Tetsu-to-Hagane

Some Essential Issues Concerning Japanese Steel Industry

Tadashi IKEDA

1983 Volume 69 Issue 11 Pages 1367-1371
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1367

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Microstructural Studies on the Properties of Steels for Developing Advanced Performance

Toru ARAKI

1983 Volume 69 Issue 11 Pages 1372-1381
Published: September 01, 1983
Released on J-STAGE: February 15, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1372

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Aluminum Blast Furnace Feasibility and R & D Policy

Masayuki DOKIYA, Harumi YOKOKAWA

1983 Volume 69 Issue 11 Pages 1382-1387
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1382

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Corrosion and Adhesion Failure of Painted Steel Sheet

Shigeyoshi MAEDA

1983 Volume 69 Issue 11 Pages 1388-1397
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1388

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Characterization and Control of Steel Surfaces

-(I) Structure and Properties-

Yoshihiro HISAMATSU

1983 Volume 69 Issue 11 Pages 1398-1408
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1398

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Reduction Process of CaO-Fe₂O₃ Binary Calcium Ferrite and Resultant Expansion

Noboru TAGUCHI, Takaho OTOMO, Kou TASAKA

1983 Volume 69 Issue 11 Pages 1409-1416
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1409

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The reduction process of artificial 2CaO·Fe₂O₃, CaO·Fe₂O₃ and CaO·2Fe₂O₃ by CO-CO₂ mixed gas and the accompanied expansion have been studied in connection with the behaviour during reduction of lime self-fluxing sinter. The main results obtained are as follows :
(1) A scheme of reduction process of CaO·2Fe₂O₃, CaO·Fe₂O₃ and 2CaO·Fe₂O₃ at 800°, 900°, 1 000 °C (solid line) and 550°C (chain line) was found as follows :
(2) At 800°, 900°, and 1 000°C, the expansion (about 0.8%) in the reduction of CaO·2Fe₂O₃ and CaO·Fe₂O₃ occurred up to formation of 2CaO·Fe₂O₃, Ca0·3FeO.Fe₂O₃ and Fe_xO, and the expansion in the case of 2CaO·Fe₂O₃ was only small.
(3) At 550°C, the abrupt expansion (about 4%) in the reduction of CaO·Fe₂O₃ may be caused by formation of metallic iron and carbon deposition incidental to its formation, and that the expansion in the reduction of CaO·2Fe₂O₃ occurred in two steps; the first step expansion (about 0.8%) occurred up to formation of Fe₃O₄ and the second abrupt expansion may be caused by the same reason as in CaO·Fe₂O₃.
(4) At each temperature, the expansion of Fe₂O₃ was the highest and the expansion of calcium ferrite was much less than Fe₂O₃, and the expansion of binary calcium ferrite increased with increasing Fe₂O₃ content in ferrite.

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Thermal Conductivities of Slags for Ironmaking and Steelmaking

Kazuhiro NAGATA, Masahiro SUSA, Kazuhiro S GOTO

1983 Volume 69 Issue 11 Pages 1417-1424
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1417

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Thermal conductivities of synthetic slags and a slag sample taken from a blast furnace in normal operation have been measured by the hot wire method. The synthetic slags are composed of CaO-SiO₂-Al₂O₃, CaO-SiO₂-Fe₂O₃, Na₂O-SiO₂, CaF₂, and CaF₂-CaO-SiO₂-Al₂O₃. The measuring temperature was widely changed from 100 to 1 500°C. In the temperature range lower than 1 000°C, the thermal conductivities of solid slags increased from 1.0 to 2.0 W/m·K with increasing temperature, and above 1 000 °C, they rapidly decreased to values of between 0.5 and 0.1 W/m·K in liquid state. The thermal conductivity of CaF₂, which crystalizes in solid state, decreased monotonously with increasing temperature. The thermal conductivities of slags at high temperatures were empirically expressed as λ=(a/T)exp(-bT), where a and b are constants and T is absolute temperature. The thermal conductivities of liquid slags were about one tenth of those of the common refractories at high temperature.

