巻号一覧
54 巻, 4 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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磯部 晋, 今村 元昭, 野田 俊治1983 年 54 巻 4 号 p. 227-237
発行日: 1983年
公開日: 2009/05/25
ジャーナル フリーThe purities of melting stocks and solidification conditions control the soundness of single crystal castings of a γ'-strengthened Ni-base superalloy. In this study, the effects of impurities (O, N, C and S) and solidification conditions on the defects such as nonmetallic inclusions, freckle and microporosity in NASAIR 100 single crystal cast through the liquid metal cooling (LMC) method were investigated. The following results were obtained.
(1) The impurities suppressed under the values as shown below will not impare the castability of the alloy into single crystals, because they hardly enlarge the melting range for the puriest one.
O≤12ppm, N≤33ppm, C≤150ppm, S≤60ppm
(2) The above LMC single crystals do not contain any freckle.
(3) The melting stocks contaminated by the impurities as shown below transfer nonmetallic inclusions to the above LMC single crystals, such as Al2O3, (Ti, Ta) N, (Ti, Ta) C or (Ti, Ta)xS.
O≥12ppm, N≥10ppm, C≥50ppm, S≥20ppm
(4) The LMC single crystals embody a very few and small microporosity, totally around 0.1% in areal fraction and each less than 80μm in dia. The impurities in melting stocks listed at (1) will not affect the porosity in castings, while the γ/γ' eutectics originated from the constitutional supercooling under the large product of G and R subdue the evolution of it.抄録全体を表示PDF形式でダウンロード (11636K) -
小畑 英一1983 年 54 巻 4 号 p. 238-245
発行日: 1983年
公開日: 2009/05/25
ジャーナル フリーThe overview covered the case history of marine diesels in Japan since the first domestic production till now, the qualities of the fuel oil at present and in future, and the requirements for heat resisting alloys fabricated into valves and hardfaces of marine engines, mainly low-speed 2cycle types, burning the above oil.
Subsequently photos demonstrated the typical damage of valves in active engines, while the ordinary measures were introduced to prevent them from degrading.
Finally the author analyzed the state of the art and tried to predict the trend in heat resisting alloys for valves of marine diesels.抄録全体を表示PDF形式でダウンロード (4473K) -
斉藤 誠, 飯久保 知人1983 年 54 巻 4 号 p. 246-252
発行日: 1983年
公開日: 2009/05/25
ジャーナル フリーThe hot corrosion behaviors of intake valve steels having various Cr content were investigated under several test conditions. Results obtained were summarized as follows.
1. Corrosion loss of intake valve steels is affected by testing temperature, Cr content and corrosion atmosphere. Molten PbO·MO mixture formed above 730°C severely accelerated hot corrosion.
2. Addition of Cr is effective for improvement of corrosion resistance of intake valve steels in still air, in PbSO4 and in PbO. The degree of improvement depends on the corrosion atmosphere.
3. On low Cr steel, weight loss in still air is same to that in PbO. However, accelerating-corrosion is observed on Cr-bearing steels under low temperature range in which any molten oxide was not observed.抄録全体を表示PDF形式でダウンロード (2949K) -
磯部 晋, 岡部 道生1983 年 54 巻 4 号 p. 253-264
発行日: 1983年
公開日: 2009/05/25
ジャーナル フリーA typical martensitic precipitation hardening stainless steel, 17-4PH, contains the reverted austenite from the martensitic matrix at overage. The authors investigated the kinetics of it and the effect of retained austenite on the properties for overaged materials.
The results are as follows.
(1) The kinetics of the reverted austenite formation is explained by the rate formula of Johnson-Mehl-Avrami, ζ=1-exp(-kt1/2),
where ζ: the volume fraction of reverted austenite,
t: aging time (sec.)
k=1.27×105exp(-Q/RT), Q=33.2kcal/mole.
It shows the reverted austenite plates grow in thickness through the diffusion of austenite formers, Ni and Cu, along the martensite lath or prior-austenite grain boundaries. Lamellar morphologies of the retained austenite prove the above kinetics.
(2) The austenite reverted at lower aging temperatures enriches Ni and Cu, so that it remains stable at room temperature, while the composition of the austenite at higher temperatures reaches the equilibrium, and transforms to martensite unaged on cooling.
(3) The hardness of overaged specimens obeys the rule of mixture,
HRC=0.368Ma+0.058γR+0.108α'
where the volume fractions of each phases are defined below.
Ma: overaged martensite (%)
γR: retained austenite (%)
α': unaged martensite less than 25%.
(4) The retained austenite depresses the tensile strength, especially the proof stress.
0.2%PS=115.5-1.4γR(kgf/mm2)
0.02%PS=107.0-1.9γR. (kgf/mm2)
(5) The larger amount of γR shifts the transition temperatures to lower and the upper shelf values to higher for Charpy impact tests.
