815K) -
成田 修二, 植田 茂紀, 清水 哲也2008 年 79 巻 3 号 p. 187-196
発行日: 2008/08/25
公開日: 2008/12/26
ジャーナル フリーNitrogen is one of the effective elements to enhance strength, corrosion resistance and austenite stability of stainless steel. Recently many studies have been conducted about nitrogen bearing austenitic, duplex and martensitic stainless steels. In this study, high nitrogen martensitic stainless steels containing 0.5C-0.2N, 0.3C-0.4N and 0.1-0.6N (; mass%) have been produced through the pressurized induction melting process. The hardness and corrosion resistance of the experimental steels have been investigated in various heat treatment conditions. The obtained results are as follows. (1) The maximum hardness of the steels after hardening with sub-zero treatment increases with carbon content, and the volume fraction of their retained austenite increases with nitrogen content. (2) In tempering process, all the steels show obvious secondary hardening at 723-773 K, and the maximum hardness increases with nitrogen content. Change in hardness of martensite after tempering at 723 K increases with [mass%N(in matrix)], ΔH723 K = 24.7 · [mass%N(in matrix)]-7.2 [HRC] where [mass%N(in matrix)] : nitrogen content in solid solution of as-quenched material. (3) The corrosion resistance of the steels after tempering is deteriorated with increasing tempering temperature. The steels containing more than 0.4 mass%N tempered under 723 K have corrosion resistance comparable with that of TYPE304 evaluated by pitting potential in 3.5 % NaCl aqueous solution.抄録全体を表示PDF形式でダウンロード (554K) -
大崎 元嗣, 植田 茂紀, 清水 哲也, 大森 俊洋, 石田 清仁2008 年 79 巻 3 号 p. 197-205
発行日: 2008/08/25
公開日: 2008/12/26
ジャーナル フリーCo-base superalloy has been generally strengthened through solid solution hardening and/or carbide precipitation hardening because dominant L12-γ’ phase has not been found as like L12-Ni3Al, which has been major strengthening phase for Ni-base superalloy. However, recently, γ’-Co3(W,Al) was found in Co-W-Al ternary alloy. Thereby new γ’ strengthening Co-base superalloy is expected. In this work, properties of four kinds of γ’ strengthening Co-W-Al alloys with the amount of γ’ phase from 20 % to 50 % on calculation were investigated and the following results were obtained. (1) High temperature ductility was decreased and flow stress was increased with increasing γ’ phase forming elements which were W, Al and Ta. Excessive additions of γ’ phase forming elements degraded the high temperature ductility drastically due to the precipitation of μ phase. (2) γ’ solvus temperature and nose temperature of peak aging hardness shifted to higher temperature by increasing γ’ phase forming elements. The alloy with 40 % γ’ phase showed adequate hot workability possessed 360 HV as peak aging hardness around 1073 K. (3) The oxidation resistance of alloys with 5 mol% Cr was improved by increasing Al content up to 9 mol%. However it is insufficient in order to form the homogeneous protective scale layer of Al2O3 and Cr2O3 at 1273 K.抄録全体を表示PDF形式でダウンロード (903K) -
小川 道治, 野田 俊治, 土井 智史, 上田 正人, 池田 勝彦2008 年 79 巻 3 号 p. 207-216
発行日: 2008/08/25
公開日: 2008/12/26
ジャーナル フリーBy virtue of their high strength and excellent cold workability, β titanium alloys have been used for various applications, e.g. parts of airplanes and eyeglass frames. Generally, β titanium alloys contain vanadium and molybdenum as alloying elements. However, the official quotations of vanadium and molybdenum are unstable. Therefore, use of those alloying elements is limited. We adopted chromium and iron, whose official quotations are more stable than those of vanadium and molybdenum, and reported some parts of the research of Ti-13Cr-1Fe-3Al alloy. Cr is one of the attractive elements to develop the cost affordable titanium alloys. Thus, it is very important to investigate the Ti-Cr binary alloys as basic study. It is also important to study the heat treatment behavior of the Ti-Cr alloys. In this study, phase constitution and isothermal aging behavior of Ti-Cr alloys was investigated by measurements of electrical resistivity and Vickers hardness, X-ray diffraction, optical and scanning electron microscope observations and tensile tests. The obtained results are as follows. In solution treated and quenched stated (STQed) state, hcp martensite, α’ was only identified at 3Cr alloy. β phase and α’ were identified at 5Cr alloys. Above 5Cr, β phase was identified. In 7Cr and 10Cr, athermal ω was also identified. Maximum of HV appeared at 7Cr and then HV decreased with increase of Cr content up to 15Cr. Above 15Cr, HV slightly increased due to solution hardening by Cr addition. On isothermal aging, precipitation of the α phase was delayed by Cr addition. In STQed state, tensile strength is 961 MPa in 10Cr, 988 MPa in 13Cr and 967 MPa in 15Cr, respectively. Elongation is 27.1 % in 10Cr, 26.8 % in 13Cr and 23.9 % in 15Cr, respectively. In 15Cr alloy, nominal stress-nominal strain curve showed work-softening phenomenon after yield stress, whereas S-S curve of 10Cr alloy did not show that phenomenon. In 773 K-12 ks aged state, tensile test specimens of 10Cr and 13Cr were broken with no elongation, while the specimen of 15Cr alloy was broken after about 5 % in elongation. It is considered that difference of tensile properties between the 15Cr and others is due to differences of shape and volume fraction of precipitated α.抄録全体を表示PDF形式でダウンロード (1055K)