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Effect of Sulfur on the Formation of Blowholes during Solidification of an Fe-C Alloy

Eiichi KATO, Atsushi HIRANO

1983 Volume 69 Issue 11 Pages 1425-1432
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1425

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Experiments on the formation of N₂ blowholes and CO blowholes in unidirectionally solidified Fe-C alloy with various sulfur concentrations are made, and the experimental results are discussed on the basis of the interdendritic segregation model.
Sulfur enhnaces the formation of bubbles and retards the detachment of bubbles from solid-liquid interface. Consequently, sulfur enhances the formation of blowholes. This characteristic of sulfur is shown remarkably in the formation of N₂ blowholes. This effect of sulfur is attributed to that sulfur is surface active; the surface tension of iron is reduced by sulfur and the formation of bubbles in interdendritic liquid becomes easy, and the rate of the gas evolution from iron is decreased by the adsorption of sulfur on the surface of iron.
In addition, the effect of stirring of liquid phase by high frequency induction on the formation of blowholes is studied. Stirring of liquid phase depresses the formation of blowholes especially that of N₂ blowholes. This effect of stirring is attributed to the lag of enrichment of the solute in interdendritic liquid.

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Phenomena of Solidification and Macrosegregation in the Unidirectionally Solidified Ingots

Masayuki NAKADA, Toru KITAGAWA, Kozo YANO, Shinjo ASANO, Akira MASUI, ...

1983 Volume 69 Issue 11 Pages 1433-1439
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1433

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The solidification characteristics and the macrosegregation of the unidirectionally solidified ingots weighing 2 70t have been examined.
It has been found that neither secondary shrinkage pipes nor V-segregation exist in the ingots and inverse V-segregation exist only in the restricted area near the side wall.
It has been proved that the unidirectionally solidified ingots show the superior nature with respect to the soundness and homogeneity and are very suitable for production of heavy gauge plates by rolling without forging. The reason for the above is supposed that the liquid steel can be fed to the solidification front easily until the final stage of solidification.
The formation mechanism of positive segregation layer beneath the top surface of the ingot has been investigated. It is found that this is formed as the result of inverse V-segregation formation near the mold wall. Based on the formation mechanism, several operational factors to minimize the positive segregation have been pointed out.

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Recrystallization Behaviour of 17 Cr Ferritic Stainless Steel during Hot Rolling

Hirofumi YOSHIMURA, Mitsuo ISHII

1983 Volume 69 Issue 11 Pages 1440-1447
Published: September 01, 1983
Released on J-STAGE: February 16, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1440

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To investigate the recrystallization behaviour of a 17 Cr ferritic stainless steel during hot rolling, wedge shaped specimens taken from continious casting slab were hot rolled at temperatures from 1 173 K to 1 453 K in single pass manner, and then hardness test and optical microscopic observation were conducted. The results are as follows.
At relatively lower heating temperatures near 1 173 K, deformation structure having many deformation bands forms especially in the vicinity of austenite phases that are isolatedly scattered in the initial ferrite grains. At higher rolling reduction, much deformation bands are introduced. At heating temperatures near 1 273 K, deformation structure changes into partial recrystallization structure with increasing rolling reduction. At relatively higher heating temperatures, recovery structure which contains many fine subboundaries is attained. Therefore the nose in recrystallization behavior exists at near 1 273 K.
In the recrystallization region, recrystallization is accelerated with increasing rolling reduction, and consequently hardness of hot rolled specimens decreases at higher rolling reduction. However in the recovery region accompanied with sub-boundaries hardness increases with increasing rolling reduction.
From the above results and discussion in mechanism of microstructural changes under restoration process it is concluded that recrystallization structure is statically formed after hot rolling and recovery structure is dynamically formed in hot rolling process.

