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79 巻, 6 号
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森 忠洲1993 年 79 巻 6 号 p. 619-627
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーPDF形式でダウンロード (1399K) -
松村 泰治, 船橋 佳子, 広川 吉之助, 石黒 三岐雄, 黒澤 文夫, 薦田 光徳, 日野谷 重晴, 遠藤 丈, 河村 恒夫, 間嶋 エミ ...1993 年 79 巻 6 号 p. 628-637
発行日: 1993/06/01
公開日: 2010/02/16
ジャーナル フリー以上の共同実験結果よりステンレス鋼および高Crフェライト鋼中析出物の抽出分離定量法(推奨法)をまとめ,表9に示した。結果を要約すると以下のとおりである。
(1)ステンレス鋼中のTCP相(σ相,χ相)は, 1%HA系電解法により抽出できる。このうちσ相は10%臭素-メタノール溶液に溶解するので,電解抽出残さを10%臭素-メタノール溶液に浸漬処理し,溶解液を分析すれば,σ相組成が求められる。
(2)ステンレス鋼中の炭化物は, 1%HCl系あるいは10%AA系電解法により抽出できる。
(3)高Crフェライト鋼中のTCP相(Laves相)と炭化物は,10%AA系電解法により抽出できる。Laves相は, 0.5%臭素-メタノール溶液に溶解するので,電解抽出残さを0.5%臭素-メタノール溶液に浸漬処理し,溶解液を分析すれば,Laves相組成が求められる。抄録全体を表示PDF形式でダウンロード (8329K) -
武田 紘一, 日比 政昭, 竹内 英麿, 坪井 晴己, 森寺 弘充, 田中 和夫1993 年 79 巻 6 号 p. 638-644
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーThe feasibility of the use of a plasma jet was studied for the ignition of pulverized coal combustion and suppression of nitrogen oxide formation. The analyses of the product gases under various experimental conditions led to the following results:
(1) By the assistance of plasma injection, pulverized coal can be ignited without any addition of auxiliary oil or gas. The proportion of plasma energy necessary to maintain stable combustion does not exceed several percentages of heat input of the coal.
(2) Suppression of nitrogen oxide formation can be expected even in the range of high combustion efficiency, if the plasma assisted burner is appropriately designed. Nitrogen plasma plays an important roll to reduce the nitrogen oxide.抄録全体を表示PDF形式でダウンロード (1237K) -
平田 武行, 石川 稔, 姉崎 正治, 丸川 雄浄1993 年 79 巻 6 号 p. 645-651
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーFor the examination of stirring effect in the in-bath smelting reduction process, influence of stirring on the reduction rate of chrome ore was studied. The experiments were mainly carried out using a ten-ton test converter with oxygen top-blowing, nitrogen side-blowing and nitrogen bottom-blowing. After five tons of chrome ore were fed with coke and lime on five tons of molten iron, the stirring effect was examined by changing the gas blowing conditions.
Main conclusions are as follows:
(1) The change in the reduction rate caused by the change in the blowing conditions corresponds with the change in the stirring power for the slag layer.
(2) The nitrogen side-blowing has nearly the same effect on the slag stirring as the nitrogen bottom-blowing has, when the blowing rate is the same.
(3) The nitrogen side-blowing is suitable for the intensive stirring of slag, which contributes to enhancing the reduction rate of chrome ore.抄録全体を表示PDF形式でダウンロード (1129K) -
片山 博, 宮内 克行, 出倉 直樹, 桃野 正, 平井 伸治1993 年 79 巻 6 号 p. 652-658
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーChromite ores prereduced to various stages of reduction were reduced by carbon at 1550 and 1600°C in the presence of molten slag of CaO-MgO-Al2O3-SiO2 system.
Chromium became liable to dissolve in the form of Cr2+ rather than Cr3+ in slag during the smelting reduction of chromite ores prereduced at 1200°C or above, even when the ores had higher iron content. This seemed to be mainly attributed to the fact that the dissociation oxygen pressure of chromite was decreased by preferential reduction of iron oxide in prereduction stage.
Metal produced in prereduction stage melted and flowed out to liquid droplets in the vicinity of chromite grain during the smelting reduction. As a result, indentations and pores were formed on the surface and inside of chromite grain, respectively.
