Tetsu-to-Hagane

[title in Japanese]

1971 Volume 57 Issue 13 Pages 1861-1862
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1861

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Principles of Deoxidation

Hiroshi SAKAO, Koin ITO, Yoshimoto WANIBE

1971 Volume 57 Issue 13 Pages 1863-1882
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1863

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Identification of Nonmetallic Inclusion in Steel

Minoru SASAKI, Isamu TAGUCHI

1971 Volume 57 Issue 13 Pages 1883-1896
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1883

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Relationship between Nonmetallic Inclusions and Mechanical Properties of Steel

Iku UCHIYAMA, Masae SUMITA

1971 Volume 57 Issue 13 Pages 1897-1911
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1897

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Machinability of Steel and Metallurgical Factors

Toru ARAKI, Shigeo YAMAMOTO

1971 Volume 57 Issue 13 Pages 1912-1932
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1912

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On the Dissolution Process of Deoxidizer into Molten Iron and the Mechanism of Formation of Oxide Inclusions

Koin ITO, Kanji KONDO, Mahito MAEDA, Kokichi SANO

1971 Volume 57 Issue 13 Pages 1933-1942
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1933

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The dissolution of deoxidizer into molten iron was studied.The distribution of added element in the intermediate layer after solidification was greatly varied with the rate of cooling.Owing to the difference of density between inclusions and matrix, inclusions migrated during their formation and also solidification of the melt.Accordingly, the composition of inclusion varied with the change of concentration of deoxidizer in matrix, but was not exactly in equilibrium with that of matrix containing. It is well known that by the addition of solid Al-Fe alloy containing above 0.3%AI, oxide inclusions formed dendrite clusters.On the other hand, by the addition of molten AI-Fe alloy containing below 2%AI at1600and1800°Cinclusions formed ordinary cloud cluster but not dendrite cluster.The formation of dendrite cluster is assumed to be caused by the orientated coagulation of oxide inclusions induced by some factors such as Al concentration gradient or temperature gradient being present in molten iron.

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Deoxidation of Molten Steel with Deoxidizer Containing Aluminum

Koichi ASANO, Taketo NAKANO

1971 Volume 57 Issue 13 Pages 1943-1952
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1943

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The mechanism on the deoxidation of molten steel with deoxidizer containing aluminum was investigated by using induction furnace.
The results obtained are summarized as follows.
1. Shape of deoxidation products in molten steel is cluster after addition of Al-Mg-Si or aluminum, and is globular after addition of Al-Ca-Si-Mn.
2. Though cluster type deoxidation products appear to consist of isolated particles on a polished cross section, they are in dendritic structure in the three dimensional configulation.
3. Deoxidation products after addition of Al-Mg-Si or aluminum have a big size as clusters and float up in molten steel very rapidly. But deoxidation products after addition of Al-Ca-Si-Mn have a small size as isolated globular products. Consequently, the decreasing rate of total oxygen in molten steel is much faster with the addition of Al-Mg-Si or aluminum than with that of Al-Ca-Si-Mn.

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On the Deoxidation of Liquid Iron with Silicon and the Formation of SiO₂Inclusions during Solidification

Rokuro SAKAGAMI, Takashi SASAI

1971 Volume 57 Issue 13 Pages 1953-1962
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1953

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The mechanism of the deoxidation of liquid iron with Si and the formation of Si0₂ inclusions during solidification were studied on the basis of the various facts.
The conclusions obtained were as follows.
1) The deoxidation reaction is not completed immediately after addition of Si and the supersaturation in liquid iron continues for several minutes.
2) The SiO₂ particle does not grow by the collision and coalescence with other particles, but grows principally by the diffusion of the solute atoms in the melt.
3) The growth of SiO₂ particle is controlled by the interfacial reaction.
4) The progress of the interfacial reaction is represented by the following equation.
SiO₂+O (abs) =Si+2O+O (ads)
5) The process of the deoxidation with Si should be discussed taking account of the isolation of the SiO₂ inclusion from the melt and the decrease of the concentration of the dissolved oxygen.
6) The process of the deoxidation and the formation of SiO₂ inclusions during solidification are definitely influenced by nucleation and growth.

