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Volume 34, Issue 10
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Nobuhiko Iwao, Minoru Otaguchi, Shigeyasu Koda1970 Volume 34 Issue 10 Pages 983-987
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of pre-ageing at 18°C on the subsequent isothermal ageing at 100°C was studied in a Fe-0.028 wt%N alloy by means of internal friction technique and transmission electron microscopy. It was observed that very fine particles were nucleated during pre-ageing at 18°C and the nucleation of these particles was completed after 100 hours at 18°C. These particles grow in size more or less by the subsequent ageing at 18°C or at 100°C. It was found that when these particles began to grow at 18°C or 100°C, there was a sudden decrease in the internal friction of the aged specimen. This may be caused by the decrease in the concentration of nitrogen remaining in the solid solution. From the data of internal friction measurements, the activation energy for the nucleation of the particle was estimated to be about 15000 cal/mol, which agreed well with the value for the diffusion of Nitrogen in α-Fe.View full abstractDownload PDF (2495K) -
Masaharu Yamaguchi, Genjiro Mima1970 Volume 34 Issue 10 Pages 988-992
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe 475°C embrittlement of Fe-Cr and Fe-Cr-V alloys can be removed completely by reheating the alloys around 600°C. In the present paper the process occurring in reheating of Fe-Cr and Fe-Cr-V alloys aged at 480°C has been discussed.
The electrical resistivity and hardness changes produced during reheating have been measured. The process of the recovery of electrical resistivity during reheating has been found to obey a first order chemical rate equation and to be characterized by a considerably higher activation energy than that for the diffusion of chromium and vanadium in iron. From such an analysis the reheating process of Fe-Cr and Fe-Cr-V alloys aged around 500°C has been confirmed to be associated with the resolution of Cr-rich precipitates into Fe-rich matrix.View full abstractDownload PDF (1133K) -
Hideo Abe, Kazumasa Togano1970 Volume 34 Issue 10 Pages 993-996
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe texture of the columnar crystal zone in a Zn-1.5%Cd alloy ingot solidified from the flowing melt was studied by the X-ray pole figure method. The texture, represented by a plane parallel to the chilled surface and an axis parallel to the flow direction of the melt, can be described as the (10\bar10)[0001] orientation tilted approximately 27° to the upstream of the melt, while the columnar crystals are tilted by 24°∼28° to the same direction. The development of this texture can be interpreted by the selective growth of the columnar crystals with cellular dendritic interface which have the ledges vertical to the flow direction of the melt.View full abstractDownload PDF (1034K) -
Ryutaro Jimbou, Minoru Nemoto, Hajime Suto1970 Volume 34 Issue 10 Pages 997-1001
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to investigate the availability of the so-called Hall-Petch relation to some ultra-fine polycrystals which consist of sub-micron size grains, vapor-deposited films of silver and copper of about several microns of thickness were prepared on cooled glass substrates in vacua of about 1×10−6 mmHg. The microstructures of specimens were observed by means of transmission electron microscopy and tensile tests were carried out with an Instron-type machine. From these works, it was confirmed that the availability of the Hall-Petch relation to the ultra-fine grain size of about 0.1μ was fairly good.View full abstractDownload PDF (1634K) -
Masao Fujii, Makoto Kumada1970 Volume 34 Issue 10 Pages 1001-1004
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study of the pitting dissolution in the cold-worked 18Cr-8Ni stainless steel was carried out by means of measurements of the pitting potential, the incubation period and the number of pits. The results obtained are summarized as follows:
(1) Although the pitting potential of cold-worked specimens in 1N-H2SO4+0.5 mol-NaCl solution is less noble than that of annealed specimens (+0.32 V vs. SCE), it is approximately constant over all the degrees of cold work and the value is +0.22 V vs. SCE. The incubation period of pits becomes shorter with increase in the degree of cold work. The weight loss by the pitting dissolution increases with the degree of cold work.
(2) When specimens are locally cold-worked, pits have concentrated on the cold-worked surface. However, the pit density has a maximum at 7 to 10% of cold work.
(3) Pits are easily formed on the regions which have defects in the surface film and are active in terms of energy.View full abstractDownload PDF (1354K) -
Masao Fujii, Makoto Kumada1970 Volume 34 Issue 10 Pages 1005-1011
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study has been carried out in order to investigate the effect of the oxide film on the pitting dissolution in 18Cr-8Ni stainless steel. The following results were obtained:
(1) Pits donot initiate at sites on which the film dissolves generally.