(6) The lamellar retained austenite enhances the resistance against stress corrosion cracking in boiling 42% MgCl2 solution.
(7) The lower proof stress material with γR posseses the poorer fatigue strength under NaCl aq. drops.抄録全体を表示PDF形式でダウンロード (7402K) -
小野 清雄, 柳田 稔, 河野 富夫, 柴田 範嘉1983 年 54 巻 4 号 p. 265-274
発行日: 1983年
公開日: 2009/05/25
ジャーナル フリーDevelopment of a leaded free-machining austenitic stainless steel has been tried. The main results obtained are as follows.
(1) The hot workability of the leaded free-machining austenitic stainless steel is greatly improved by controling N and adding about 50ppm B. The improved hot workability is equivalent to that of SUS304 steel.
(2) The corrosion resistance of the newly developed free-machining stainless steel, 304FL, is much better than that of SUS303 steel and comparable to that of SUS304 steel.
(3) The machinability of 304FL is far beyond SUS304 steel and equal to SUS303 steel containing 0.2%S.
(4) 304FL steel has a good cold forgeability and can be rightly cold-headed as SUS304 steel.抄録全体を表示PDF形式でダウンロード (9189K) -
湯川 夏夫1983 年 54 巻 4 号 p. 275-287
発行日: 1983年
公開日: 2009/05/25
ジャーナル フリーPHACOMP has been widely used for alloy development and productions in superalloy industries. It is an empirical method based on the electron vacancy concept and use electron vacancy number of transition metals, Nv, as a parameter to predict the occurence of TCP phases (e. g. σ phases) in superalloys. Although the PHACOMP is now employed as a specification for the quality control of Ni-base superalloys, there still remain some contradictions in the prediction for the occurence of TCP phases. Most of these problems are inherent in the electron vacancy concept, and hence could not be solved by several modified Nv methods so far developed. Recently, the author's group developed new PHACOMP which was based on DV-Xα cluster calculations of electronic structure of alloys. A parameter, Md, which is an average energy level of d-orbitals for alloying transition metals, was obtained for the metals of being important in superalloys. In the new PHACOMP, Md was introduced as a new parameter showing a phase stability of γ austenitic alloys, insted of Nv. In this paper, superiority of Md-PHACOMP over the traditional Nv-PHACOMP was shown through the representation of γ/γ+TCP (σ-and μ-phases) phase boundaries in Ni-, Co-and Fe-base ternary alloys by iso-Md line and the prediction of σ-phase in commercial Ni-and Fe-base superalloys.抄録全体を表示PDF形式でダウンロード (730K) -
西 義〓1983 年 54 巻 4 号 p. 288-296
発行日: 1983年
公開日: 2009/05/25
ジャーナル フリーThe problem of hot corrosion of high-temperature alloys used to aircraft engines and industrial gas turbines has been known for many years. It is usually attributed largely to the presence of sodium sulfate which is formed by reaction between sodium chloride injected from marine environment and sulfur in the fuel.
In this paper, the effects of alloying elements of nickel-base high-temperature alloys on the hot corrosion induced by sodium sulfate are discussed.抄録全体を表示PDF形式でダウンロード (494K) -
今村 元昭1983 年 54 巻 4 号 p. 297-302
発行日: 1983年
公開日: 2009/05/25
ジャーナル フリーDaido has recently developed DS Alloy 80A possessing higher age-hardenability and also established the thermomechanical processing (TMP) to strengthen the forgings of it. The exhaust valves of DS Alloy 80A through TMP prove the excellent performance in marine diesels as follows.
(1) The face has the sufficient hardness and the excellent resistance against hot corrosion, so that the troublesome hardfacing is unnecessary to prevent blow-by.
(2) The head-stem junction withstands the alternating intense load without premature failure, because of the enhanced fatigue strength at elevated temperatures.抄録全体を表示PDF形式でダウンロード (4731K) -
寺井 和人, 河野 富夫1983 年 54 巻 4 号 p. 303-307
発行日: 1983年
公開日: 2009/05/25
ジャーナル フリーA preliminary corrosion test revealed that the 12% Cr steel is the most promising material among various steels for components of continuous galvanizing lines. So the effect of alloying elements, Cr, C, Si, Al and Nb, were surveyed on the properties of alloys to design a new 12% Cr steel. The results are as follows:
(1) Cr and Si enhance remarkably the corrosion resistance against molten zinc, while C, Al and Nb do not affect it.
(2) All of Cr, Si Al and Nb reduces impact values, especially Cr and Si. Finally the composition of a new steel RS 818 was optimized to 12% Cr and 1.8% Si. The field test proved the longer life for RS 818 than for an expensive conventional steel, 25%Cr-12%Ni-1.8%Si, as sink rolls of continuous galvanizing lines.抄録全体を表示PDF形式でダウンロード (215K)
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