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69 巻, 8 号
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奥田 直樹1983 年 69 巻 8 号 p. 887-894
発行日: 1983/06/01
公開日: 2009/06/30
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市山 正1983 年 69 巻 8 号 p. 895-902
発行日: 1983/06/01
公開日: 2009/06/30
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稲葉 晋一, 佐々木 稔, 木原 諄二, 森田 善一郎1983 年 69 巻 8 号 p. 902-902,912
発行日: 1983/06/01
公開日: 2009/06/30
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松山 晋作1983 年 69 巻 8 号 p. 903-912
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリー実橋における高力ボルトの遅れ破壊に関する事例解析結果をまとめると次のようになる.
1) 橋梁の桁構造別にみると箱桁における損傷例が多かつた.これは桁内部に水が溜まるために日照時には高温高湿条件となり腐食反応が生じやすいためである.したがつて,箱桁には水抜き孔を設けて桁内部が乾燥状態を保つようにすることが破損防止上必要である.
2) 橋梁によつて破損が上フランジ,ウェブ,下フランジなどのある箇所に集中する傾向が認められた.この原因は明らかではないが,ボルトの遊びねじ長さ,水滴の溜まりやすさ,温度上昇度など,ボルトの製造ロット別に生ずる材質的差異以外の要因が考えられる.
3) ボルトの破断部位は不完全ねじ部が一般的には多いが,橋梁によつては首下破断が多発する場合もあつた.規格上は首下はねじ部より強い筈であるから,首下破断を生ずる理由には,第一に頭が下向きの場合首下に水滴が溜まりやすいこと,第二に首下の丸み部に座金の角があたり荷重が集中したことが考えられる.とくに後者の場合には座金が遅れ破壊してボルト孔内部への水の浸入を容易にすることもある10)ので,座金の内側隅は十分面とりする必要がある.
4) F 13T (No.4)を適用した唯一の橋梁で約15年間にわたりボルトの破損傾向を追跡調査した.その結果ボルト破損の確率分布は二母数ワイブル分布に従うことが認められた.継手のすべりに対する安全率を考えると,破損の補修をしなかつた場合にはこの橋梁は約40年で変状を生ずると推定された.
5) F 11Tを使用した橋梁で最初の破損を生ずるまでの寿命分布も二母数ワイブル分布で表され,故障率が時間と共に低下する傾向を示した。現在F 11Tの使用は中止されているから,すでにF 11Tを使用している既設の橋梁での遅れ破壊事例は今後減少傾向にあると推定される.
6) 高力ボルトを適用した初期の橋梁や遅れ破壊を発生した橋梁についてボルトを採取して軸部の鉄さびの分析を行つた.直接雨に曝された箇所や箱桁ではボルトが湿つた状態にあるものが多かつたが,鉄さびの組成からも水の存在が認められた.遅れ破壊は水の存在下で腐食反応の結果生ずる水素により誘起されるもので,乾燥状態で使用されていれば遅れ破壊は生じない.
7) 破面の破壊起点部には旧オーステナイト粒界割れがみられた.材料によつては破壊途中で圧延方向にミクロ偏析帯に沿つて粒界割れを生ずる縦割れが認められた.
8) 遅れ破壊を生じたボルトの最小硬さはHRC 37.5であつた.従来の実験から得られた遅れ破壊を生ずる限界硬さはHRC 41であるから,HRC<41で破損したボルトは材質的鋭敏化原因があつたと考えられる.その原因として,浸炭による表面硬化, Pの粒界偏析, Bの粒界における存在などが考えられた.これらの原因の検討から,熱処理炉の雰囲気は脱炭傾向にすること,可能な限り低燐の高純度鋼を用いること, B添加は必要最少量にすることなどが高力ボルトの信頼度を高めるために必要であると結論される.しかし市販鋼では高純化には限度があるから粒界炭化物が十分凝集するまで焼もどし温度を高めることが必要である.
9) 一般に炭素量が多いと焼もどし軟化曲線の勾配が急になり,焼もどし温度変化の硬さへの影響が大きくなるから,炭素量の多い鋼種で高強度化するのは望ましいことではない.またバッチ型焼もどし炉のように装入方法によつては温度むらを生ずる場合には,一部に焼もどしが不十分で硬さの高い製品が混入する可能性があるので注意が必要である.抄録全体を表示PDF形式でダウンロード (7340K) -
石井 不二夫, 井口 泰孝, 萬谷 志郎1983 年 69 巻 8 号 p. 913-920
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーThe solubility of nitrogen in liquid chromium and chromium-iron alloys has been studied by a sampling method at the temperatures of 1550°1780°C and under 0.041.0 atm of nitrogen.