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Influence of Crucible Material on the Deoxidation of Liquid Iron with Si

Takashi SASAI, Rokuro SAKAGAMI, Tohei OTOTANI

1971 Volume 57 Issue 13 Pages 1963-1968
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1963

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In order to investigate the influence of the crucible material on the Si-deoxidation, the following experiments were carried out.
Experiment A; The change of concentration of oxygen, silicon and aluminium in liquid iron in an Al₂0₃ crucible after addition of metallic silicon was studied at 1635-C.
Experiment B; The process of the dissolution of the Al₂0₃ crucible into liquid iron deoxidized with various amount of silicon was investigated, by rapidly raising the temperature of the melt from 1550°C to 1635°C and by measuring the change of the concentration of oxygen, silicon and aluminium at 1635°C.
The solubility proluct [%Si][%O] ² at steady state in the experiment A agreed with that in the experiment B, but it varied with the concentration of silicon in liquid iron and there was a maximum at about 0.5% silicon.
It depends also on such an experimental condition as the size of the crucible.
The solubility product is affected not only by the acti ity of Si0₂ which was asorbed on the inner wall of the crucible after deoxidation, but also on the heterogeneity of absorption and the concentrations of silicon and aluminium in liquid iron and of oxygen adsorbed at the interface between the crucible and the melt.

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The Deoxidation of Liquid Iron with Calcium

Yoshio MIYASHITA, Katsuhiko NISHIKAWA

1971 Volume 57 Issue 13 Pages 1969-1975
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1969

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An investigation was made to clarify the basic feature of deoxidation of liquid iron with calcium. In the experiment, calcium metal was added to the bottom part of liquid iron using a silica tube which was inserted into the liquid iron.
The addition of calcium metal in this way gave the high concentration of calcium in the melt and the rapid decrease of oxygen concentration.
The results obtained are as follows:
(1) The concentration of calcium dissolved in the liquid iron is estimated to be at least 0.0103 weight percent at the temperature of 1600°C and in the atmosphere of 1 atm.
(2) The reaction Ca+O=CaO proceeds immediately after the addition of calcium and calcium has been proved to be a very powerful deoxidizer having K′ca= [%Ca][%O] at 1600°C.
(3) When a small amount of calcium is added to the liquid iron in which primary deoxidation products such as SiO₂ or Al₂O₃ are suspended, the concentration of oxygen decreases very rapidly to the equilibrium value calculated from the concentration of deoxidizer.

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Deoxidation of 18-8 Stainless Steel Si, Mn and Al

Shoichi KATO, Hideo YOSHIDA

1971 Volume 57 Issue 13 Pages 1976-1983
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1976

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Eexperiments are carried out to clarify the deoxidation behaviour of Si, Mn and Al is 18Cr-8Ni stainless steel for which strong deoxidizers are needed. The molten 18Cr-8Ni stainless steel, in which Si (0.3 or 0.7%) and Mn (0.4, 0.8 or 1.6%) have already been added, is casted into the ingot of 10 kg after one minute later of Al addition.The oxygen content, the index of cleanliness, the final polishing surface of the samples taken from the ingot and the destribution of the oxide inclusions are investigated together with the identification of the oxide inclusions.
The following results are obtained.
(1) The oxide inclusions vary with increasing amount of Al addition at low Si (0.3%) content, inclusions change as follows: Mn-chromite (MnO-Cr₂O₃)→Mn-Al-chromite (MnO-(Al, Cr) ₂O₃)→Mnaluminate (MnO-Al₂O₃, at high Mn (1.6%) content)→alumina (Al₂O₃), and at high Si (0.7%) content, Mn-silicate (MnO-Si0₂)→Mn-Al silicate (chiefly 3MnO-Al₂O₃-3Si0₂)→alumina (Al₂0₃).
(2) In the case of 0.01% Al addition, the surface defects decrease in spite of the high oxygen content and the high index of cleanliness. These phenomina are attributed to the formation of liquid oxides, i. e. Mn-Al-chromite, Mn-aluminate or Mn-Al-silicates. But the granular alumina and the alumina cluster, which are formed at higher Al addition, give a harmful effect to the polishing surface.
(3) Therefore, the deoxidation with a suitable amount of Al to form the Mn-aluminate in 18Cr-8Ni stainless steel is one of the ways for decreasing surface defects caused by the oxide inclusions.

