巻号一覧
75 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, 古賀 猛, 清水 哲也, 桂井 隆, 西山 忠夫2004 年 75 巻 2 号 p. 77-84
発行日: 2004/04/15
公開日: 2010/04/09
ジャーナル フリーNitrogen is one of the most effective elements for improving not only strength but also corrosion resistance of stainless steels. As many researchers also have indicated the advantage of nitrogen for high temperature application as well as corrosion properties, the recently developed corrosion resistant austenitic stainless steel, DSN9, which contains 0.5mass% nitrogen and can be produced through the conventional arc furnace process, is one of the most attractive candidates for heat resistant alloys. In this report, mechanical properties of DSN9 at elevated temperature are evaluated and discussed.
DSN9 of solid solution has a higher tensile strength at elevated temperature than heat resistant steel SUS310S and also has almost the same creep rupture strength as heat resistant steel SUH660. After cold working of 60% reduction, DSN9 has a higher strength at elevated temperature than SUH660. The cold working over 60% reduction leads to a high hardness of Hv450 due to work hardening, and the aging at 723K to 823K also leads to a higher hardness of Hv540 due to strain aging of nitrogen or precipitation hardening of Cr2N. Furthermore, it maintains a hardness of Hv500 after aging up to 873K which was higher by 200K compared to conventional cold worked SUS301 for gaskets. This enables excellent seal performance even in high-temperature environments of 673K and above, which was problematic for conventional gasket materials.抄録全体を表示PDF形式でダウンロード (689K) -
植田 茂紀, 野田 俊治, 澤田 義行, 野口 学, 松岡 慶2004 年 75 巻 2 号 p. 85-96
発行日: 2004/04/15
公開日: 2010/04/09
ジャーナル フリーNi-Cr-W-C cast alloy has been expected as the candidate material for high temperature air heater tube in gasification and ash melting system due to good corrosion resistance and high temperature strength. However the corrosion resistance of the conventional alloy had not been sufficient yet because of accelerative corrosion of cyclic oxidation and chlorination around 1173K.
In this work, to increase the heater tube life by enhancing the high temperature corrosion resistance, effects of Al and Si addition on the corrosion in air and N2-10%O2-1000ppmHCl gas was investigated and the following results were obtained.
(1) Al addition was most efficient to enhance the resistance of the gas corrosion due to inhibition of the cyclic oxidation and chlorination by AlCl3 formation and vaporization and by Al2O3 protect layer. But Al addition induced internal AlN formation over 1373K.
(2) Although effect of only Si addition on the enhancement of high temperature corrosion was little, in case of combined addition with Al, Si was efficient to enhance gas corrosion moreover and inhibition the AlN formation. However, Si induced decrease of oxidation scale adherence and matrix ductility.
Furthermore, since carbide and the neighborhood were preferentially attacked by gas corrosion, effects of Cr and W, which were composition of carbide, were investigated. It was found that Cr was effective but excess addition induced decrease of gas corrosion resistance because of α-Cr precipitation. On the other hand, W was effective to alkaline fused salt corrosion, but not to gas corrosion.
On the basis of the above results and for consideration of manufacturable properties, Ni-27Cr-10W-2Al-2Si-0.3C has been developed as high temperature air heater tube material. The developed alloy is superior in high temperature corrosion resistance to conventional alloys and is expected to contribute for increasing the heater tube life.抄録全体を表示PDF形式でダウンロード (3509K) -
高畑 紀孝, 植田 茂紀, 清水 哲也2004 年 75 巻 2 号 p. 97-105
発行日: 2004/04/15
公開日: 2010/04/09
ジャーナル フリーIt is known that Ni-40Cr-4Al (mass%) alloy and Ni-38Cr-3.8Al alloy possess high hardness in aging condition by precipitating α-chromium and γ’ (Ni3Al). So far the alloys have so poor hot workability that the alloys have been investigated in the condition of as-cast coarse grain structure. Recently we succeeded in hot working of the alloys by optimizing chemical compositions and heating temperature and could obtain the finer grain alloys.
In this study the influence of solution treatment and aging on the microstructure and hardness of two kinds of hot rolled Ni-Cr-Al alloys with fine grain structure was investigated, which were Ni-38Cr-3.8Al and Ni-38Cr-4.2Al.
Both alloys maintained fine grain of austenite phase in solution treatment condition with some of spheroidzing α-chromium and the hardness was under 200HV. However, by dissolving almost all of α-chromium phase, the austenite grain drastically coarsened. In case that the cooling rate after soluntion treatment was slow, the hardness was getting high by precipitating α-chromium and γ’ phase in the grain boundary. In the aging condition, fine grain structure has faster precipitating rate than coarse grain structure because of increasing precipitation site in grain boundary. The peak aging hardness of Ni-38Cr-4.2Al alloy was higher than that of Ni-38Cr-3.8Al alloy. That was due to increasing the amount of α-chromium and γ’ phase.抄録全体を表示PDF形式でダウンロード (1033K)
解説
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池田 勝彦2004 年 75 巻 2 号 p. 107-112
発行日: 2004/04/15
公開日: 2010/04/09
ジャーナル フリーIn some advanced countries, especially Japan, the ratio of elder above 65 years old to total population is rapidly increasing. It is important to develop high performance welfare goods. Therefore it is also important to develop new materials for the high performance welfare goods.
