巻号一覧
77 巻, 2 号
選択された号の論文の8件中1～8を表示しています
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論説
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濱野 修次, 清水 哲也, 野田 俊治2006 年 77 巻 2 号 p. 107-115
発行日: 2006/05/31
公開日: 2006/11/30
ジャーナル フリーNitrogen is one of the most effective elements for improving not only the strength but also the corrosion resistance of stainless steels. In this study, three low carbon and high nitrogen martensitic stainless steels, which contain less than 0.1 mass% C and more than 0.45 mass% N, have been produced through the pressurized induction melting process, in which nitrogen is introduced from the pressurized N2 atmosphere. The hardness and corrosion resistance of these steels were mainly investigated in various heat treatment conditions. The hardness of these steels after spheroidal annealing treatment was about 95 HRB and the cold workability was superior to that of AISI440C, which was a high carbon martensitic stainless steel. The hardness of these steels after hardening and sub-zero treatment was about 53 to 56 HRC, which was lower than that of high carbon martensitic stainless steel. In tempering process, however, high nitrogen steels showed the secondary hardening by about 4 point in HRC compared with the quenched hardness after sub-zero treatment and had the maximum tempered hardness of 56 to 60 HRC at around 723 K. The corrosion resistance of hardened and tempered materials under 723 K exhibited better than that of AISI304 evaluated by pitting potential in 3.5 % NaCl aqueous solution. Both remained Cr2N in hardening and precipitated Cr2N in tempering were found to degrade the corrosion resistance of high nitrogen martensitic stainless steels. The best balanced developed steel had the hardness of 60 HRC and better corrosion resistance than AISI304 at the same time under the optimized heat treatment condition.抄録全体を表示PDF形式でダウンロード (563K) -
小川 道治, 清水 哲也, 野田 俊治, 池田 勝彦2006 年 77 巻 2 号 p. 117-122
発行日: 2006/05/31
公開日: 2006/11/30
ジャーナル フリーβ titanium alloys such as Ti-22mass%V-4mass%Al, Ti-15mass%V-3mass%Cr-3mass%Sn-3mass%Al have high strength and excellent cold workability, so that the alloys have been used for the materials of golf club head, the frame of glasses, fasteners and so on. However it is necessary to lower the price of the alloys in order to accelerate the expansion of the application. It is the one of the effective way to substitute iron and chrominum for high-cost alloying elements like vanadium as β phase stabilization. So far we have found out that Ti-13 mass%Cr-1.2 mass%Fe-Al had the comparable tensile properties to the conventional alloys. In this study, the effect of aluminum content on the phase constitution of Ti-Cr-Fe alloys was investigated by measurements of electrical resistivity and Vickers hardness, X-ray diffraction and transmission electron microscope observation. The results obtained are as follows. In the solution treated and quenched state (STQ), resistivity(ρ) at liquid nitrogen(LN) and room temperatures(RT) increased monotonously with aluminium content. 0 %Al and 3.0 %Al alloys consisted of β phase and athermal ω. In the isochronal heat treatment, two minima of resistivity were observed at 623 K and 823 K. The former is due to the precipitation of isothermal ω phase and the latter is α precipitation. The temperature of resistivity minimum attributing to ω phase precipitation gradually increases with increasing of aluminium content. In 4.5 %Al and more, the minimum of resistivity by ω precipitation disappears and the minimum caused by ω precipitation remained. It is considered that aluminium content above 4.5 % was suppressed ω precipitation and enhanced α precipitation.抄録全体を表示PDF形式でダウンロード (352K) -
高林 宏之, 清水 哲也2006 年 77 巻 2 号 p. 123-132
発行日: 2006/05/31
公開日: 2006/11/30
ジャーナル フリーRecently magnesium alloys sheets have been widely applied to the chassis of electronics appliances such as laptop PCs, cellular phones, digital cameras. So far AZ31(Mg-3 mass%Al-1 mass%Zn) with relatively good hot-workability has been used for the material of such applications. On the other hand higher strength sheets are strongly required because high rigidity and stiffness are necessary to the chassis with smaller form factors. In this study the effect of heat treatment and small amount of calcium addition up to 0.03 mass% on the hot-workability of cast AZ61(Mg-6 mass%Al-1 mass%Zn) alloy was investigated. Although AZ61 has poor hot-workability in the as-cast condition, it drastically improves by heat treatment at 673 K for 360 ks because of the dissolution of β-Mg17Al12 phase that becomes the origin of crack. Heat treated AZ61 with small amount of calcium addition has better hot-workability than that without calcium addition. That is due to the suppression of grain growth in the heat treatment by existing calcium bearing inclusions as small particles with pinning effect. The hot workability of AZ61 with 0.01 mass% calcium is as good as that of AZ31, a conventional magnesium alloy for hot rolling.抄録全体を表示PDF形式でダウンロード (878K) -
植田 茂紀, 清水 哲也, H.K.D.H. Bhadeshia2006 年 77 巻 2 号 p. 133-141
発行日: 2006/05/31
公開日: 2006/11/30