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Effect of Cold Work and Volume Fraction of Ferrite on Corrosion Resistance of (α-γ) Duplex Stainless Steel

Kikuo TAKIZAWA, Yasuhiko SHIMIZU, Yoshihiro HIGUCHI, Imao TAMURA

1983 Volume 69 Issue 11 Pages 1448-1455
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1448

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The effects of cold working and volume fraction of ferrite on corrosion behavior of the active and pitting region of duplex stainless steel have been studied in sulfuric acid and chloride media. The main results obtained are summarized as follows :
(1) In boiling 5% H₂SO₄ solution, the corrosion loss and the critical current density for passivation of specimens decreased with the progress of working and the increase in α content.
In all of the specimens, the preferential dissolution phase in the active region was γ, but the dissolution of γ was retarded by working.
(2) In boiling 5% H₂SO₄+NaCl solution, the corrosion loss, in not more than 0.1% NaCl, was less in specimens containing much α and undergoing much degree of working. In case of 1% NaCl, however, it was more in those specimens. The preferential dissolution phase in the active region, on additions of 1% NaCl, changed by working and α content and it changed obviously with potential in specimen containing the least α.
(3) In 3% NaC1 solution at 30°C, it was found that pitting potentials had α tendency to become noble with the increase in α content, the effect of working on that, however, was not obvious. In all of the specimens, the pitts produced with anodic polarization occurred in γ and grew preferentially into γ.

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Mechanical Properties and Weldability of High Strength Stainless Steel Bearing 0.03% or Less Carbon for Railroad Vehicles

Teruo TANAKA, Keiji OSAKI, Haruki WATANABE, Kazuo HOSHINO

1983 Volume 69 Issue 11 Pages 1456-1462
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1456

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The effects of alloying elements, volume fraction of deformation-induced martensite and rolling reduction on the mechanical properties of Type 301 stainless steels bearing 0.03% or less carbon have been investigated, and product properties of this Type 301L are also shown.
1) Tensile strength strongly depended on the volume fraction of deformation-induced martensite and tensile strength decreased with increasing Ni_eq., where Ni_eq.=Ni(%) +0.35Si(%) +0.5Mn(%) +0.65Cr (%) +12.6(C+N)(%). Steels having a constant Ni_eq. showed higher tensile strength by increasing N.
2) Proof stress of as-annealed and 20%-rolled materials was little affected by Ni_eq. and increased with increasing N content.
3) Elongation was little affected by N content, and it strongly depended on Ni_eq. As N is one of the factors in Ni_eq., N has an influence on elongation through Ni_eq.
4) The mechanical properties of all the products, from LT to HT tempered ones, were confirmed to meet the typical specification for the railroad vehicles.
5) Mechanical properties of Type 301L welded joints were equal to those of Type 301M bearing 0.06% carbon.
6) In the case that metastable austenite stainless steels were cold-rolled, welding current required to form the nugget where diameter was 4 mm decreased, because specific resistance increased with increment of deformation-induced martensite by cold-rolling.
7) Resistance of Type 301L to intergranular stress corrosion cracking and intergranular corrosion was superior to that of Type 301M.

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Environmental Factors that Influence the Susceptibility of Line Pipe Steels to External Stress Corrosion Cracking

Komei KASAHARA, Taisaku SATO

1983 Volume 69 Issue 11 Pages 1463-1470
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1463

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Stress corrosion cracking (SCC) susceptibility of X60 line pipe steel was evaluated by means of the slow strain rate technique (SSRT) as well as the static load technique (SLT) in four environments, i.e., NaOH, Na₂CO₃-NaHCO₃, Ca(NO₃)₂ and SO₂, that were found potentially to cause SCC by the potentiodynamic polarization screening tests on 25 chemical species present in the soil. The results obtained are summarized as follows :
1) SCC in NaOH could be produced at temperatures above 40°C, at stresses above 30 kg/mm² and at potentials between -880 and -1230 mV vs. Cu-CuSO₄.
2) SCC in Na₂CO₃-NaHCO₃could be produced above 15°C, above 42 kg/mm² and between -650 and -875 mV.
3) SCC in Ca(NO₃)₂ could be produced above 30°C, above 5 kg/mm² and between +1 120 and -480 mV.
4) The minimum concentration required to produce SCC was 5% for NaOH and 0.5 N for Na₂CO₃-NaHCO₃.
5) A saturated SO₂ solution was found to promote transgranular stress corrosion cracking in X60 line pipe steel at ambient temperature.
6) The SCC potential region indicated by SSRT in terms of reduction in area was in good agreement with that by SLT in terms of time to failure.