Titanium and its alloys are one of very attractive metallic materials for health-care and welfare goods, because these alloys have high specific strength and high biocompatibility. However, high cost of Ti alloys is disadvantage in application to the health-care and welfare goods. To overcome high cost barrier of Ti alloys, Ti-4.3Fe-7.1Cr- and -3.0Al alloys were developed. These alloys have good tensile properties, i.e. about 1GPa as tensile strength, about 20% as elongation and about 50% as reduction in area, in solution treated state.抄録全体を表示PDF形式でダウンロード (90K) -
及川 勝成, 光井 啓, 石田 清仁2004 年 75 巻 2 号 p. 113-120
発行日: 2004/04/15
公開日: 2010/04/09
ジャーナル フリーPhase equilibria and microstructure control of sulfide in steel have been reviewed and discussed. The configuration of phase equilibria of metal- sulfide pseudo binary systems can be classified into four types based on invariant reactions and melting points of metal and sulfide. M1type:The monotectic reaction with two-liquid separation is present where the melting point of sulfide is lower than that of metal. M2 type:The two-liquid phase separation is present where the melting point of sulfide is higher than that of metal. E1 type:The eutectic reaction is present where the melting point of sulfide is lower than that of metal. E2 type:The eutectic reaction is present where the melting point of sulfide is lower than that of metal. The phase diagram of many metal-sulfide system shows misbility gap in liquid phase which is quite different with that of metal-carbide and metal-nitride systems.
Typical microstructure of sulfides in steel is shown and the reiaion between the morphology of sulfide and the phase diagram is discussed. In addition, typical examples of the phase diagram application to the microstructure control of sulfides in steel are presented. The phase diagrams are expected to be useful for design of new sulfide dispersed steel.抄録全体を表示PDF形式でダウンロード (353K)
技術資料
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古瀬 泰輔, 佐久間 仁, 平川 裕一, 角屋 好邦2004 年 75 巻 2 号 p. 121-126
発行日: 2004/04/15
公開日: 2010/04/09
ジャーナル フリー12Cr heat-resistant steels have been previously used for high-temperature bolts for steam turbines. Currently, the maximum steam temperature in steam turbines has been raised to around 873K, in order to improve thermal efficiency. Consequently, austenitic alloys must be used to accommodate these more severe conditions (at steam intakes, for example), as 12Cr steel loses creep strength under such conditions. However, although austenitic alloys such as Refractaloy 26 possess higher creep strength at high temperatures, such alloys have the disadvantage of greater thermal expansion and higher cost compared to 12Cr heat-resistant steel. Therefore, it became necessary to develop 12Cr steel with higher creep strength to replace austenitic alloys in applications involving advanced 903K-class steam turbines.
12Cr steel with higher creep strength, containing 3% Co, 0.7% Mo, and 1.8% W, had already been developed for rotor forgings. In this study, quench-hardening and ingot-soaking temperatures were investigated. Based on the results of this investigation, creep strength and absorbed energy were improved compared to conventional bolt materials.
In commercial lot production, the VIM-VSR re-melting process was applied to reduce segregation of chemical compositions, variation of boron yield, and non-metallic inclusion in the ingot. Furthermore, precise control of the forging temperature of the rotary forging machine prevented precipitation of delta ferrite. Accordingly, 12Cr steel with high creep strength was successfully manufactured for use in high-temperature bolts and rotor blades.抄録全体を表示PDF形式でダウンロード (390K) -
鈴木 昭弘, 小川 道治, 清水 哲也2004 年 75 巻 2 号 p. 127-131
発行日: 2004/04/15
公開日: 2010/04/09
ジャーナル フリーTitanium alloys, high strength and low density materials as compared with steels, have been popularly used for golf club heads of drivers and fairway woods. The advantage of titanium alloys is to realize an oversized club head with a large sweet spot without increasing overall weight of a golf club. So far great effort has been made to produce the oversized golf club head. However, the larger the club head become, the thinner the wall of the club head is required. In order to make the wall thin further, the development of a new titanium alloy that has higher strength and toughness than conventional alloys is necessary.
In this study, to develop a new beta-titanium alloy for the golf club heads, optimization of chemical composition of a Ti-V-Cr-Al alloy system was carried out based on a conventional beta titanium alloy Ti-22V-4Al. Chromium, one of the solid solution strengthening elements of the beta phase, was employed to enhance the strength of alloys. Vanadium content was optimized to obtain good ductility and to control age hardening speed.
After the solution and aging treatment, one of the designed alloys, Ti-15V-6Cr-4Al, showed excellent combination of strength and toughness as compared with conventional beta alloy Ti-22V-4Al. Further, the combination between tensile strength and ductility of this alloy was improved by cold working and age-hardening.
The performance test of golf club heads fabricated by this developed alloy Ti-15V-6Cr-4Al revealed good durability as compared with conventional alloy heads made by Ti-22V-4Al and Ti-15V-3Al-3Cr-3Sn.抄録全体を表示PDF形式でダウンロード (217K) -
植益 広, 竹中 雅志, 清水 哲也, 阿部 正美, 平崎 敏史, 濱田 秀則2004 年 75 巻 2 号 p. 133-138
発行日: 2004/04/15
公開日: 2010/04/09
ジャーナル フリーCorrosion tests of 10 kinds of stainless steels have been conducted for 5 years under three conditions of marine environments, which are atmospheric corrosion, intermittent seawater spray and intermittent seawater immersion.
Rating number increased with PRE(Cr+3.3Mo+16N;mass%) value in all test conditions and the stainless steels of which the value were over 37 showed excellent corrosion resistance under marine environments.
Maximum pit depth decreased with increasing PRE value in all test conditions.
Rating number settled after a couple of months from the start and then the number almost unchanged. On the contrary maximum pit depth grew with increasing test duration. It is suggested that the progress of corrosion mainly depened on the pit growth.抄録全体を表示PDF形式でダウンロード (423K)
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