ジャーナル フリーNi-38Cr-3.8Al (mass%) and Ni-38Cr-4.2Al alloys have γ single phase and low hardness as approximately 200 HV in solution treatment condition. On the contrary, cellular precipitation, which consists of α-Cr and γ/γ′ initiates from grain boundary by ageing treatment, and the hardness reaches over 700 HV after fully precipitated in whole grain. It has been reported so far that the cellular microstructure is formed by discontinuous precipitation, which is also observed in Ni-Cr binary alloys, and the addition of Al enhances the growth rate of the cell. However, the growth mechanism has not been cleared sufficiently. In this study, quantitative results of the microstructure applied on an ordinary cellular boundary diffusion model with thermodynamic equilibrium data to discuss the kinetics of the cellular precipitation growth in Ni-38Cr-Al alloys. Consequently, it was revealed the obtained diffusive activation energy was corresponding to that of Ni-Cr binary alloys, so that the cellular boundary diffusion dominated the cell growth in Ni-38Cr-Al alloys as well as Ni-Cr binary alloys. Meanwhile Al increases the activation energy, Al also increases the amount of Cr in the saturated matrix and pre-exponential factor in the diffusive Arrhenius equation extremely. Therefore Al enhances the growth rate of cellular precipitation in two or three order of magnitude more than those of Ni-Cr binary alloys.抄録全体を表示PDF形式でダウンロード (566K) -
石川 浩一, 清水 哲也, 江幡 貴司, 滝口 常美2006 年 77 巻 2 号 p. 143-152
発行日: 2006/05/31
公開日: 2006/11/30
ジャーナル フリーLead (Pb) is one of the most effective alloying elements to improve the machinability of steels. However the movement of eliminating Pb contents is recently increasing because of reducing environmental impact. Therefore new types of free cutting steels without Pb are strongly required. Ti4C2S2 is one of the promissing candidates of free cutting elements. However the mechanism of improvement in machinability by Ti4C2S2 has not been confirmed yet. In this study we investgated the effect of Ti4C2S2 in 13 % Cr stainless steels. Ti4C2S2 had notch effect like other sulfides such as MnS. Thereby chip breakability was improved. Ti4C2S2 also had tool-protecting effect by forming stable adhesion. On the other hand Ti4C2S2 was not shown remarkable lubricant effect as Pb. The improvement of machinability in 13 mass%Cr ferritic stainless steels by including Ti4C2S2 attribute to the chip breakability and restraint of the tool-wear by forming stable adhesion.抄録全体を表示PDF形式でダウンロード (857K) -
山路 徹, 水間 誠治, 平崎 敏史, 濱田 秀則2006 年 77 巻 2 号 p. 153-161
発行日: 2006/05/31
公開日: 2006/11/30
ジャーナル フリーFor the application to port concrete structures under marine environment, corrosion-resistant property of three types of stainless steel bars (SUS430, SUS304 and SUS316) in concrete was studied by immersing each steel bars in the simulated pore solution in concrete and exposing concrete specimens, in which each steel bars was embedded, under marine environment. Results obtained are as follows. 1. In the sound concrete region without crack, no corrosion was observed in all stainless steels (SUS430, SUS304, SUS316) under high chloride ion content which was around 15 kg/m3 in concrete. Therefore, it can be judged that the chloride threshold level for corrosion of these stainless steels is more than 15 kg/m3. 2. In the cracked concrete region, no corrosion was observed in two types of stainless steel (SUS430 and SUS316). However, very small corrosion was observed in the only crack region on SUS304. This reason is considered to be larger crack width than SUS430 and SUS316. This indicates that some large crack width can not be allowed in case of the stainless steel which has similar corrosion-resistant property to SUS304. It is necessary to study on the maximum allowable crack width. 3. In case that stainless steel bar is applied to port concrete structures under marine environment, the life cycle cost can be lower than the case of carbon steel bar in some specific cases.抄録全体を表示PDF形式でダウンロード (560K)
解説
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土山 聡宏, 高木 節雄2006 年 77 巻 2 号 p. 163-169
発行日: 2006/05/31
公開日: 2006/11/30
ジャーナル フリーSolution nitriding (nitrogen absorption treatment) is one of the techniques to produce high nitrogen stainless steels. In this article, the merits and problems of solution nitriding, the general theory and phenomenon of nitrogen absorption, and the properties of solution-nitrided high nitrogen austenitic steels were reviewed on the basis of the results obtained by authors in the recent research. Especially, the thermodynamics and kinetics of nitrogen absorption were emphasized because of their importance in the production of solution-nitrided materials. In addition, the potential of high nitrogen steels produced by solution nitriding was also briefly discussed in terms of the prospective application of nickel-free stainless steels to fine or micro-sized structural materials for biomedical uses.抄録全体を表示PDF形式でダウンロード (478K)
技術資料
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成田 修二, 濱野 修次, 清水 哲也2006 年 77 巻 2 号 p. 171-178
発行日: 2006/05/31
公開日: 2006/11/30
ジャーナル フリーNitrogen is one of the most effective elements to enhance strength, corrosion resistance and austenite stability of stainless steels. Recently many studies have been conducted about high nitrogen stainless steels produced by pressurized melting process such as pressurized electro-slag-remelting, pressurized induction melting and so on. In this report, mechanical properties and corrosion resistance of an experimental high nitrogen austenitic stainless steel Fe-8Mn-21Cr-4Mo-1.2N ; mass%, produced by a pressurized induction melting method were investigated and the following results were obtained. The tensile strength of the solution treated steel at room temperature is higher than that of SUS304 and the ductility is close to that of SUS304. The 70 % cold worked steel has extreamly high tensile sterength over 2500 MPa maintaining non-magnetic property. The pitting resistance and crevice corrosion resistance are superior to those of duplex stainless steel SUS329J3L and close to an austenitic super stainless steel SUS836L.抄録全体を表示PDF形式でダウンロード (488K)
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