In order to elucidate the fundamental aspects of the sintering processes of self-fluxing sinters, the mineral formation processes of mixtures of iron ore and lime stone with or without coke were studied. After heating between 1200° and 1350°C the sinters were examined by microscopy, X-ray diffraction and EPMA.
The results indicated that the mineral formation processes of the systems were fundamentally the same as those of 80%Fe₂O₃ CaO-SiO₂ system reported earlier. They were as follows:
(1) Molten calcium ferrite was formed at the beginning.
(2) Gangue minerals dissolved into the melt.
(3) Iron oxides were precipitated. They were either or both of hematite and magnetite, depending on the oxygen potential or the SiO₂ content of the melt.
(4) At higher temperatures, solid iron oxides and a melt coexisted, and characteristic microstructure was formed during solidification depending on the basicity.
On the basis of the above results, the microstructures and the formation processes of self-fluxing sinters with various basicities were discussed.

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The interaction between solute atoms and radiation induced defects was studied by means of tensile test and transmission electron microscopy. The defects were produced by neutron irradiation at 473K to a fluence of 6.4×10²²n/m² (E_n>1MeV) and electron irradiation at 650kV electron microscope to a fluence of 7×10²⁵e/m².
Radiation hardening and radiation embrittlement occurred by neutron irradiation. The yield stress increased and the total elongation decreased with the increase of manganese content. Dislocation loops were observed in the iron but not detected in manganese alloys. Therefore, it will be considered that the defects would be trapped by manganese atoms and then formed complexes with carbon. Defects produced by electron irradiation were not observed by electron microscopy in the manganese alloys, however, after annealing above 598K the defect clusters, presumably interstitial type, appeared and grew. The annealing behaviors were similar for both the neutron and electron irradiated specimens.
The radiation hardening could be explained by the mechanism in which manganese atoms trap carbon and interstitial atoms during irradiation and then form fine complexes, which would act as the obstacles for dislocation motion.

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Annealing processes in low-carbon aluminium-killed steel sheets after 75% cold-rolling have been studied by means of vector analyses of the thermoelectric power vs. electrical conductivity plots on the basis of the postulates, that the gradient of the vector characteristic to dislocations is 500μv•μΩ•cm•deg^-1 in pure iron but decreases by trapping of carbon atoms, and that the gradient of the vector representing the cementite precipitation at 250°C is 310μV•μΩ•cm•deg^-1. It is speculated that a certain amount of carbon atoms is liberated from cementite and trapped by dislocations during cold rolling. The amount, which depends on the size and morphology of cementite particles, is correlated with the kinetics of recovery and recrystallization.

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Rates of sulfur transfer from the gas phase to liquid slaps in the presence of liquid iron under the reducing atmosphere were studied. In the present work, an Ar-H₂S gas mixture was introduced over slaps as CaO-SiO₂ and CaO-SiO₂ Al₂O₃ slaps at 1550°C.
Results obtained are summarized as follows:
(1) Although the sulfur transfer from the Ar-H₂S gas mixture to liquid slaps is practically independent of the presence of liquid iron, the rate of sulfur absorption of acidic slaps increases gradually as the reduction of silica in those slaps proceeds.
(2) When the slaps are acidic, it is observed that sulfur transfers into liquid iron through those slaps and then returns to slaps after the maximum concentrations are attained.
(3) The rate of silicon transfer from Slags to liquid iron increases with increasing sulfur absorption of slaps from gas phase, because the reaction of sulfur absorption of slaps accompanies the consumption of oxygen ions in those slaps.