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Phase Relations of Fe-Mn-S System at 1330° and 1615°C

Nobuo SANO, Mizuko IWATA, Hideto HOSODA, Yukio MATSUSHITA

1971 Volume 57 Issue 13 Pages 1984-1989
Published: November 01, 1971
Released on J-STAGE: December 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1984

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The phase diagrams of solid and liquid Fe-Mn-S systems were determined by using the recent technique such as the levitation melting and electronprobe microanalysis.
The results at 1330°C show that molten sulphide phase is equilibriated with solid iron containing less than 0.14% manganese and contains less than 0.85% manganese.The solid solution of FeS and MnS is in equilibrium with iron containing more manganese than this critical content and it behaves in a slightly negative manner on the basis of Raoult's law.
At 1615°C, the separation into two liquid phases occurs readily with the addition of a small amount of manganese. The compositions of two coexisting phases agree with those previously obtained by KÖRBER and ÖLSEN in spite of the fact that their sulphide was seriously contaminated by the cruicible material. he present results confirm the practical impossibility of the singular desulphurization of liquid iron by manganese.

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Non-Metallic Inclusions in Calcium-Aluminum Complex Deoxidized Steel

Toshio SHIRAIWA, Nobukatsu FUJINO

1971 Volume 57 Issue 13 Pages 1990-2009
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_1990

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In order to reveal the relationship between composition of non-metallic inclusion and condition of deoxidizing by calcium and aluminum, several middle carbon steels (S 45 C) were prepared and sampled from furnace, mold, ingot and forged bar.
Non-metallic inclusions in these samples were investigated on micrographical appearances, cleanliness and the compositions.Compositions of representative inclusions changes from quantitative electron probe microanalysis.It is found that composition of inclusion is not changed during solidification and forging, and the composition of oKide inclusions changes from Mn-Si-O to Al₂O₃ through Ca-Al-Si-O, Ca-Al-O with the increasing amount of aluminum deoxidizer. In case of using rich aluminum deoxidizer, calcium forms CaS or (Ca, Mn) S instead of oxide.
From results of the present experiments, the order of the tendency of reaction between elements is molt-fn steels are as follows;
Tendency to oxygen: Al>Ca>Si>Mn,
sulfur: Ca>Mn>Al,
calcium: 0>S,
manganese: S>0.
These tendencies are also explained from thermochemical standpoint.

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Effect of Ingot-Making Conditions on Non-Metallic Inclusions in Rimming Steel Ingots

Koichi ASANO, Tsuyoshi SAEKI, Yoshio NURI

1971 Volume 57 Issue 13 Pages 2010-2021
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2010

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It is proved that the amount of non-metallic inclusions extracted from middle-rim-zone and from bottom-core-zone is related with the amount of gas evolved during solidification and rimming action.
The amount of non-metallic inclusions in middle-rim-zone becomes less as the amount of evolutional gas from rimming steel ingots gets larger.For example, the cleanest rim-zone of ingot is obtained at the carbon content of 0.07 to 0.09%, at which the amount of evolution gas is the largest.The amount of inclusions in bottom-core-zone is not always corelated with the gas amount, but it is found out that there is a certain range of combination of carbon content and additional amount of aluminum for the least amount of inclusions.

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The Effect of Pouring Conditions on Large Inclusion in Bottom Part of Low-Carbon Rimming Steel Ingot

Takami IKEDA, Keisuke SUMITOMO, Katsukiyo MARUKAWA, Satoru URA

1971 Volume 57 Issue 13 Pages 2022-2028
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2022

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A study has been made of the effect of pouring conditions on large inclusions in bottom part of ingot, the following results have been obtained.
1) The pouring tempereture has the strongest effect on the amount of large inclusion.The temperature becomes lower, the amount of large inclusions increases.
2) The rimming time is an important factor next to the pouring temperature.When the rimming time is short, a large amounts of relatively small size inclusions retain, even if the pouring temperature is sufficiently high.
3) The effect of ingot dimension on large inclusions can not be recognized.Ingot dimension negligible factor compared with two factors mentioned above in the ordinary pouring conditions.
4) Factors influencing the composition of large inclusions were confirmed.The relation, however, between the composition and the amount of large inclusions could not be observed.

