Tetsu-to-Hagane

STUDIES ON THE SINTERING MECHANISM OF IRON ORE PELLET (I)

Nobuo Nakamura, Yutaka Sato

1957 Volume 43 Issue 6 Pages 619-623
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_619

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In the previous paper, (Tetsn-to-Hagané vol, 39 (1953) p 297; Nippon Kinzoku Gakkaisi, 17 (1953) 122; 126 the authors described on the agglomerating mechanism of green pellets. This report deals with the sintering mechanism of pellets at elevated temperatures. At first, the authors observed a great difference in the microstructure of a sintered pellets which had contained a little carbon powder before it was roasted in comparison with pellets from the combustion-chamber-type pelletizing furnace. In the former one, there were angular hematite crystals caused by grain growth of magnetite in earlier time of roasting, but the latter was usually constructed with hematite crystals network.
According to this fact, the relation between grain growth of iron oxide crystal and the atmospher of roasting was very important. And then the authors investigated the phenomena of colour changes of roasted pellets by electron-diffraction, and decided that the colour (dark blue) was only caused by the dissociation of ferric oxide film, and it suggested that the dissociation should have promoted the bonding of each particle.
On the other hand, the separation of water and some amount of basic gangue increased the bonding in the form of a solid reaction.

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STUDIES ON THE DESULPHURIZATION OF MOLTEN PIG IRON BY MANGANESE (I)

Mn-S Equilibrium in C-saturated Molten Iron-Part 2

Kokichi Sano, Michio Inouye

1957 Volume 43 Issue 6 Pages 623-627
Published: June 01, 1957
Released on J-STAGE: January 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_623

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Refer to Part 1 p. 517 of May, 1957 issue, Tetsu-to-Hagané

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AERODYNAMIC CONSTITUTION OF OPEN-HEARTH FURNACE (IV)

Functions of the Furnace Chamber

Hidefumi Hasimoto

1957 Volume 43 Issue 6 Pages 628-632
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_628

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The furnace chamber of the open-hearth furnace is the place where combustion and heat transfer is performed. The flow in that portion determines the performance of combustion and heat transfer. The burner jet induces vortices which enclose and squeeze the air flow into it.
In the entrance of the chamber, vortex A takes place between the jet and bath, vortices B occupy the spaces both the front and back sides of the jet, and vortex C comes of the return flow under the ceiling and occupies the space between the ceiling and the jet. The burner jet splashes on the bath and runs up the walls towards the roof, in this way vortices D come into being and they link with the vortex C by way of the return fiow.
Model studies on the furnace chamber to get the rational chamber flow explained the following points:
(1) The chamber spaces should be balanced in front and back of the burner line, therefore the distances of the walls from the burner line should be nearly equal.
(2) The shoulder angle (θ) should be 40-60°, and its standard is 53°.
(3) The height of the main roof should be 37-55% of the chamber width. Its standard is 46%, and the smaller ratio will be applied to the larger furnace.
(4) The length of the chamber is not greater than 3 chamber widths, the bath length is about 2.6 chamber widths and about 3 bath widths.

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CUPOLA EXHAUST GAS ANALYSIS METHOD

Toshihiko Shimomura, Masato Yamamoto

1957 Volume 43 Issue 6 Pages 632-637
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_632

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The authors analysed the exhaust gas from cupola for rationalization of cupola operation, and also for the purpose of getting a high-strength cast iron of constant composition which are desired. For such kind of gas analysis, hitherto, the chemical method, such as the Orsat or Hemple gas analysis equipment had wholly been adopted. But later the physical method to examine CO₂ quantity by measuring electric conductivity or specific gravity of CO₂ in exhaust gas has mostly been used. This physical method can be carried out automatically but it is subject to lack in exactness by the influence of other kind of gases than. CO₂.
It was found that when the Orsat analysis equipment was used jointly with the CO₂ meter of electric-conductivity type for the calibration of its meter, the absolute value of CO₂ was not obtained unless they paid special attention to CO₂ absorbent and the absorption pipet for Orsat method. Especially in case of continuous measurement, other combustion analysis method must be adopted at the same time.
The authors made determination of not only CO₂, O₂ and CO but H₂ & CH₄ also, by the precise analysis equipment, and also closely analysed each of H₂S and SO₂ by another chemical method, for the purpose of getting the reference data for the performance test of CO₂ meter.
Regarding the above mentioned matters, all are carried out by way of test in the laboratory, but as a result of practical operation of an absoption semi-automatic CO₂ meter manufactured for trial which had been cleared away from any error of meter method and any trouble with Orsat method, it was found that this meter was simple both in construction and operation and with it one could measure speedily. Therefore the authors are using this meter at present.

