The Amagasaki No. 1 Blast Furnace, Kobe Steel, Ltd., was blown out in the course of operation and dissected. Complete pictures for the profiles of worn linings in different zones, particularly in the tuyere zone, were obtained and mineralogical examinations of the refractories were made with particular attention to the behaviors of alkalis and zinc. Penetration of alkalis into the brick and formation of alkali aluminosilicate which would accompany the cracking and swelling are main causes of the wear of the refractories. The turning-up of the tip of tuyere would be due to the swelling of the tuyere fireclay brick.

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The effect of superposition of small repeating stress on the 100hr delayed failure strength, the stress under which no crack initiation occurs within 100hr, and on the incubation time (time to crack initiation) has been investigated using notched specimens of four kinds of steels (JIS: SKD61, SNCM8, SUS420J2, and 18Ni maraging steel) quenched and tempered at various temperatures.
For all the steels examined, the 100hr delayed failure strength were not varied by the superposition of repeating stress when the stress amplitude, σ_a, was 2.5kg/mm². When σ_a was larger than 5kg/mm², however, the 100hr delayed failure strength decreased with increase of σ_a, 18Ni maraging steel and SUS420J2 stainless steel with higher value of delayed failure strength under static stress revealed the smaller decrease of delayed failure strength under repeating stress than SKD61 and SNCM8 steels.

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In order to develop a series of austenitic manganese nonmagnetic steels, a systematic investigation has been made on the effects of chemical compositions including impurities and also heat treatments on the magnetic permeabilities, mechanical properties, machinabilities, and weldabilities.
The magnetic permeability depends on the austenite stability, that of strained specimen was expressed as linear function of Md temperature and the increase due to isothermal austenite decomposition was found to be suppressed by vanadium addition. A linear regression equation relating 0.2% proof stress to chemical composition indicated a great strengthening effect of vanadium comparable to that of carbon. Isothermal decomposition of austenite also lowers the Charpy impact toughness. It was found that the 0.7C-15Mn-1Ni steel was the optimum base composition. A modified grade of the base steel to possess both improved machinabilities and weldabilities was developed by lowering the phosphorus level and also adding free-machining elements as calcium and sulfur.

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The solution property of MgO containing materials into the CaO-Fe₂O₃ system and the melting property of MgO containing sinter during reduction were investigated. The results obtained are summarized as follows:
(1) The formation of high viscosity silicate and magnetite prevents the homogenization of slag and therefore, Cr slag and Ni slag remain unslagged. The formation of dicalcium ferrite prevents the dissolution of periclase into the CaO-Fe₂O₃ system.
(2) During reduction unslagged MgO makes the shell of MgO-FeO solid solution with FeO in glassy silicate and its solution is negligibly low.
(3) For both normal sinter and pellet, all silicate minerals dissolve above about 1240°C.
(4) MgO addition in sinter is effective to decrease the slag quantity during reduction but the melting property of sinter is not so improved as that of pellet. The proper basicity for sinter and pellet is about 1.4.

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Effects of the addition of SiO₂ and Al₂O₃ to green and pre-heated hematite compacts on the expansion/contraction of the two compacts when reduced in a hydrogen atmosphere were studied by measuring changes in the electrical resistance and thermal expansion/contraction.
The results obtained are as follows:
(1) Green compacts are reduced faster than pre-heated compacts. The reduction of green compacts proceeds simultaneously at the inner parts as well as at the surfaces, while pre-heated compacts are reduced slowly in accordance with the core model where the reduction proceeds gradually from the outer to the inner parts.
(2) In case of green compacts, the smaller the oxide particle size is, the slower the reduction rate is and also the less the shrinkage due to reduction is.
(3) Cracking of green and pre-heated compacts containing foreign oxides is considered to be due mainly to the local stresses in compact matrix caused by the difference in shrinkage between the contained oxides of different sizes and, in some cases, to the so-called phase-separated structure.
(4) The electrical resistance is clearly related to expansion/contraction over 95% reduction in case of green compacts except the compact containing γ-alumina; in case of pre-heated compacts, over 90% reduction when silica is contained and over about 60% reduction when alumina is contained.

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The melting rate of iron oxide pellets into iron melt and the reduction rate of pellets by carbon in iron melt were obtained by measuring the evolution rate of CO gas. The pellets were made from iron oxide powder by pressing and sintering and were not crushed into pieces when added onto the iron melt. The effects of the iron oxide phase, the oxide additives in pellets, and the temperature and the carbon content of iron melts on the melting and the reduction rates were investigated. The following results were obtained:
(1)It has been found that the heat transfer was not the rate-determining step for the two rates. It is considered that the carbon diffusion in a boundary layer on the iron melt surface could be the rate-determining step.
(2) The total reduction rate was constant for reduction degrees from about 20% to about 70%, where solid iron oxides were reduced by carbon dissolved in iron melt.
(3) The apparent activation energy of the melting of pellets into the carbon saturated iron melt was 35 for Fe₂O₃; 18 and 41 for Fe₃O₄ above and below 1470°C, respectively; 44 and 79kcal/mol for FeO above and below 1470°C, respectively.
(4) The melting rate of Fe₂O₃, Fe₃O₄ and FeO pellets into the iron melt at 1570°C was proportional to C^0.57, C^0.45 and C^0.42 respectively, where C denotes the weight percentage of carbon in an iron melt. The minimum amount of CO gas evolved was obtained at about 2%C.

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A complete stress-strain curve for brittle materials cannot be obtained with conventional testing machines because of their low stiffness and difficulty in strain-control. In this paper, the deformation and failure behavior of refractories for use in blast furnace under strain-controlled uniaxial compression measured with a stiff testing machine is discussed.
It was found that the refractories retain some strength and still have appreciable elasticity even after the maximum stress is reached. Fireclay brick shows anisotropy with regard to the stress-strain curve. It has good deformability and superior resistance to failure under thermal stress applied parallel to the direction of press forming. Carbon brick fractures with little deformation after the maximum stress is applied. At temperatures above 800°C, fireclay brick exhibits visco-elastic behavior, which is substantially explained by the Burgers model.

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Conventional roll forming processes for electric-resistance-welded (ERW) pipes are outlined with respect to roll contours, stand arrangements and deformation strains during forming. The developmental history and features of a new process (VRF process) for forming ERW pipes by constraining the strip edges with undriven vertical rolls are described. The equipment characteristics, fundamental forming characteristics and forming load characteristics of the new process are compared with those of the conventional ER W pipe roll forming processes. Neutral line constant as pass line and uniform displacement distribution as forming distribution are found to be the optimum combination for the VRF process. The results of the present study show that this process can reduce edge stretch and forming energy, and is expected to save roll, equipment and energy costs when put to commercial use. The dimensional tolerances of pipe products manufactured in preliminary commercial production experiments are also described.

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