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On the Effect of Nonmetallic Inclusions on Ductility and Toughness of Structural Steels

Isao KOZASU, Teruhiko SHIMIZU, Hiroyuki KUBOTA

1971 Volume 57 Issue 13 Pages 2029-2041
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2029

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Ductility and ductile fracture in relation to nonmetallic inclusions has been studied on laboratory melted commercially impure copper bearing steels in various aging conditions and also on low carbon steels with minor alloying additions.The results of light microscopy and scanning electronmicroscopy suggest that the first step of the fracture is cracking and decohesion of elongated inclusions in early stages of deformation.The damaged inclusions form internal necks (as opposed to external neck), and they, in turn, accelerate the final separation process which is formation and coalescence of microvoids associated with submicroscopic spherical oxide inclusions.This two stage mechanism explains general experience of harmful effect of elongated sulfide inclusions and observed duplex dimple pattern of the fractured surface.Change of inclusion shape from elongated to spherical improves ductility probably because of more difficulty for spherical inclusions to form internal necks.The damage of inclusions during deformation and also the final fracture seem to be controlled by dissipated plastic energy to some extent.Although the effect of non-metallic inclusions on toughness is complex, inclusions are generally noted to promote brittleness, but to less extent for the case of elongated inclusions where triaxial stress ahead of crack is relaxed by fissuring along their elongated direction.

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The Effects of Non-metallic Inclusions and Structure on the Fatigue Properties of Deoxidized with Al, Si-Mn and Ca-Si 0.45% Carbon Steels

Toru ARAKI, Tzu-Ye SHIH, Ryuhei SAGAWA

1971 Volume 57 Issue 13 Pages 2042-2056
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2042

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An investigation has been made of the influences of non-metallic inclusions and structure on the fatigue properties of 0.45% carbon steels deoxidized with Al, Si-Mn, and Ca-Si, with alternate bending test.
Results of this study indicate as follows:
1) The nucleation site of a main crack is definitely associated with a larger inclusion than 20p on the specimen surface, regardless of its composition.
2) The effect of inclusion on propagation rate of the fatigue crack seems to be more evident with decreasing tempering temperature of the steels.The crack propagation rate is independent on the kind of inclusions but is dependent on the cleanliness of the steels.
3) The macroscopic crack growth rate is formulated as a function of stress intensity factor range 4K, that may be expressed as: d (2l)/dN= (ΔK) ⁿ/M
where n is a variant exponent and is different from the case of Paris'law.While the value n is a function of composition, structure and inclusion of materials.In the present work, it is found that n varies from 1.45 to 7-69, and the minimum n value is obtained in the steel tempered at a temperature of 400°C.
4) The refinement of sub-grain due to the increase in fatigue cycles or stress amplitude is considered as the result of a process which involves smaller cell formation by multiplication and migration of dislocations.

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Effect of Sulphide Shape on the Cold Forming Properties of SCM22Ca-S Free Cutting Steels

Kunio KUSAKA, Masaaki IWAMARU

1971 Volume 57 Issue 13 Pages 2057-2066
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2057

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The effect of sulphide shape on cold forming properties of SCM22Ca-S free cutting steel containing 0.20%C, 1.00%Cr, 0.20%Mo and 0.05% were investigated.The results ob'ained are as follows.
1) Sulphide shape ratio (width/length) increases linearly with the addition of Al, Zr, and V.
2) Cold forming properties of SCM 22 Ca-S are improved with increasing the sulphide shape ratio, and beyond the sulphide shape ratio of 0.6 cold forming properties become comparable to SCM22 (Base steel).

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Effects of Zr Addition on the Cold Workability of Resulphurized Steels

Takeji ARAKAWA, Toshiro YAMAMOTO, Takeshi AIZAWA

1971 Volume 57 Issue 13 Pages 2067-2075
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2067

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Effects of Zr addition of up to 0.2% on the cold workability of low carbon resulphurized steels, containing up to 0.2%S are investigated in spheroidized and banded structures.Although a remarkable improvement of the compressive ductility is observed in Zr treated spheroidized steels with increaring Zr/S ratio in steel, Zr addition has no effect on the compressive ductility of annealed steels showing banded structure.The tensile ductility seems not to be enhanced by Zr addition. Relationship between the shape of sulphides and the compressive ductility is discussed.