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EFFECTS OF THE MILL ARRANGEMENTS ON THE PROPERTIES OF MILD STEEL WIRE RODS

Tadashi Ohtake, Naoki Eguchi, Isao Kimura

1957 Volume 43 Issue 6 Pages 637-642
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_637

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In order to examine effects of the mill arrangements on some properties of [the wire rod of mild steel and the wire drawn from it, a comparative study was made of the hot rolled wire rods produced at Hikari and Yawata plant of Yawata Iron & Steel Co., Ltd.
To quote the different points between these two works, the former is the 4-strand high speed continuous wire rod mill manufactured by Siemag Co., and the latter the semicontinuous wire rod mill (a combination of a continuous and a Garret's type mill).
The following are the chief results explained:-
1. The roundness of hot rolled rods of Hikari works was better than that of Yawata works.
2. The mill-scales on the hot rolled rods were 12mg/cm at Hikari and 25mg/cm at Yawata, respectively, and therefore the pickling time for Hikari rods was much shorter than that for Yawata's.
3. The tensile strength and the yield point of Hikari rods were higher than those of Yawata rods, though the elongation and the reduction of area were higher.
4. In point of microstructure, it was noticed that ferrite grains of Hikari rods were a bit smaller than those of Yawata's.
5. The above-mentioned characteristics of the Hikari rods presumably were caused by the effective water cooling to be applied after the rods were passed through the final rolls.
6. The mechanical properties of the wire drawn depended on the intial rod properties of the rods and chemical compositions. Therefore tensile strength of the wire drawn from Hikari rods were higher, but reduction of area of the wire were also influenced by the draw ing method, particularly with the increase of the cold reduction.

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EFFECT OF Mn ON THE PROPERTIES OF Cr-Mo CASE-HARDENING STEEL

Kiichiro Shinji, Kingo Kiyonaga

1957 Volume 43 Issue 6 Pages 642-646
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_642

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Effects of Mn on various properties of Cr-Mn-Mo case-hardening steel added with Mn from 0.6 up to 2.3% were investigated. At low quenching temperature, addition of Mn effectively decreased the distortion ratio with sufficiently increased quenched hardness. Especially the specimens containing 1.6% Mn showed the superior result. Strength much increased in Cr-Mn-Mo case-hardening steel, though toughness was sacrificed to some extent. Addition of Mn improved abrasive properties, but when combined with SNC-3, the good results could not be obtained.

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STUDIES ON INDUSTRIALIZATION OF MT PERMANENT MAGNET

On the Heat Treatment and Structure

Tokushichi Mishima, Noboru Makino

1957 Volume 43 Issue 6 Pages 647-652
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_647

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The optimum heat treatment and the structure of MT magnet was investigated on the specimens consisted of representative composition. This alloy is provided with poor magnetic properties when it was quenched from 1150°C or lower temperature. The critical temperature is therefore considered to be 1200°C, and those samples quenched from this temperature showed a uniform austenite solid solution. When holding time at quenching temperature was too long, magnetic properties, especially residual induction, was deteriorated by decarburisation. The most adequate period of holding time is from 20 to 30 minutes.
Cooling rate also strongly affects the magnetic properties in case of Fe-Al-C alloys. It is related to the formation of β martensite which is essential for retaining high coercive force. A favourable state for β martensite seems to be produced only by proper cooling rate. Among several cooling methods, oil-quenching gave the best result and water-quenching at 20°C gave the most inferior result.
Since the quenched specimen is consisted of austenitic phase, a part of its structure needs to be converted to ferromagnetic martensite. According to aging curve, the maximum magnetic properties was obtained by tempering for 60 or 120 minutes at 300°C. It is noteworthy that the second hardening occurs at around 500°C in the course of tempering, accordingly, the peak of magnetic properties are recognized at about 300°C and 500°C,
MT magnet turns to machinable by means of annealing. If the annealing temperature reaches 1, 000°C, deterioration of magnetic properties are unavoidable, The annealed specimen was consisted of α phase and double carbide.