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The crack morphology of the stress corrosion cracking of commercial 304-type austenitic stainless steel in boiling 42% magnesium chloride solution changes with the increase of the applied stress.
In this paper it was intended to attest that this transformation depends upon the stress intensity factor at the crack tip, and to inspect whether the crack propagation proceeds along a particular crystallographic orientation. The ratio of intergranular cracking to transgranular one was measured on the single notched specimens fractured under various loads such as 2940, 3920 and 5880N.
The relation between the crack morphology and the stress intensity factor at the crack tip was investigated, and the dependence of the crack propagation upon the crystallographic orientation was inspected by the etch pit method on the crack surface of the specimen fractured under the initial load, 2940N.
The following conclusions were obtained from this experiment: The crack morphology transformed remarkably from transgranular cracking to intergranular cracking with increasing applied stress or the stress at the crack tip, and the degree of transformation was closely connected with the stress intensity factor at the crack tip.
The transgranular cracking in the low stress region was likely to be formed by the crack growth following along <110> direction on {110} planes, and the facets formed on the crack surface due to this dependence of crack propagation upon crystallographic orientation.
These results indicate that this crack morphology was formed by the anodic dissolution of the sessile dislocation part and the tearing of the undissolved parts by stress.

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An Fe-16%Ni-4%Si alloy having a large hardenability due to a maraging mechanism was used to study the effect of microstructures present prior to aging upon the properties of tensile strength. In an attempt to obtain microduplex structures showing a good combination of strength and toughness, the present alloy was cold rolled by 80% at a martensitic state (i.e., marforming) after conventional solution treatment in the γ field, and then annealed at the temperatures in the α+γ two phase range followed by air cooling, and finally aged.
The marforming was found to increase both the tensile strength (σ_u) and the reduction of area (ψ) due to the formation of proper duplex structures. Large uniform elongation (ε_u) was observed after annealing at the temperatures around 570°C, and this was attributable to a transformation plasticity of precipitated austenite which was stabilized thermally. by partitioning of Ni. The strength, however, was rather low and σ_u=120kg/mm². When annealed at a temperature range between 600°C and 650°C (still in the two-phase range), the reverted austenite was transformed on cooling into martensite which was strengthened by agingproportionally to the martensite fraction; the resultant duplex (martensite+ferrite) structure had a strength of σ_u=158kg/mm², and a plasticity ofψ=27% and ε_u=1%, which were better than the combination, σ_u=132kg/mm², ψ=25% and ε_u=1% in the same alloy that was age-hardened conventionally without marforming and annealing.
The marforming had a dominant effect of reducing transgranular brittle fracture as well as intergranular fracture associated with preexisting coarse austenite grains.

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To investigate the effects of intercritical rolling, found beneficial in the laboratory-scale rolling tests, plain carbon steels were rolled by this technique in a hot strip mill. The results obtained are as follows:
(1) Both spiral-welded and electric-resistance-welded pipes made of intercritically rolled coils develop strengths of X52 grade and good notch toughness at low temperatures.
(2) Improved strength and notch toughness of intercritically rolled coils are attributable to grain refinement in the ferrite and pearlite transformed from the worked austenite, and to formation of substructures in the ferrite worked in the intercritical region.
(3) When compared with conventional rolling, intercritical rolling produces no unfavorable effects on steels, such as lowered strength and deteriorated notch toughness in weld zones.
(4) The texture of intercritically rolled material in the midthickness layer is that of cold rolling with strong fiber structures having <110> axis parallel to the rolling direction as its main component, but the mechanical properties of the pipes made of this material are excellent since they undergo less change during pipe forming and the planar anisotropy of yield strength decreases.
It has been concluded that intercritically rolled strip is suitable for structural steels such as those used for high-test line pipe where high yield point and good notch toughness are required.

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In recent years, the laser Raman microprobe technique has attracted the attention of many researchers as a new analytical technique for local application. This paper introduces the principle, function and features of the technique and discusses its applicability to the study of iron and steel, citing several examples of application. This technique is based on phenomenon, called the Roman scattering, which is caused when a sample is irradiated with a laser light focussed to the utmost. The advantage of this technique over conventional ones is that it is capable of obtaining the information about chemical species and atomic groups of molecules in local areas (-μm) through point, line or image (Raman image of specific wavenumber) analysis. Although this technique has not yet been applied widely in the study of iron and steel, the scope of its application will be greatly widened as a powerful tool in the elucidation of local defects, such as blisters, precibitates, inclusions and corrosion products.

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