(2) The number of pits decreases with the time for formation of a passive film. This is due to the fact that defects are covered with the passive film.
(3) The number of pits increases remarkably on the oxide film formed at high temperature. It is likely to be due to the local formation of defects formed on the oxide film, but details of the defects remain unknown.
(4) Deformation before and after the formation of the oxide film affects noticeably the pitting corrosion.View full abstractDownload PDF (2637K) -
Kôichi Arai1970 Volume 34 Issue 10 Pages 1011-1016
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe catalytic effects of cupric sulfide on the aqueous oxidation of zinc sulfide in dilute hydrochloric acid solutions are studied in order to obtain data on acidic leaching. The test solutions used are dilute hydrochloric acid solutions containing sodium chloride with pH values 1∼3 and oxygen gas.
The amounts of zinc sulfide and cupric sulfide suspended in the solutions are 10−2∼10−1 M/L. The solutions are maintained at a constant temperature between 25°∼60°C and stirred at 600 rpm.
The experimental results obtained are as follows:
(1) The main dissolution reaction of zinc sulfide in the acidic solution containing oxygen is a type of hydrogen sulfide formation and shows a parabolic dissolution behavior. The reaction is mass-transport control.
(2) The dissolution reaction of cupric sulfide in the solution is S0 producing type. The reaction is small at first and then increases with the lapse of time. The rate of dissolution is accelerated with increasing cupric sulfide suspended in the solution, elevating temperature and lowering pH values.
(3) The hydrogen sulfide formation type reaction of zinc sulfide and the dissolution rate of Zn2+ ion are decreased by the activation treatment of zinc sulfide. The decrease of the rate in the dissolution of activating zinc sulfide is caused by the decrease in surface area of the ore.
(4) The dissolution of Zn2+ in the zinc sulfide+cupric sulfide mixture ore is accelerated with elevating temperature, lowering pH values and increasing concentration of cupric sulfide suspended in the solution. The acceleration of the S0 producing type reaction in the dissolution of the mixture ore is caused by the formation of a galvanic cuople of the ZnS-CuS system. In this case, ZnS serves as the anode and CuS exists as the cathode to the reduction of aqueous oxygen in the solution.View full abstractDownload PDF (1978K) -
Masamichi Kowaka, Hiroo Nagano1970 Volume 34 Issue 10 Pages 1017-1022
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe previous reports showed the rapid laboratory test methods and the mechanism of sulfur dewpoint corrosion of steels in the low temperature parts of boilers. An extensive study was undertaken to develop a steel that would be resistant to the sulfur dewpoint corrosion by using the rapid laboratory test methods, which have a good correlation with the field tests. The present work is concerned with the effect of alloying elements on the sulfur dewpoint corrosion of copper steels. The results of the study were shown as follows:
(1) As the effect of alloying elements of copper steels by the immersion test in 30%H2SO4 at 60°C, i.e. the first step of the sulfur dewpoint corrosion, S (0.010∼0.035%) had a pronounced beneficial effect followed by Sn, As, Sb and Si. The marked detrimental effect was observed for P, Zr, Y, W, Ti, V and Cr (>5%) followed by C and Cr (≤5%).
(2) As the effect of alloying elements of copper steels by the immersion test in 85%H2SO4 at 160°C, i.e., the second step of the sulfur dewpoint corrosion, Si (≥0.2%) had a pronounced beneficial effect followed by P, Zr, V, W, Mo and Ti. The detrimental effect was observed for Cr (>5%).
(3) As the effect of alloying elements of copper steels by the immersion test in the mixture of 85%H2SO4 and active carbon at 110°C, i.e. the third step of the sulfur dewpoint corrosion, Cr and B had the beneficial effect and the detrimental effect was observed for Si (≥0.8%) in Cu-Cr steels, V (≥0.4%) in Cu-B steels, and As and Sb (≥0.1%) in Cu steels.
The corrosion resistant steel composition would be selected on the basis of the above findings.View full abstractDownload PDF (1004K) -
Masamichi Kowaka, Hiroo Nagano1970 Volume 34 Issue 10 Pages 1022-1028
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSelecting some essential and important alloying elements from the point of view of sulfur dewpoint corrosion, the anodic polarization curves of copper steels in 85%H2SO4 at 110°C have been obtained for understanding their effect on the passivation behavior of the steels. The results of the study were shown as follows.