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INVESTIGATION ON ACID-RESISTANT HIGH-SILICON IRON (II)

Effects of Alloying Elements on Mechanical Properties, Corrosion Resistance and Shrinkage. -Part 1.

Hiroshi Sawamura, Osamu Tajima, Kyoichi Akamatsu, Hirohito Muranaka

1957 Volume 43 Issue 6 Pages 652-657
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_652

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The effects of Si and C, the main constituents of the alloy in question, on the mechanical properties, corrosion resistance, and shrinkage of acid-resistant high-silicon irons have already been reported by the authors. Successively, in the present investigation, the effects of various alloying elements, i.e., P, S, V, Ti, Al, As, Sn, Mn, Ni, Cr, Mo, Co, Cu and W on these properties have been studied.
The results are summarized as follows:
(1) The elements that had favourable effects on the transverse strength of high-silicon iron were as follows: Ni (0.7%), Co (0.3%), Cr (0.6%), Mo (3%), W (0.8%), V (0.09-0.5%) Ti (0.3%), Al (0.06%), and Cu (0.3-3%). The percentage in parenthesis indicated the optimum content.
(2) The elements that promoted a growth of graphite, such as Cu and Al, decreased the Rockwell hardness, while the elements, the so-called carbide stabilizers, that diminished the size of graphite and gave favour to form hard carbide-phases, such as Mn, P, Cr and Mo increase the Rockwell hardness.
(3) The corrosion resistance to sulphuric acid was improved by additions of Mn, P, Ni, Co, Cr, V, Cu, and As. Among these elements, Cu was most effective. It was adversely affected by Sn and S. For hydrochloric acid Mo and Ni had good effects while Sn and P had deleterious effects.
(4) The shrinkage of high-silicon irons decreased by additions of all alloying elements in the present tests except As.

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TEMPERATURE MEASUREMENT OF IRON AND STEEL SAMPLES IN A GRAPHITE CRUCIBLE FOR GAS ANALYSIS

Noboru Yoneda

1957 Volume 43 Issue 6 Pages 657-662
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_657

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For the purpose of measuring of the accurate temperature of gas extraction in the gas analysis in iron and steel, the effective emissivity of samples was determined. It was found that the emissivity should be calculated approximately by the size of the graphite crucible used in the analysis.

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SOME PROBLEMS ON THE MANUFACTURE OF SEAMLESS STAINLESS STEEL TUBINGS BY THE MANNESMANN-PLUG MILL PROCESS

Shoichi Nakajima

1957 Volume 43 Issue 6 Pages 663-668
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_663

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Among various manufacturing methods of seamless stainless steel tubes from billet of stainless steel, there is the Mannesmann-plug mill process by which a comparatively good tube-making efficiency is ordinarily to be expected.
However, stainless steel tube-making by this method involves pretty difficult problems from its technical view-point, and it was of a quite recent date that the mass-production by this method was enabled to be carried out.
The author discussed with particular reference to the points at issue including those of the past and the future, for the manufacture of stainless steel tubes by this Mannesmannplug mill process.
Throughout all the processes from billet-heating to final finish, the most difficult problem from the technical point of view mainly lies in the piercing process on which the author discussed rather in details, dealing with the other points according to priority.

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[title in Japanese]

1957 Volume 43 Issue 6 Pages 669-674
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_669

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[title in Japanese]

[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...

1957 Volume 43 Issue 6 Pages 675-680
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_675

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[title in Japanese]

1957 Volume 43 Issue 6 Pages 681-684
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_681

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[title in Japanese]

1957 Volume 43 Issue 6 Pages 682-684
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_682

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[title in Japanese]

1957 Volume 43 Issue 6 Pages 688-690
Published: June 01, 1957
Released on J-STAGE: May 26, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.43.6_688

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