The free energy of solution and the activity of nitrogen in liquid chromium and chromium-iron alloys were determined by applying the interstitial model for the experimental results.
The results obtained are summerized as follows:
(1) Nitrogen dissolved in liquid chromium and chromium-iron alloys upto 50% Fe does not obey Henry's law, and solubility of nitrogen in liquid chromium is given by the following equation.
log K(Z)=5515/T-3.193, K(Z)=aN/√PN2=ψNZN/√PN2
(2) Activity coefficients of nitrogen based on pure liquid chromium are expressed as follows :
log ψNN(cr)=(4235/T-1.513)·YN YN<0.21
log ψFeN(cr)=1.80·YFe YFe<0.7
(3) Activity coefficients of nitrogen in iron-chromium alloys based on pure liquid iron are shown by the following equations :
log γcrN(Fe)=(-13765/T+3.10)·XCr Xcr<0.16
log fcrN(Fe)=(-148/T+0.033)·[%Cr] [%Cr]<15
Where YN and ZN are the mole ratio and the lattice ratio of nitrogen in liquid metal respectively.抄録全体を表示PDF形式でダウンロード (1143K) -
萬谷 志郎, 丸山 信俊, 藤野 伸司1983 年 69 巻 8 号 p. 921-928
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーThe vapor pressure of P on liquid Fe-P-j (j= C, Si, Al, or B) alloys has been measured by the transportation method at 1673 K.
The results obtained were treated by the model of interstitial solution proposed by J. CHIPMAN, and the effect of alloying elements on the activity coefficient of P in liquid iron was determined by assuming C and B as interstitial elements and Si and Al as substitutional ones respectively.
The interaction parameters are summarized as follows:
εCP=(∂1nγP/∂Xc)XFe→1=5.43±0.67
εSlP=(∂1nγP/∂Xsi)XFe→1=7.68±0.44
εAlP=(∂1nγP/∂XAl)XFe→1=3.57±0.33
εBP=(∂1nγP/∂XB)XFe→1=1.49±0.16抄録全体を表示PDF形式でダウンロード (924K) -
松尾 輝夫, 横大路 照男, 吉田 誠, 山本 里見, 川村 和郎1983 年 69 巻 8 号 p. 929-936
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーChemical reactions for the recovery of Na2CO3 from the slag obtained in the refining of hot metal with Na2CO3 were studied. The process for the Na2CO3 recovery consisted of three main unit operations.
1) Dissolving of the slag in the circulating aqueous solution.
2) Removal of residue and impurities (Si, P) from the solution.
3) Recovery of Na2CO3 from the solution.
More than 90% of Na, P, V and 40 to 50% of S, Si contained in the slag dissolved in the solution and main ion species in the solution were proved as Na+, V5+, OH-, CO2-3, SiO2-3, PO3-4, S2-, S2O2-3and SO2-4. With the addition of CO2, OH-/CO2-3 ratio in the solution turned to nil and Si concentration in the solution reduced to 2g/l because of hydrolysis of SiO2-3 ion. Addition of Ca(OH)2 in the solution caused reduction of P concentration to less than 3g/l, due to the formation of Ca3(PO4)2·Removal of V and S ion were also studied. From these experiments, a process-flow for the Na2CO3 recovery from the slag was proposed.抄録全体を表示PDF形式でダウンロード (1569K) -
松尾 輝夫, 横大路 照男, 吉田 誠, 山本 誠二, 山本 里見, 福田 昭一1983 年 69 巻 8 号 p. 937-943
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーRecovery of Na2CO3 from the sodium containing slag was studied. The experimental plant process consisted of several unit operations, such as dissolving of the slag in the aqueous solution, removal of Si and P from the solution, separation of the precipitate and the residue from the solution, crystallizing of Na2CO3 hydrate from the solution and drying the Na2CO3 hydrate. The plant could process the slag and produce Na2CO3 at the rate of 120 kg/h and80 kg/h, respectively. The slag obtained in the continuous refining of hot metal with Na2CO3 was used as the raw material. By examining for more than ten days, the following results were obtained. 1) Small particles (1.3mm dia.) of Na2CO3were obtained and the yield was 82.5%. The contents of impurites (P, Si, and S) in the recovered Na2CO3 were lower than the ranges which were unfavarable for the refining of hot metal. 2) The plant was operated without difficulties and treatment of the byproducts such as insoluble material and precipitate of dephosphorization presented no problem.抄録全体を表示PDF形式でダウンロード (1076K) -
檀 武弘, 郡司 好喜1983 年 69 巻 8 号 p. 944-950
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーThe purpose of this investigation is to study the variation of total oxygen content in molten iron deoxidized by Ti, and Ti-Si, Ti-Mn and Ti-Si-Mn alloys as well as to observe the morphology of the deoxidation products.