The rate of smelting reduction increased with increasing the degree of reduction in prereduction stage. This seemed to be attributed to the increases in number and size of the indentations and pores as well as the change of oxidation state of chromium from Cr3+ to Cr2+.抄録全体を表示PDF形式でダウンロード (5543K) -
平野 聡, 安田 健, 児玉 英世, 木村 智明, 福井 克則, 松永 滋1993 年 79 巻 6 号 p. 659-664
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーStrip casting experiments on type 304 stainless steel have been carried out in a steel twin-roll caster with rolls 300 mm in diameter and 80 mm wide. The casting speed was 6.68.0 m/min. Thickness of the strips was about 2.4 mm.
Roll temperature was measured at 1mm deep from outer surface of the roll during casting. Abnormal acceleration behavior of temperature change was detected. The annomalous acceleration of the thermo-electromotive force is caused by reduction in solidified shell thickness during squeezing. Calculation by finite difference method agreed with the result of temperature measurements. Simulation revealed that the heat transfer coefficients are, respectively, 2.54.2 and 1016.7 kW/m2K before and after squeezing.抄録全体を表示PDF形式でダウンロード (3304K) -
鄭 鎭煥, 張 栄遠1993 年 79 巻 6 号 p. 665-670
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーThe deformation and transformation processes of an Fe-0.28%C-1. 41%Si-1.50%Mn steel subjected to various annealing conditions were investigated using in-situ TEM and SEM straining techniques. The retained austenite(γR) was observed in three distinctly different morphological forms, i. e., a film type located between bainite laths, an island type isolated in relatively large ferrite grains, and a granular type located at grain boundaries especially triple junction points. When stress was applied on the steel, the ferrite matrix was found to deform first piling-up dislocations at ferrite-γR boundaries. The internal stress fields generated by these piled-up dislocations seem to act as the driving force for the deformation induced transformation of γR. As the plastic deformation proceeded, fracture began with void formation at ferrite-second phase interfaces leading into subsequent void growth and coalescence until a final failure. The in-situ TEM observation showed that the transformation of γR is accomplished in the two different paths, i. e., γR→twin→α' and γR→α'. The orientation change resulting from a γR→α' transformation can be described by the Kurdjumov-Sachs relationship.抄録全体を表示PDF形式でダウンロード (11291K) -
小野寺 隆二郎, 水井 直光1993 年 79 巻 6 号 p. 671-677
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーEffect of prestrain on the precipitation hardening in 1.4%Cu-added ultra-low carbon Ti-added steel has been studied. The specimens were aged at temperatures below 550°C after annealing or subsequent prestrain up to 10%.
The as-annealed specimens showed considerable precipitation hardening only around 550°C. While the prestrained specimens hardened at a temperature as low as 350°C. The electrical resistivity and hardness measurements revealed that there existed a new nose for Cu aging around 400°C in addition to normal one around 600°C. The former nose can be related to formation of metastable phase, and was largely accelerated by the prestrain. This acceleration effect can be explained in terms of higher diffusivity of Cu atoms due to excess vacancies formed by the prestrain.抄録全体を表示PDF形式でダウンロード (3884K) -
村上 敬宜, 鳥山 寿之, 子安 善郎, 西田 新一1993 年 79 巻 6 号 p. 678-684
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーIt is well known that the fatigue strength of high strength steels are strongly influenced by the existence of nonmetallic inclusions. It is said that the effects of nonmetallic inclusions on the fatigue strength of high strength steels depend on their size, shape, chemical composition and locations where they exist. Therefore, nonmetallic inclusions are likely to cause a large scatter in fatigue strength.
A firm opinion that hard inclusions are more detrimental than soft inclusions for fatigue strength, has prevailed for long years.
In the present paper, this opinion is proved incorrect by detailed investigations of the chemical composition and size of inclusions observed at fracture origin, i. e., the chemical composition of inclusions is not crucial factor controlling fatigue limit, even if the chemical composition influences the rigidity of inclusions and the residual stresses around inclusions.
