Caking property is one of the most meaningful indices for the evaluation of coking coal, and is a basis for the coking mechanism analysis. The index given by the Audibert-Arnu dilatometer widely employed at present is re-evaluated in this paper.
The results suggest that present indices of contraction and dilatation have little physical meaning, and are not suitable for the absolute evaluation of the caking property of coals; An index for a true dilatation is newly proposed. This true dilatation index (D_T) is defined as the ratio of the apparent coal volume after dilatation (V_D) to that before dilatation (V_C) and expressed as, D_T=100(V_D-V_C)/V_C.
It was confirmed that this index was not affected by test conditions, and was suitable for the absolute evaluation of caking coal with less deviation. Furthermore, the effects of coal size and heating rate are quantitatively evaluated by the true dilatation index.

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Research on the coke strength has recently been carried out treating the coke as a porous material and a new progress is made in the essential evaluation of coke strength. Previous researches have, however, discussed mainly the effects of porosity and/or distribution of pores on the strength and little has been studied on the inherent strength which affects the coke strength.
In this research, a sieve opening for strength index applied to the microstrength which evaluates the inherent strength was investigated. The micro-strength with a smaller sieve opening was found to be a reasonable index for the inherent strength of coke.
It was confirmed that the tensile strength is estimated by porosity and micro-strength. The JIS drum strength which is usually used in industrial plant is also estimated from the porosity and the microstrength through the tensile strength. The results show that the coke strength is determined by the strength of porous material which depends on its porosity and inherent strength.

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The strength and reducibility of iron oxide briquettes were measured by the reduction-under-load technique and the loss-in-weight technique, respectively. The effects of sulphur and phosphorus pentoxide concentrations on the two properties were measured at elevated temperatures. Also, lime additions were made to briquettes containing either phosphorus pentoxide or iron sulphide. In general, phosphorus pentoxide and sulphur lowered both the strength and reducibility of the briquettes. Microscopic examination demonstrated that this is due to the formation of a slag phase with a low melting temperature range which decreases both the activity of the iron oxide and the porosity of the briquette. The addition of lime improved the strength of the briquettes containing either phosphorus pentoxide or sulphur.

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The crystallography of pearlite during the growth process in plain and alloy steels is investigated by transmission electron microscopy. The results show that the ferrite/cementite orientation is controlled by one of the two relations, viz., Pitsch or Bagaryatskii. The relation basically depends on the mechanism of nucleation either at “clean” austenite boundaries or on the pre-existing proeutectoid phase. The degeneration or spheroidization of cementite lamellae on reducing the transformation temperature is attributed to insufficient diffusion of carbon to maintain the lamellar shape. This process has no influence on the lattice relationship. In consistence with this conclusion, the interlamellar spacings are almost constant, despite the change in the pearlite morphology.

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Flange cracking of Drawn and Ironed can from tinplate is caused mainly by non-metallic inclusions in the end of the can. In this study, the chemical composition and the minimum size of non-metallic inclusions causing flange cracking in tinplate of Al-killed steel were examined. The chemical composition of non-metallic inclusions is composed of CaO-Al₂O₃ and the minimum size is 5μm in thickness and 50μm in width. Countermeasures for reducing inclusions were taken in the continuous casting process, and the tinplate quality was inspected by a magnetic inclusion detector, thus leading to a reduction in the flange cracking rate of Drawn and Ironed cans.

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A new approach is shown to predict coke strength (DI³⁰₁₅) from coal quality and operating conditions of a coke oven. Theoretical consideration of coking process and DI³⁰₁₅ shows that (1) tensile strength of semi-coke and thermal stress generated in semi-coke are important factors affecting DI³⁰₁₅ and (2) each factor is expressed by petrographical parameters obtained from fluidity and volatile matter of coal, crushing degree of the charge, flue temperature in a coke oven and heterogeneity of the charge which is defined mathematically.
An equation for predicting DI³⁰₁₅ is derived in a general form based upon the above consideration. For practical purposes, each coefficient in the equation is determined by data analysis. Because of its accuracy and simplicity, this equation is being utilized satisfactorily in operation of coke ovens at works.