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Study on Material Factors that Influence the Susceptibility of Line Pipe Steels to External Stress Corrosion Cracking

Komei KASAHARA, Haruhiko ADACHI

1983 Volume 69 Issue 11 Pages 1471-1478
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1471

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Material factors that might influence the susceptibility of buried line pipe steels to stress corrosion cracking (SCC) were studied by means of the slow strain rate technique (SSRT) of SCC tests in carbonate-bicarbonate (CO₃) and caustic alkali (OH) solutions which had been identified as the environments that could produce SCC on buried steel pipelines. The results obtained are summarized as follows :
1) Possible SCC potential ranges for as-received line pipe steels in OH and CO, were -880 to -1230 mV and -650 to -875 mV vs. Cu-CuSO₄, respectively, and were independent of types of steel.
2) SCC susceptibility of every line pipe steel changed in a decreasing order of STPY 41> X42> X65CR> X6OCR> X65QT.
3) Effect of rolling direction on the SCC susceptibility was weld metal>C>L for STPY 41, while C>L>weld metal for the rests, both in a decreasing order of susceptibility.
4) Effect of heat treatment on the SCC susceptibility was water quenched>annealed>as-received> quenched and tempered, in a decreasing order of susceptibility.
5) Activation energies for the growth of stress corrosion cracks in CO₃, and OH were almost the same with those of crack-tip dissolution, which lended strong support to the suggestion that the controlling process in SCC of line pipe steels in CO₃ and OH was crack-tip dissolution.

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Fatigue Crack Growth Rates and Their Thresholds of High Strength Steels in Sea Water at the Zinc Potential

Masae SUMITA, Norio MARUYAMA, Iku UCHIYAMA

1983 Volume 69 Issue 11 Pages 1479-1486
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1479

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Fatigue crack growth rates, da/dN, and their thresholds, ΔK_th, have been examined in sea water at zinc potential, sea water, and air, using seven kinds of 102-165 kgf/mm² grade steels at the frequency of 0.167 Hz and 20 Hz and at the stress ratio of 0.10 and 0.70. The following results are mainly obtained.
1) At the zinc potential, the effect of corrosion control against fatigue crack growth of 100-120 kgf/mm² grade steels is observed to be beneficial when ΔK <55-60 kgf/mm³/² at the stress ratio of 0.10 and at the frequency of 0.167 Hz. The value of ΔK, however, decreases to 30 kgf/mm³/² for the 165 kgf/mm² steel.
2) At the zinc potential, the effect of hydrogen on da/dN-ΔK curves is classified into two; one is that for the plateau behavior (intergranular failure) which is sensitive to temper brittleness and the other is for the threshold ΔK_th (trangranular failure) which is insensitive to that.
3) The value of ΔK_th gradually decreases with increase of yield strength. At the zinc potential, the value decreases catastrophically at the yield strength of more than about 120 kgf/mm² due to hydrogen.

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Effect of Rolling Contact Stress and Carbon Content in Matrix on the Formation of Platelike Carbides during Rolling Contact Fatigue of Bearing Steel

Kazuichi TSUBOTA

1983 Volume 69 Issue 11 Pages 1487-1493
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1487

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Platelike carbides form immediately under flakings during rolling fatigue tests in the ball/washer thrust type fatigue testing rig.
Carbon content in the matrix and shear stress in the thrust type test specimens were studied in this report which influence the formation of the platelike carbides closely related to bearing life.
It has been revealed for the formation of the platelike carbides that carbon content of approx. 0.25% and a hertzian stress of approx. 60 kgf/mm² are necessary and also a minimum required stress cycle varies depending on the product of these two factors (carbon content × shear stress). It has also been confirmed that the same critical conditions can apply to industrial bearings to produce the platelike carbides.
Another investigation made in relation to diffusion frequency of carbon and nitrogen at 120-deg. has shown that it is difficult for the platelike carbides to form when the diffusion frequency of these elements gets too large.
We have made an overall conclusion from the above mentioned results together with those obtained in the previous experiments that oxide inclusions as sources of stress concentration must be reduced down to as small an amount as possible and carbon content had better be lowered in the matrix to extend bearing life as long as a proper hardness is maintained.