(1) Effect of P, V, Zr, As and Cr (containing about 0.5%) on the anodic bahavior of 0.5%Cu-0.5%Ni steel: Cr followed by P was the most effective element in decreasing the primary passive current density (p.p.c.d.). On the other hand, As resulted in a remarkable increase in both the primary passivation current density and p.p.c.d., Zr and V had little effect on the polarization curve.
(2) Effect of C, B and Cr on the anodic behavior of 0.3%Cu steel: Increasing C up to 0.45% resulted in some reduction of the secondary passive current density, and 0.3% of boron a remarkable decrease in the p.p.c.d. Both elements shifted the corrosion potential to the noble direction. For the effect of less than 18%Cr, the steels containing Cr 18% resulted in lowering p.p.c.d. while 5%Cr resulted in an increase in the current density more than mild steel.
(3) Effect of Si and Mn on the anodic behavior of 0.3%Cu-1%Cr steel: Increasing Si up to 2.76% resulted in a remarkable rising of the primary passive current density, whereas increasing Mn up to 1.45% resulted in a large reduction of p.p.c.d. Increasing Si also decreased the secondary passive current density to some extent.
(4) In general, the corrosion resistant low alloy steels to the sulfur dewpoint corrosion had a comparatively lower primary passive current density than that of the non-corrosion resistant steels.View full abstractDownload PDF (2290K) -
Hakaru Masumoto, Yûetsu Murakami, Masakatsu Hinai1970 Volume 34 Issue 10 Pages 1029-1033
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMasumoto et al. previously discovered that alloys near in composition to Ni3Mn exhibited high permeability when these alloys had an optimum degree of order, and named them Nimalloy. In the subsequent work on the effect of various element additions on the properties of Ni-Mn alloys, the highest initial permeability of 121000 and the highest maximum permeability of 643000 have been obtained in Ni-Mn-Fe-Cr-Mo alloys.
The results show that with increasing Ta content, the permeability of Ni-Mn alloys increases gradually at the beginning and later rapidly attains a maximum, and then decrease gradually. The highest initial permeability of 20470 is obtained on the alloy composed of 75.88%Ni, 19.47%Mn and 4.65%Ta when cooled at a rate of 240°C/hr from 900°C and baked at 440°C for 64 hr, and the highest maximum permeability of 84800 on the alloy of 75.37%Ni, 19.08%Mn and 5.55%Ta when cooled at a rate of 240°C/hr from 900°C and baked at 440°C for 65 hr. The latter alloy shows a coercive force of 0.0253 Oe and a magnetic hysteresis loss of 50.85 erg/cm3/cycle for the maximum magnetic induction of 5000 G, and its electrical resistivity being 52.7 μΩ-cm at 20°C.View full abstractDownload PDF (1737K) -
Takashi Sakaki1970 Volume 34 Issue 10 Pages 1034-1040
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA spectrophotometric method with thiomalic acid for the determination of molybdenum was investigated, and applied to the direct determination of molybdenum in high alloy steel. The molybdenum thiomalic acid complex is formed quantitatively in a sulfuric acid-sodium acetate solution medium of pH 3.0∼4.5. The absorption maximum of this complex is at a wavelength of 365 nm.
Hydrochloric, nitric and perchloric acids do not interfere with the formation of a molybdenum thiomalic acid complex, but phosphoric, tartaric, citric and oxalic acids interfere. The presence of sulfuric acid increases slightly the absorbance for the determination of molybdenum, but its effect appears constant in the range from 1 to 5 mL as sulfuric acid (1+1).
The presence of copper, iron (II) and tungsten increases the absorbance for the determination of molybdenum, and the presence of niobium, tantalum, titanium and zirconium decreases. However, the effect of the copper can be masked by using thiourea, the effect of the iron (II) appears constant in the range from 10 to 20 mg, and the effect of the tungsten can be eliminated by measuring the absorbance at the wavelength of 400 nm. The effect of the niobium, tantalum, titanium and zirconium can be masked by using sodium fluoride.
The sample was fumed with sulfuric acid containing ammonium sulfate for dissolving completely the precipitated niobium, tantalum and tungsten after the sample was dissolved in aqua regia containing ammonium bifluoride, and the sample solution was prepared by adding sodium fluoride for preventing the hydrolysis of the niobium, tantalum and tungsten in the sample solution.