解説
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大沼 正人, 鈴木 淳市2008 年 79 巻 3 号 p. 217-227
発行日: 2008/08/25
公開日: 2008/12/26
ジャーナル フリーSmall-angle scattering is one of simplest methods to evaluate the average size and volume fraction of precipitates in the metals and alloys. The accuracy of the evaluated size is higher than 5 % if the analysis is proceeded in the proper way. In comparison with powder diffraction, however, there are some differences in the way to measure and analyze the small-angle scattering although the principle of the phenomena are same in both way. The key issues for measurements and analysis of small-angle scattering are overviewed and the results for high nitrogen martensitic steel are shown as an example.抄録全体を表示PDF形式でダウンロード (595K) -
黒田 健介, 市野 良一, 興戸 正純2008 年 79 巻 3 号 p. 229-237
発行日: 2008/08/25
公開日: 2008/12/26
ジャーナル フリーMany techniques for the surface modification of titanium and its alloy have been proposed from the viewpoint of the improvement of the bioactivity. This review contains an overview of the methods of surface treatments such as coatings with osteoconductive compounds, e.g., hydroxyapatite (HAp) and titania. Coating methods are classified into following two groups; pyro-processing and hydro-processing. In this review, we mainly outlined the hydro-processing for the coating of the HAp and titania on the titanium substrate. And also, mentioned the processing to create the metallic surface with fine and coarse roughness. Moreover, the evaluation by the implantation of the surface-modified samples in the rats’ tibia was explained.抄録全体を表示PDF形式でダウンロード (694K)
技術資料
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倉田 征児, 植田 茂紀, 野田 俊治, 山本 隆一, 角屋 好邦, 中野 隆, 田中 良典, 馬越 龍太郎2008 年 79 巻 3 号 p. 239-244
発行日: 2008/08/25
公開日: 2008/12/26
ジャーナル フリーAdvanced 700 ℃ class steam turbines require using Ni-based superalloys instead of conventional ferritic 12Cr steel which is insufficient in creep strength and oxidation resistance above 650 ℃. The superalloys, however, possess quite higher coefficient of thermal expansion (CTE) than the 12Cr steel. So far authors examined the influence of alloying elements on CTE and the high temperature strength of the Ni-based superalloys. Consequently “LTES700R” was developed for steam turbine, which has low CTE and sufficient creep strength. LTES700R is corrected Mo amount to inhibit the Laves phase and added W to reduce CTE instead of Mo within the range that alfa-tungsten does not precipitate. In addition, Al and Ti, which form gamma-prime, were increased to make up for deteriorating of the strength by Laves phase free. The creep rapture strength of LTES700R manufactured by laboratory forging is higher than that of advanced 12Cr steel owing to be strengthened by gamma-prime [Ni3(Al, Ti)] phase precipitates. The CTE of LTES700R is lower than that of Refractaloy 26®, and slightly higher than that of 12Cr steel. The phase of LTES700R is stable until 5000 hr heating from 550 ℃ to 750 ℃.抄録全体を表示PDF形式でダウンロード (472K) -
植益 広, 竹中 雅志, 清水 哲也, 山路 徹, 審良 善和2008 年 79 巻 3 号 p. 245-251
発行日: 2008/08/25
公開日: 2008/12/26
ジャーナル フリーCorrosion tests of 10 kinds of stainless steels were conducted for 10 years under two conditions of marine environments, which are atmospheric corrosion and intermittent seawater immersion. Rating numbers in 10 year test were almost same as those in 5 year test. Maximum pit depths in 10 year test were larger than those in 5 year test, especially in the case of steels with low PRE (Cr+3.3Mo+16N;mass%) value in atmospheric corrosion. It was confirmed that the progress of corrosion mainly depended on the pit growth. PRE value is correlated with both rating number and maximum pit depth. With higher PRE values, rating numbers were getting higher and maximum pit depths were getting lower. The steels of which PRE value was more than 37 showed excellent corrosion resistance under marine environment.抄録全体を表示PDF形式でダウンロード (437K) -
小川 道治, 清水 哲也, 野田 俊治, 鈴木 昭弘, 福田 達雄2008 年 79 巻 3 号 p. 253-257
発行日: 2008/08/25
公開日: 2008/12/26
ジャーナル フリーBy virtue of their high strength and low density, α+β titanium alloys have been used for various applications, such as airplanes and consumer products. Ti-6Al-4V alloy is one of the most popular α+β titanium alloys. Ti-6Al-4V alloy contains vanadium as alloying element. However, the official quotation of vanadium is not stable, limiting their usefulness as alloying elements. We adopted iron, whose official quotation is more stable than this of vanadium, and developed Ti-6Al-1Fe alloy, VLTi. The tensile and fatigue properties of VLTi are comparable with Ti-6Al-4V. Therefore VLTi could be used for the applications substituting for Ti-6Al-4V such as consumer products and automobile components. Moreover VLTi with lower density than Ti-6Al-4V is a suitable Ti alloy for golf head.抄録全体を表示PDF形式でダウンロード (279K)
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