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Deboronization in Boron Steel and a Model for Its Calculation

Tsuyoshi INOUE, Yoshitaka OCHIDA, Kunio TSUJI

1983 Volume 69 Issue 11 Pages 1494-1501
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1494

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Deboronization behavior during austenitizing of 0.2%C-0.85%Mn boron-treated steels was investigated in the various atmospheres. A considerable amount of boron removal was observed during the heat treatment in the air, and neither an atmosphere of argon nor a nickel-plating on metal surfaces had detectable effect in preventing this phenomenon. Deboronization could be eliminated only in the vacuum of 10^-4 Torr with a zirconium oxygen getter.
Boron concentration profiles after deboronization occasionally showed some anormalous appearances which were unexplainable by a diffusion control mechanism. One was a two-step fashion in a boron concentration profile and the other was an enhancement of deboronization at a certain temperature range. The latter, for instance, involved a lower residual boron concentration at 850°C rather than at 950°C.
A probable model for deboronization kinetics was discussed taking a dissolution of fixed boron as precipitates together with a diffusion of free boron into consideration. In addition, the effect of formation of ferrite owing to a simultaneous occurrence of decarburization was also taken into consideration. A finite-difference method was applied to the calculation of boron profile and it was shown that the above-mentioned anormalous phenomena were predictable.

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Relation between Carbide Precipitation and Toughness in 13Cr-3.8Ni Cast Steels

Yoshitaka IWABUCHI, Tomoo TAKENOUCHI

1983 Volume 69 Issue 11 Pages 1502-1509
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1502

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Relation between toughness degradation and carbide precipitation of 13Cr-3.8Ni cast steel has been studied experimentally and theoretically. The results are summarized as follows:
(1) Chromium carbide (M₂₃C₆) precipitated at prior austenite grain boundary in austenite region deteriorates the toughness to give mosaic-like intergranular failure.
(2) Notch toughness, FATT (°C), is a function of both carbon content, C (wt %), and cooling rate from 950°C, R (°C/h), and the following relation is obtained. FATT=3119·C-45 log R-13
(3) The rate-determining stage for the carbide precipitation is considered to be the formation of carbide.
(4) Reducing silicon content and increasing molybdenum content improve toughness as the result of retarding M₂₃C₆ precipitation along grain boundaries.

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On-Line Analyzer for the Concentration of Ni-Zn Alloy Plating Bath

Nobukatsu FUJINO, Yoshiro MATSUMOTO, Atsuyoshi SHIBUYA, Hideyoku NAKAH ...

1983 Volume 69 Issue 11 Pages 1510-1517
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1510

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Ni-Zn electroplated steel shows good corrosion resistance. It is important in the production of the electroplated steel to control the concentration of Ni²⁺ and Zn²⁺ in plating bath. An on-line analysis instrument by fluorescent X-ray analysis was developed for the process control.
(1) The analyzer consists of sampling-line and X-ray analysis instrument. The plating solution is fed to the X-ray analysis instrument through sampling-line from plating trays. These operations are done fully automatically.
(2) Fluorescent X-ray analysis system with energy dispersive method is used. It is necessary to correct the concentration of SO₄^2- and Fe²⁺ in determination of the concentration of Ni²⁺ and Zn²⁺. Measuring of fluorescent X-ray of S is easy in the air by the analysis system.
(3) For X-ray source, W target is used for excitation of Ni, Zn, and Fe fluorescent X-ray, and Cr target for S fluorescent X-ray, respectively.
(4) The analytical accuracy in on-line analysis was 0.77 g/l and 0.48 g/l for Ni²⁺ and Zn²⁺, respectively. The time required for one cycle analysis is eight minutes.
(5) This analyzer has been running for about two years without any trouble.

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[title in Japanese]

[in Japanese], [in Japanese]

1983 Volume 69 Issue 11 Pages 1518-1520
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1518

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[title in Japanese]

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

1983 Volume 69 Issue 11 Pages 1527-1529
Published: September 01, 1983
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.69.11_1527

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