On the contrary, it is verified that two crucial factors which control the fatigue strength are the Vickers hardness of matrix (HV) and the square root of projection area of inclusion (√area). It is shown that the lower bound of large scatter in fatigue strength can be successfully predicted by the statistics of extreme values (√area max) of inclusions contained in many specimens.抄録全体を表示PDF形式でダウンロード (4228K) -
高井 健一, 関 純一, 崎田 栄一, 高山 康一1993 年 79 巻 6 号 p. 685-691
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーEffects of Si and Ca addition on delayed fracture of medium carbon steels with 1400N/mm2 strength were investigated. Silicon and calcium were added at concentrations of 02.0% and 3070ppm, respectively. The delayed fracture characteristics were evaluated by FIP (Fédération Internationale de la Précontrainte) test which is a constant tensile load test in 20% NH4SCN solution at 323 K. In order to make clear the effect of adding Ca and Si, the fracture surfaces were examined, and the hydrogen evolution behavior, the diffusion coefficient of hydrogen, and the hydrogen content were measured. It was found that 0.5%Si steels have no effect on the time to fracture regardless of Ca content, while 1.5%Si-30ppm Ca steel has the longest time to fracture. Fractography showed that adding Ca to 0.5%Si steels did not change the intergranular fracture area fraction. However, adding Ca to 1.5%Si steels changed the fracture from intergranular fracture to microvoid coalescence fracture. As for hydrogen behavior after three months from FIP test, 0.5%Si steel released hydrogen at the peak of 500 K, while for the 1.5%Si-30ppm Ca steel the peak was at 700 K. It was suggested that hydrogen released at around 500 K was crucial for delayed fracture characteristics.抄録全体を表示PDF形式でダウンロード (6867K) -
中村 峻之, 佐藤 始夫1993 年 79 巻 6 号 p. 692-698
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーThe effects of heating atmosphere on oxidation behaviour at high temperature of steels with various Si content(0.060.4%Si), but constant in other elements, have been investigated. The results obtained are summarized as follows.
Fayalite, Fe2SiO4, formed at the interface of scale/matrix affected the oxidation behaviour. Therefore, solid Fe2SiO4 formed at oxidation temperatures up to 1170°C, which was the eutectic point of Fe2SiO4 and FeO phase, raised heat resistance, but liquid phase of Fe2SiO4 at oxidation temperatures exceeding 1170°C accelerated the oxidation. The change of oxidation behaviour occurred at the Si content between 0.1% and 0.2%. Increasing Si content in steel, Fe2SiO4 formed at the interface of scale/matrix increased gradually. When the whole interface was covered with Fe2SiO4, the oxidation behaviour should be affected by the change of diffusion rate on Fe++ ion from iron matrix to scale. H2O and O2 content in heating atmosphere promoted the oxidation of iron, but the effect of H2O was much more than O2. The mean diameter of pores in scale was in proportion to oxidation weight gain, and therefore Si content and oxidation condition affected on mean diameter of pores in scale through the oxidation weight gain.抄録全体を表示PDF形式でダウンロード (5853K) -
宮原 一哉, 莫 建平, 柴田 昭, 細井 祐三1993 年 79 巻 6 号 p. 699-705
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーSKD11 tool steel is one of the steels which contain high compositions of carbon and alloying elements forming a lots of carbides. Major part of these carbides are coarse eutectic carbides which are difficult to be refined through the conventional heat treatment. In order to obtain the refinement of the carbides and the improvement of deformability of SKD11 steel, powder metallurgy method (P/M) of HIP treatment of atomized powder followed by hot forging was utilized and the characteristics of high temperature deformation behaviors of the P/M SKD11 materials and also the effects of the powder particle size and HIP treatment condition were investigated. Maximum elongation of 196% was obtained at the lowest strain rate of 5.6×10-5s-1 in this work and at the test temperature of 1O53K just below Ac1 transformation point. HIP temperature and particle size had generally very small effects on such high temperature deformation behavior. Microstructural observation showed the grain growth and directionality along tensile direction during the deformation at lower strain rates and the test temperature just below Ac1 point. This is cosidered to indicate that the so called "superplasticity due to grain boundary sliding" is not the principal deformation mechanism for the large elongation of the P/M SKD11 steel of the present result.抄録全体を表示PDF形式でダウンロード (7309K) -
阿部 征三郎, 金子 道郎, 水沼 武久1993 年 79 巻 6 号 p. 706-712
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーIntergranular corrosion (IGC) in stainless steels can be well explained by following two mechanisms; "Composition dependent IGC" and "Compound dependent IGC". In this paper, the composition dependent IGC mechanism was discussed. In this mechanism, it has been confirmed that IGC was induced only by the difference of corrosion rates at grainboundaries (GB) and the matrix, due to the change of the chemical composition of GB from that of the matrix.
The high concentration of P due to the GB segregation causes very severe IGC at active state corrosion potentials as in H2SO4 solution, where the Cr depleted zone never induces IGC. The Cr depleted zone is responsible for IGC in the passive state corrosion potential region as in most of standardized IGC test solutions, where only the high concentration of P at GB is not responsible for IGC.