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Effect of Deoxidation on Nonmetallic Inclusions in Steel and the Machinability

Kou TASAKA, Tadahisa AKASAWA, Sakae KATAYAMA, Kazuya KUROIWA

1971 Volume 57 Issue 13 Pages 2076-2089
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2076

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The machinability of a specially deoxidized free-cutting steel both in turning and drilling has been studied in comparison with that of ordinary steels and leaded steels, for the purpose of clarifying the relations between the machinability of steels and their nonmetallic inclusions.
The tool life, for turning the specially deoxidized free-cutting steel with carbide or ceramic tools is definitely longer than that of an oridinary or leaded free-cutting steel, apparently because of the effect of the oxide layer formed on the tool face. The composition of this oxide layer is similar to that of the oxide inclusion in the steel, being comprised of SiO₂, CaO and Al₂O₃. As this layer apparently impedes the physical and chemical reactions that may otherwise take place between the tool and the steel chip, and, furthermore, apparently acting as a kind of lubricant, the tool life is exceedingly improved.
With a high-speed steel tool, however, such difference in tool life has hardly been noticeable in respect of the said three types of steels, and, furthermore no oxide layer has been noted to form on the tool face even when turning the specially deoxidized free-cutting steel.
The drill life was found to be remarkably improved and the work resistance was greatly lowered with increase in the sulfur content of the steel. This favorable effect of sulfur content has been more salient in the specially deoxidized free-cutting steel having an high oxygen content than in the case of ordinary steels.

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Machinability of Deoxidized Steel

Taiji ARAKI, Susumu HAMABATA

1971 Volume 57 Issue 13 Pages 2090-2099
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2090

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The machinability should be evaluated by the combination of cut steels and cutting tools. Tool life by turning with combinations of various deoxidized steels and various tools are studied.Si killed, Ca-Si killed, Si-Al killed, Ca-S:-Al killed constructional steels were selected.P20 type of sintered carbide and SKH 4 A type of high speed steel were tested as tools.
Non-metallic inclusions are different from each other corresponding to the killing process and affect the cutting process. The cutting process by the sintered carbide tool is distinguished from that by high speed steel tool.The sintered carbide being used, sometimes nonmetallic inclusion of Ca-silicate or Mn-silicate adheres on the surface of tool, works effectively and prolongs the tool life.Usually, it affects adversely the cutting process by high speed steel.Non-metallic inclusions of Al₂O₃ gives some bad effects on the both tools.Sulphide inclusion improves the life of high speed steel tool more than that of sintered carbide tool.

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Effects of Deoxidation on the Machinability of Resulphurized Steels in Machining with High Speed Steel Tool

Tatsu FUJITA, Yoshihiro YAMAGUCHI, Yasuyoshi HAGIHARA, Tsugio KANEDA, ...

1971 Volume 57 Issue 13 Pages 2100-2110
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2100

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Effects of deoxidation and chemical composition on the machinability based on tool life in machining low carbon resulphurized steels and medium carbon steels with high speed steel tool are investigated.
In turning low carbon resulphurized steels, core of rimmed steel has superior tool life characteristics, while rimmed layer has poor one due to its cleanliness. Mn-S killed steels with very low Si content, which are killed due to high Mn and high S contents, have good machinability uniformly from outer layer to core.Si deoxidation is very detrimental to the machinability. High oxygen content is favorable to the formation of round sulphides in Mn-S killed steels, and their machinability are improved with increasing ΣO content up to 0.026%. Sulphide shape substantially affects chip formation behavior and cutting temperature.The poor machinability of Si deoxidized resulphurized steels is due to formation of elongated sulphides and hard oxide particles.Tool life is well correlated to the cutting temperature and amount of hard particles such as SiO₂ and Al₂0₃ in steels.
In machining medium carbon steels with different S contents, deoxidation seems to have minor effects on their machinability.
Concerning with dependence of machinability on sulphide shape, the effects of cutting direction on the machinability of resulphurized steels are also discussed.

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On the Relationship between Machinability and Inclusion Morphology of Ca Bearing Free Machining Steels

Hiroyuki YAMADA, Shizuo YOSHIDA, Atuyoshi KIMURA, Koshi KATO, Teturo I ...