The results obtained are summarized as follows:
(1) Titanium deoxidation: With less than 0.12% Ti addition, molten FeO-TiO2 binary droplets were formed. With more than 0.15% Ti, titanium oxide with high melting point precipitated as deoxidation product. In the latter case the deoxidation rate and limit were satisfactory.
(2) Ti-Si deoxidation: The products have the similar morphology to that in the case (1) but their sizes were considerably larger. The very low Si content in the products was found. The deoxidation rate and limit were slightly worse than those in the titanium deoxidation.
(3) Ti-Mn deoxidation: The products seemed to be liquid complex oxides containing Ti and Mn. They were very large and perfectly spherical. The deoxidation rate and limit were deteriorated.
(4) Ti-Si-Mn deoxidation: The products consisted of titanium, manganese and silicon oxides. Their Si contents were as low as that in the Ti-Si deoxidation. The deoxidation rate and limit were superior to those in the case (3) and inferior to those in the case (2).抄録全体を表示PDF形式でダウンロード (9293K) -
井上 亮, 水渡 英昭1983 年 69 巻 8 号 p. 951-958
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーFrom an experiment that Na2CO3 reacted with solid Fe-54% V alloy at 1100°C, the following equation was derived for the reaction of vanadium oxidation by soda ash.
Na2CO3+ 4/5V= Na2O+ 2/5V2O5+ C
Vanadium valencies in the soda flux (Na2CO3, Na2CO3-FeO) reacting with carbon-saturated iron melt have been examined as a function of time. The V2O5 produced by the above equation was found to gradually reduced by carbon and/or silicon, changing to the valency V5+→V4+→V3+. The reduction rate of vanadium oxide was reduced by the addition of iron oxide.
The oxidation behavior of phosphorus, vanadium, and silicon in carbon-saturated iron melt has been studied by use of soda flux (Na2CO3, Na2CO3-Fe2O3) at 1300°C. The oxidation of phosphorus and vanadium were initially retarded if a small amount of flux was added by installments and after the end of flux addition the reversion of phosphorus and vanadium occurred. In comparison with the results obtained in the addition of soda flux by a lump, the retardation of initial oxidation was explained by the fact that the reversion rate of phosphorus and vanadium was considerably fast. The effect of Fe2O3 addition to the flux was found to be significant in both experiments using a lump and installment additions. The extensive removal of vanadium was observed in the addition of Fe2O3 by installments, while neither dephosphorization reaction nor the vanadium reversion took place. The same oxidation behavior found in the Na2CO3-Fe2O3 flux was obtained in an experiment using the CaO-CaF2-Fe2O3 flux.抄録全体を表示PDF形式でダウンロード (1096K) -
安谷屋 武志, 原 富啓, 福島 久哲, 東 敬1983 年 69 巻 8 号 p. 959-966
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーZn-Fe alloys were electrodeposited on a rotating sylindrical copper electrode from the sulfate bath, and the surface appearance of the alloys were observed. The alloys electrodeposited under certain plating conditions demonstrated a characteristic striated patterns which followed the direction of flow of the solutions. The reason of appearance of this striation was considered on the basis of the anomalous electrodeposition mechanism of Zn-Fe alloys proposed so far by the authors. In addition, several attempts were made in order to diminish the striated pattern.抄録全体を表示PDF形式でダウンロード (8152K) -
塚谷 一郎, 須藤 正俊, 高田 寿1983 年 69 巻 8 号 p. 967-974
発行日: 1983/06/01
公開日: 2010/02/16
ジャーナル フリーThe morphology and distribution of sulfides in steel ingots having different silicon contents from 0 to 2.0% at 0.3 to 1.5% manganese contents were investigated with a directional-solidification technique. The steels had carbon content of 0.05%, sulfur content of 0.05% and low oxygen content and they were solidified at cooling rate of 5°C/min. The deformation behavior of their sulfides during hot-rolling after heating at 800°1200°C was also investigated.