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The tests of rubbing wear against hardened 0.45%C-steel and 316-type austenitic stainless steel were carried out in liquid N₂. Specimens used are (a) 20%Cr-(Fe, Co, Ni) solid solution alloys, (b) age-hardenable Nimonic 80A and Nimonic 100 alloys, and (c) low-Cr martensitic steels with and without carbide dispersion, whose martensite matrixes were controlled to have about 0.45% C. The rolling contact fatigue in liq. N₂ of these low-Cr steels were also investigated. The results obtained are as follows.
(1) The harder the solid solution is the fewer the wear-loss is. When the difference in hardness between the coupled specimens is large, the softer material adheres on the surface of the harder specimen, and then the coefficient of friction is very large.
(2) Age-hardening increases the wear proof of the alloy.
(3) The rubbing pair of matensitic steels is abrasively worn. The wear is suppressed by carbide dispersion, but the effect of the amount of carbide on wear is not so distinct. The rolling contact fatigue strength is increased by carbide dispersion.
(4) It is considered roughly that the soft and ductile materials are adhesively worn, tough materials are worn by delamination process, and the hard and brittle materials are abrasively worn. However, multiple processes proceed simultaneously, and the contribution of each process changes with the wearing conditions. Therefore, the relation between hardness and wear is sometimes complicated.

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Steel intended for use as the hull materials of deep submergible vehicles has been developed. The target properties of the steel were minimum yield strength of 900 MPa and high toughness.
The primary research was conducted on several steels containing a range from 2.5 to 5% Ni with the emphasis on mechanical properties, heat treating characteristics and weldability. The optimum chemical composition of steel having the above-mentioned properties has been formed to be 0.09C-5Ni-0.5Cr-0.5Mo-0.05V with minimal impurities, especially, low sulfur content. Production heats of this steel were conducted. Slab was made by electroslag remelting process for having ultra low impurities and super cleanliness. Plates of quenched and tempered steel of 65mm in thickness exhibited yield strength having a range from 931 to 960 MPa, and Charpy V-notch shelf energy absorption having a range from 172 to 209J.
According to this good quality, this steel plate was applied for the hull material of deep submergible vehicle (“Shinkai 2000”) operating in seas of 2000m depth.

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Transmission Kossel technique has been applied in an attempt to elucidate the origin of the potential nuclei of the celebrated (110)[001] secondary grains in the high induction grain oriented silicon steel. The (110)[001] secondary recrystallization nuclei, which are inherited by the structure memory from the original hot-rolled texture, are not the recrystallized grains in the vicinity of the steel surface of the hot-rolled steel, but the polygonized (110)[001] grains elongated toward the rolling direction at about 1/10 depth from the steel surface. The polygonized (110)[001] grain consists of several matrix bands containing the transition band and normally gives the line diffusing TK patterns. There are the highly oriented (110) [001] areas with the line sharpening TK patterns inside the polygonized (110)[001] grains, by which they appear to be guarded. The highly oriented (110)[001] areas are compatible with the colonies of the large primary recrystallized (110)[001] grains inherited even after the subsequent alternating operations of the cold rolling and the recrystallization annealing. It is considered that the potential nuclei of (110)[001] secondary grains will generate from the highly oriented (110)[001] areas, the preferential formation of which is indispensable for the development of the celebrated (110)[001] secondary grains during the secondary recrystallization annealing.

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Five major steel companies in Japan organized a committee in 1978 for investigation of shear fracture of pipelines, whose pipes are large diameter and high pressure resistant API 5LX X70 grade made by UOE Process. The main task of this committee was planning and execution of full scale burst tests for finding appropriate evaluation methods of characteristics for arresting the propagation of shear cracks. Since 1978 five full scale burst tests have been completed and the test results were described together with analysis. This paper is a kind of interim report, but the committee mentioned to a few outstanding conclusions relating to the effects of separation against fracture and critical energy values for arresting the crack propagation.

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