In the next paper, the compound dependent IGC mechanism will be presented.抄録全体を表示PDF形式でダウンロード (10600K) -
阿部 征三郎, 金子 道郎, 小松 肇, 黒沢 文夫1993 年 79 巻 6 号 p. 713-720
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーFollowing the first paper on the study of the composition dependent intergranular corrosion (IGC) mechanism of stainless steels (SS), the compound dependent IGC mechanism has been studied in this paper. In this mechanism, IGC is induced by the dissolution of grain boundary (GB) precipitates of themselves.
It was confirmed that the IGC mechanism played an important role mainly in the transpassive state corrosion potential region above about 1.2V(SHE), where neither the Cr depleted zone nor the segregation of P at GB induced IGC. The film-like and amorphous Ni-P compound, [Ni (Fe, Cr)]3P2 was found to precipitate at GB in Type 304 SS and to cause very thin but very deep IGC. Also, intermetallic compounds of Laves and χ phases were identified to precipitate at GB and to induce severe IGC due to the dissolution of themselves in Type 316 SS.抄録全体を表示PDF形式でダウンロード (10841K) -
柴田 俊夫, 春名 匠, 沖 孝広1993 年 79 巻 6 号 p. 721-725
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーNaF水溶液中における鋭敏化304鋼の応力腐食割れを詳細に検討するために,SSRT中に試料に発生するき裂の成長過程をCCDカメラを用いて連続的に観察し,次に示す結果を得た。
(1)き裂発生時間はWeibull分布に従い,その最小値もしくは平均値は103ppm NaFにおいて最小値を示した。また,き裂発生数は同濃度において最大値を示した。
(2)K'ISCCはWeibull分布に従い,その平均値はNaF濃度の減少とともに低下したが,実際に重要なK'ISCCの最小値は,NaF濃度にほとんど依存しないことがわかった。
(3)き裂進展速度はGumbel分布に従い,その平均値もしくは最大値は103ppm NaFにおいて最小値を示した。
(4)SSRTによって評価されるSCC感受性因子として従来用いられる最大応力は103ppm NaFにおいて最低値を示したが,この因子を支配するのはK'ISCCやき裂進展速度ではなくき裂発生数およびき裂発生時間であることが明確となった。抄録全体を表示PDF形式でダウンロード (3005K) -
柴田 俊夫, 春名 匠, 沖 孝広1993 年 79 巻 6 号 p. 726-731
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーThe effects of temperature and applied potential on the intergranular stress corrosion cracking, IGSCC, susceptibility of sensitized SUS304 stainless steel in NaF aqueous solution have been investigated by using slow strain rate test, SSRT, based on the direct observation of crack generation and propagation during the test. It was found that the decrease in the maximum stress, which is usually used as a conventional SCC susceptibility index by SSRT, with increasing temperature was caused not only by the decrease in K'ISCC and crack generation time but also by the increase in crack growth rate and the number of cracks. The result of potential-controlled SSRT proved that the lowest maximum stress at 100 mVAg/AgCl was induced by the decrease in K'ISCC and crack generation time. In conclusion, crack generation is more important compared with crack propagation for deciding the IGSCC susceptibility of sensitized SUS304 stainless steel in NaF solution.抄録全体を表示PDF形式でダウンロード (963K) -
田淵 正明, 久保 清, 八木 晃一1993 年 79 巻 6 号 p. 732-738
発行日: 1993/06/01
公開日: 2010/02/16
ジャーナル フリーIn order to investigate the relationship between microscopical creep fracture mechanism and creep crack growth rate, creep crack growth tests were conducted on CT specimens of NCF800H alloy. Wedge-type intergranular fracture, transgranular one and cavity-type intergranular one were observed at 873K, 923K and 973K, and 1073K, respectively. For an equal value of C* parameter, creep crack growth rate was the fastest under wedge-type fracture condition, and secondary under cavity-type fracture condition and the slowest under transgranular fracture. Similar dependence of crack growth rate on fracture mode had been observed in creep crack propagation of a SUS316 steel. This corresponds with the difference of creep fracture ductility. Under the cavity-type fracture condition, creep crack growth rate increased as the damaged zone ahead of the crack tip increased. This effect could be explained by Riedel's crack growth model based on the grain boundary cavitation. Therefore, it is necessary to take the effect of creep damaged zone into account, when we evaluate the creep crack growth rate of structural components used for long time at high temperature.抄録全体を表示PDF形式でダウンロード (6925K) -
片瀬 伝治1993 年 79 巻 6 号 p. N397-N404
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーPDF形式でダウンロード (8226K) -
三塚 正志1993 年 79 巻 6 号 p. N405-N416
発行日: 1993/06/01
公開日: 2009/06/30
ジャーナル フリーPDF形式でダウンロード (2334K)
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