1971 Volume 57 Issue 13 Pages 2111-2127
Published: November 01, 1971
Released on J-STAGE: December 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2111

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The relationships-between machinability based on tool life and oxide inclusion morphology of calcium deoxidized Cr-Mo case hardening steels and carbon structural steels, melted by 2T arc furnace, were investigated.
The results are as follows:
1) In the case that the oxide inclusions in the calcium bearing free machining steels are A₂ type which are plastically deformed by hot rolling, the prolongation of tool life is ob. ained not only for cemented carbide tool but also high speed steel tool.
2) The oxide inclusions contributing to the formation of“Belag”on the cemented carbide tool face are those which soften or melt down at certain cutting temperature on the toal-chip contact surface.
3) Sulfur addition (0.07%S) to the calcium bearing free machining steels is effective for the chip breakability, but the effect is not clear for the tool life.

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On the Morphology of Non-metallic Inclusions and the Machinability of Calcium Deoxidized Steel

Akira KOYANAGI, Takashi SAKAJO, Toru KARASUDANI

1971 Volume 57 Issue 13 Pages 2128-2140
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2128

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Oxide inclusions in Ca-Si deoxydized steel were changed as; A₂ (Silicate)→B₂ (discontinious silicate)→C (globular oxide)↓
{Al addition→B (clustered Alumina) +C (globular oxide)(0.35-0.8kg/t)}
depending on the oxygen content before deoxydation process.
From the X-ray microprobe analysis, it was found that A₂ type inclusion had more then 55% SiO₂.
B₂ type inclusion had 45-55% SiO₂, and C type inclusion had up to 40% SiO₂.
Drillability and high speed tool life were improved by sulfur addition.
Effects of oxide inclusion on the carbide tool life were examined.
Crater wear of carbide tool were improved by A2 type oxide. When oxide inclusion changed to A₂→B₂→C→B type, frank wear of carbide tool with high cutting speed were improved in the order.

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The Effect of S, Se and Te on Machinability and Machined Surface Layer in High Carbon Chromium Bearing Steels

Kozo KISHI, Hiroshi EDA

1971 Volume 57 Issue 13 Pages 2141-2151
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2141

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The specimens used for this test were7steels containing free cutting additives;i.e., 0.010-0.141% S, 0.09% Se and 0.06% Te.
Tests of machinability and machined surface layer on various bearing steels were done with the orthogonal cutting and surface grinding operation.
The results obtained are as follows;
Bearing steels containing 0.141% S, 0.09% Se or0.06 % Te separately are favorable for the range in which damaged structure and residual stress distribution showed a remarkable change.And then plastic deformation of steel containing 0.06 % Te is relatively small compared to the other steels.
On the other hand, machinability in the orthogonal cutting and surface grinding showed a remarkable change for cutting ratio and surface roughness in cutting, and burn mark, chatter mark, surface roughness and chip formation in grinding.
For example, each of values of cutting ratio in steels containing 0.06% Te, 0.09%Se or 0.141 % Sseparately was nearly twice as great as that of0.010% S steel.The value of 0.06% Te steel was the largest.

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Effect of Non-metallic Inclusions on the Rusting of 17% Chromium Stainless Steel Exposed to Salt Spray Test

Noboru KINOSHITA, Nobuo OHASHI, Motohiko TAKEDA

1971 Volume 57 Issue 13 Pages 2152-2163
Published: November 01, 1971
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.57.13_2152

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On the bell-annealed hot rolled strip and the bright-annealed cold rolled strip of commercially arc-melted and processed 17% chromium stainless steel, the effects of aluminium content and composition of non-metallic inclusion on the susceptibility to rust corrosion during the 5% NaCl salt spray test have been investigated.
The optical and scanning electron microscopic observations and electron probe micro-analyses of the specimens after a few minutes of the salt spray test show that pitting corrosion initiates due to the dissolution of calcium-rich sulphides which are located as shells surrounding the aluminate inclusions. Iron dissolves from inner surface of a pit and deposits as ring-like rust around the pit.Segregations of calcium and sulphur are detected at this ring-like rust.
The proportion of the number of these water-soluble inclusions increases with the aluminium content of steel.

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