In the specimen containing 0% Si and 0.3% Mn, the manganese sulfides in the as-cast state were globular in shape and contained about 40% FeS (GlObular sulfide is called type It.). Silicon addition above 1.1% changed the morphology of sulfides from type It to type III according to Sims' classification and decreased the FeS content of manganese sulfide. Type II sulfide was observed in the specimens containing manganese in the range of 0.61.5% at 0% Si.
The relative plasticity of sulfides increased as the heating (_??_ rolling) temperature decreased from 1200°C. While with type II in 1.0% Mn steels the trend continued to 800°C, with type It and III in 0.3% Mn steels maximum plasticity was encountered at 1000°C. The decrease in relative plasticity had a close relationship with the increase in the FeS content of manganese sulfides and the decrease in manganese sulfide size. The difference in plasticity between type It and III MnS and type II MnS was thought to be due to presence of FeS.抄録全体を表示PDF形式でダウンロード (6734K) -
小松原 望, 渡辺 征一, 大谷 泰夫1983 年 69 巻 8 号 p. 975-982
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーDirect-quenching after hot rolling above recrystallization temperature in austenite was investigated in low carbon and low alloy high tensile strength steels. Effects of cooling rates during direct-quenching on the microstructures, strength, and toughness were investigated, comparison being made with reheat-quenching.
It was clarified that the strength and toughness were remarkably improved by direct-quenching in a certain range of cooling rates, in which the microstructure of direct-quenching showed up as a mixture of martensite and fine bainite, while that of reheat-quenching was coarse bainitic. These results showed that the improvements of the strength and toughness were due to the enhancement of hardenability by direct-quenching.
By calculating ideal critical diameters from tensile strengths of as-quenched steel plates, it became clear that the increase in hardenability by diect-quenching was about by 40%. It was too large to ascribe the increase of hardenability only to the difference of austenite grain sizes in direct-quenching and reheat-quenching.
Some possible mechanisms for these interesting phenomena were discussed.抄録全体を表示PDF形式でダウンロード (3451K) -
宗木 政一, 河部 義邦, 高橋 順次1983 年 69 巻 8 号 p. 983-989
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーWhen the conventional thermomechanical treatment (TMT) was applied to the 10Ni-18Co-14Mo maraging steel, the austenite grain was refined to below l0μ but the precipitation in austenite could not be suppressed, thus resulting in the rather lower strength. This study has been conducted to achieve the nominal 350kgf/mm2 tensile strength by optimizing the thermomechanical processing variables and by modifying the chemical composition of the steel. In order to obtain the microstructure with fine grain and no coarse precipitates formed in austenite, the special thermomechanical treatment (STMT) has been developed. STMT consisted of multipass rolling from the solution treatment temperature to 1000°C, interrupting the rolling and air cooling to the temperature which is below the nose temperature of precipitation start curve and just above the recrystallization temperature, re-rolling quickly by sufficient amount of reduction, and quenching below room temperature. This interrupted rolling is essential to suppress the strain-induced precipitation. When STMT was applied to two steels, the nominal microstructure was not obtained for the 10Ni-18Co-14Mo steel but was successfully obtained for the 10Ni-18Co-12Mo-1Ti steel. It is, however, essential to choice the correct re-rolling temperature and to employ the adequate amount of reduction, and by optimizing these rolling conditions, the tensile strength of 363kgf/mm2 was achieved in the 10Ni-18Co-12Mo-1Ti maraging steel.抄録全体を表示PDF形式でダウンロード (6552K) -
藤田 充苗, 河部 義邦, 入江 宏定, 塚本 進1983 年 69 巻 8 号 p. 990-997
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーThe influence of the electron beam welding condition on the strength of welded joint in maraging steel sheets having strength level of 250kgf/mm2 has been studied. The influence has been discussed on the basis of the variation of the welding heat input and the width of weld metal under various welding conditions.
The strength of heat affected zone is equal to that of the base metal.The strength of weld metal is lower than that of the base metal and is not affected by the welding heat input. Therefore, the joint is such that the weld metal of lower strength is inserted between the base metal having higher strength.
The strength of the welded joint decreases gradually with the increase in the welding heat input. The plastic deformation of the weldment concentrates in the weld metal and in tensile test specimens fail there. On the other hand, the width of weld metal becomes wider with the increase in the welding heat input. Thus, the dependence of the strength of the welded joint on heat input can be explained by the fact that the plastic constraint of the base metal for the weld metal decreases with the increase in the width of the weld metal.抄録全体を表示PDF形式でダウンロード (4695K) -
星野 和夫1983 年 69 巻 8 号 p. 998-1005
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーThe flow stress (σ) of unstable austenitic stainless steels is studied by comparing stable austenitic and martensitic stainless steels.