As a result of the experiment, the author succeeded in establishing a method in which 0.5 to 20% of molybdenum in high alloy steel can precisely be measured without difficulty.
The molybdenum contents in actual samples were measured by this method with satisfactory results.View full abstractDownload PDF (2309K) -
Sakae Takeuchi, Hiroshi Katsuta1970 Volume 34 Issue 10 Pages 1040-1047
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn the previous work it has been found that the TiS2 phase existing in the range of TiS2 to TiS1.82 has a lattice structure of the CdI2 type with some amounts of vacancies in the (00,0) site and of Ti atoms in the (00,1⁄2) interstitial site, their concentration depending upon the atom ratio S/Ti. In this paper the dependence of the equilibrium pressure of S2 gas atmosphere surrounding the crystal upon the above-mentioned lattice defects and the excess concentration of Ti is discussed from the viewpoint of statistical thermodynamics.
(1) It is assumed that these lattice defects are not generated by the thermal motion of atoms but come from the following dissociation process on the crystal surface
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by which S atoms remove to the atmosphere and Ti atoms diffuse into vacant sites and interstitial positions.
(2) Under the above assumption a partition function of the crystal phase is calculated as a function of the concentration of excess Ti y, a factor q giving fraction of excess Ti atoms occupying the vacant sites and the interstitial positions, and the number of conduction electrons n.
(3) From comparison of the observed relation between q and y with theoretical one deduced from the above partition function, the energy (Eβ−Eα) required to replace a Ti atom from the (00,0) site leaving behind a vacancy to the interstitial site is evaluated, and a possible cause of vacancy and interstitial Ti atom is discussed from the value of (Eβ−Eα).
(4) The equilibrium S2 pressure is calculated as a function of q and y, which is in good agreement with the pressure-composition curves for the TiS2 phase observed by Abendroth.View full abstractDownload PDF (2061K) -
Masamichi Kowaka, Hisao Fujikawa1970 Volume 34 Issue 10 Pages 1047-1054
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe commercial grades of austenitic stainless steel (18Cr-10Ni) may be subjected to stress corrosion cracking when exposed to tensile stress and certain chloride environments. An extensive study was undertaken to develope a steel resistant to stress corrosion cracking. The influence of phosphorus and nitrogen in austenitic stainless steels on stress corrosion cracking has been investigated in boiling MgCl2 at 154°C by the U-bend and tensile method. The results of the study showed the detrimental effect of phosphorus and nitrogen and the interaction of these elements on the sensitivity to stress corrosion cracking. A new stainless steel resistant to stress corrosion cracking can be developed by controlling the contents of phosphorus and nitrogen in 18Cr-10Ni stainless steel.
The results were understood by observing the dislocation structures of these steels, by measuring the general corrosion rates and potential-time relations in boiling MgCl2 solution at 154°C.View full abstractDownload PDF (2811K) -
Masamichi Kowaka, Hisao Fujikawa1970 Volume 34 Issue 10 Pages 1054-1062
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo develope a new stainless steel resistant to stress corrosion cracking, the effects of several elements on stress corrosion cracking in boiling MgCl2 solution have been studied. The results of the study showed that carbon, silicon and sulfur (<0.1 wt%) were beneficial and molybdenum, copper and chromium were detrimental. Manganese had little effect and is detrimental at its higher content.
Carbon, sulfur, molybdenum and copper increased the resistance to general corrosion in boiling MgCl2 solution at 154°C.
It is also understood from the experimental results of potential-time relations. The relation between stress corrosion and general corrosion has been confirmed.View full abstractDownload PDF (2653K) -
Kenzaburo Kumada, Yoshitaka Sumitomo, Soji Nenno, Masahiko Yamamoto1970 Volume 34 Issue 10 Pages 1062-1066
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe structures resulting from liquid-quenching and subsequent low temperature aging of Al-Mg alloys containing magnesium up to 36.8 at% were studied by transmission electron microscopy and X-ray diffraction. The L12 type superlattice Al3Mg was found to form in both 21.2 and 26.2 at%Mg alloys which had been liquid-quenched and subsequently aged at 100°C for about half an hour. The size of anti-phase domains ranges from 100 to 300 Å.View full abstractDownload PDF (1321K)
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