(1) The root of dislocation density (√ρ) obtained by X-ray analysis in stable γ-phase increases with strain (ε) and the expression of ε as a function of √ρ is parabolic.√ρ of γ phase mixed with deformation-induced martensite (α') increases with the root of α'phase volume fraction (Vα'1/2) in addition to the above relation.
(2) σ of unstable steels is intermediate of the values caluculated by "equal stress model" and"equal strain model" and it becomes to take the values estimated by equal strain model with increase of α'-phase.In this case, the higher the strength of α' phase is and the larger the volume of α' phase is, the higher is the ununiformity of strain between γ and γ' phase. In the case that the strength of α' phase is almost the same, the smaller the volume of γ' phase is, the smaller is the ununiformity of strain between γ and α' phase.
(3) σ is affected not only by the volume but also by the strength of α' phase and inversely plastic flow depresses α'-transformation to inhibit the enhancement of higher σ values due to high strength of α'-phase.抄録全体を表示PDF形式でダウンロード (1386K) -
坂井 義和, 田辺 龍彦, 鈴木 正, 吉田 平太郎1983 年 69 巻 8 号 p. 1006-1013
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーCorrosion tests of Inconel 617 were carried out in a temperature range from 900°C to 1040°C in helium environment with small amounts of impurity gases, which was the simulated primary coolant of High Temperature Gas cooled Reactor (HTGR), and the carburization, decarburization, and oxidation were investigated in terms of temperature.
(1) The alloy was carburized in the temperature range from 900°C to 970°C, but was decarburized above 990°C. The transition temperature from carburization to decarburization was estimated to be 975°C. In the temperature range, where carburization occurred, the largest carbon pickup was observed at 940°C, however, in the temperature range of decarburization, the degree of decarburization increased with the increase of temperature.
(2) In the temperature range of carburization, the carburized layer was observed at near-surface region, and Cr-Mo carbides precipitated along the grain boundaries and twin boundaries. In the temperature range of decarburization, the carbides along the grain boundaries disappeared, and this led to the formation of altered layer, the depth of the layer reaching to about 2000μ after 500h corrosion at 1040°C.
(3) In contrast to the results that the oxide films formed at high temperature in air were dense and protective, the films formed in the helium environment were very porous and less protective. Further, the chromium content in the oxide films along the grain boundaries beneath the surface decreased with the increase of test temperature. This could lead to make the films much less protective.抄録全体を表示PDF形式でダウンロード (8940K) -
近崎 充夫, 添野 浩, 福井 寛, 大高 清1983 年 69 巻 8 号 p. 1014-1021
発行日: 1983/06/01
公開日: 2010/02/16
ジャーナル フリーPack cementation process has been applied for aluminide and platinum-aluminide coating on a nickel-base superalloy IN-738LC. Burner rig test using light oil containing 0.33%S was carried out for the evaluation of hot corrosion resistance.
Aluminide coatings have two coating layers. The outer layer is high-Al NiAl and the inner layer consists mainly of low-Al NiAl. Hot corrosion resistance of the aluminide coatings can be improved by increasing the thickness of the outer layer.
In the burner rig tests at 850°C or below, the aluminide coatings whose outer layer thicknesses are about 80μ are more hot corrosion resistant than the platinum-aluminide coatings made by electroplating of platinum of 7μ thickness and aluminizing at 1120°C. This difference is attributed to the preferential attack of the PtAl2 dispersed in the outer layer of the platinum-aluminide coatings.
In the burner rig test at about 1000°C, the platinum-aluminide coatings are more hot corrosion resistant than the aluminide coatings, because of dissolution of the undesirable PtAl2 particles into the matrix and the increased Pt concentration in the coating layer, both due to the rapid diffusion of atoms at the high temperature.抄録全体を表示PDF形式でダウンロード (11371K) -
間渕 秀里, 吉村 恒夫, 小林 弘昌, 福住 達夫1983 年 69 巻 8 号 p. 1022
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーPDF形式でダウンロード (272K) -
前原 繁1983 年 69 巻 8 号 p. 1023-1024
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーPDF形式でダウンロード (534K) -
前川 昌大, 小野 玲児, 伊藤 公久, 原 義明, 松宮 徹, 吉田 和彦1983 年 69 巻 8 号 p. 1027-1029
発行日: 1983/06/01
公開日: 2009/06/30
ジャーナル フリーPDF形式でダウンロード (522K)
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