With respect to Goa hematite ores and Larap magnetite ores as raw materials, the influence of air flow, coke content and moisture content on the temperature distribution of the sintering bed were studied with a small sintering pan.
The results obtained were as follows:
(1) The air flow had an influence on the combustion rate of coke, moving rates of sintering zone and of the cooling zone, and thereby the temperature distribution of the sintering bed was largely varied.
(2) The coke content had an influence on the moving rate of the sintering zone and maximum bed temperature. When the coke content was higher than the optimum, the sintering zone tended to be broadened, yet the maximum bed temperature was little affected. At lower coke content, however, the maximum bed temperature was considerably decreased.
(3) The shape of the temperature-time curve was influenced by the moisture content, but the maximum bed temperature was little affected. The lower the moisture content, the broader the sintering zone and the cooling rate.

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Concerning the influences of sulphur in bunker C-oil the authers made an actual operating test with the continuous ingot-reheating furnace fired by an oil of high sulphur contents.
The results obtained were as follows:
(1) It produced more scale than by the use of an oil of low-sulphur contents.
(2) Scale on ingot surfaces became sticky.
(3) In the stronger oxidizing atmosphere of the furnace the scale on ingots was as much produced as in the oxidizing atmosphere without SO₂, and did not become sticky.
These phenomena abovementioned depended no doubt upon several conditions, such as a character of reheating furnaces, draught schedule of rolling pass, etc.
But it was able to remove these phenomena from actual working by controlling the atmosphere of the furnace.

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Under the impact bending load, an investigation was made on the change of the transition temperatures and fracture modes of the strained and strain-aged specimens, which were of a low-carbon killed steel containing 0·17%G. In this experiment, as described in the previous paper (Tetsu-to-Hagané, Vol. 46 (1960) p. 140), a miniature Charpy impact testing machine, being of 2kg-m capacity, was used and the load acting on the specimen was measured by the use of piezo-electricity of quartz crystals and a cathode-ray oscillograph.
The specimens were stretched by 3% and 10%, in static tension after the annealing at 920°C for 1 hour in vacuum. They were strain-aged at room temperature, 100°C and 200°C for various durations.
A new transition temperature, which was the highest testing temperature at which the marked propagation of a crack appeared, was defined in the previous paper. This transition temperature was very sensitive to the internal structures of the specimens. This definition was used also in this report.
The results in this investigation were summarized as follows:
(1) The strain-aging for 3 to 100 days at room temperature after the stretching of 3% and 10% did not change the transition temperature showing 25°C. The transition temperature for the 3%-stretched specimen aged at 100°C for 120 minuites and that for the 10%-stretched one aged at 100°C for 60 minuites remained to be 25°C. On the other hand, both the 3%-stretched specimen aged at 200°C for 60 minuites and the 10%-stretched one aged at 100°C for 120 minuites had the transition temperature of 40°C, which was 15°C higher than that for the other specimens.
(2) The absorbed energy vs. testing temperature curves for the specimens stretched 10%, and for the strain-aged ones were not decreased gradually with the testing temperature but decreased abruptly at two temperatures and there appeared a horizontal part, where the load-time curve of type III was recorded. This phenomenon, however, was not observed so much clearly with the 3%-stretched specimens and with the strain-aged ones.
(3) The more cold-worked the specimen was, the more steeply decreased the load acting on the specimen after the maximum load was reached.
The brittleness introduced by the cold working seemed to be different from that introduced by the quench-aging and strain-aging. The aging raised the transition temperature but the cold working did not raise it.

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Vacuum-melted steels are now going to be in practical use, and for bearing steel, which is to be produced in large scale, by vacuum arc melting method (the so-called Cons-el Arc melting method) should be more suitable rather than vacuum induction-melting method.
Therefore, the research for the material characteristics of Cons-el Arc melted bearing steel was conducted according to the inspection specification of Japan Bearing Society compared with the air-melted one.
As the results, it was found that the Cons-el Arc melted steel was much superior to the other in the macro-structure, compressive breaking strength, surface defects and so on.

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Chemical and X-ray analyses were carried out on carbides, isolated electrolytically from the as-annealed, as-quenched and as-tempered structures of chromium-base hot-working tool steels.
Carbides found in the as-annealed structures are M₂₃C₆, M₆C and MC, similarly to the carbides in tungsten-base hot-working tool steels. M₇C₃ and ξ carbide expected from the equilibrium diagrams for Fe-C-Cr and Fe-C-Mo systems were not observed in the as-annealed structures. Carbide reactions during tempering are complicated, but are regarded as the combination of four sequences, which proceed separately in chromium, molybdenum, vanadium and tungsten steels; that is (i) M₃C→M₇C₃→M₂₃C₆, (ii) M₃C→Mo₂C→M₆C, (iii) M₃C→MC, and (iv) M₃C→W₂C→M₆C+M₂₃C₆.
The rate of the carbide reactions taking place towards equilibrium during tempering were very slow, owing to the low mobility of molybdenum atoms.

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This report deals with a study on the effects of tempering time and repeated tempering at 575°C for carbides in low-W high speed steels.
The carbides were isolated electrolytically from specimens of several heat-treated high speed steels. Chemical composition and crystalline structure of the isolated carbides were determined by chemical analysis and X-ray diffraction, and the shape of the cabides were observed by electron microscopy. The results were obtaind as follows:
(1) The amount of precipitated carbides was increased gradually with progress of tempering time, but the amount of precipitated carbides during tempering at 575°C×100h were less than at 650°C×1h. The carbides in the steel on a short-time tempering were composed of M₆C and MC types, while M₂₃C₆ carbide appeared in the steel of tempering at more than 50 hours.
(2) On the repeated tempering at 575°C, the amount of carbides was increased, especially on twice-repeated tempering suddenly. The carbides in the steel on repeated tempering at 575°C were precipitated as much as those in the steel on continuous tempering of 10-50 hours at the same temperature. Presumably it should promote the precipitation of carbides during repeated tempering.

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This study was carried out to clarify the effect of cold working and “hot-cold” working on the heat-resisting properties of 316L 17Cr-12Ni-2Mo steels and low-Ni Timken 16Cr-15Ni-6Mo (-7·5Mn) type alloys. Main results obtained were as follows:
(1) With both steels containing about 0·2 or 0·3% nitrogen, remarkable increase in hardness was obtained by hot-cold working at 600°C or 700°C as well as by cold working. It was concluded that such hardening was caused by an action similar to strain-aging in the deformed austenite phase supersaturated with nitrogen.
(2) It was deduced from the microscopic observation of the worked steels that the deformation by the working at lower temperature occurred mainly within grains, while the deformation at higher temperature as in the hot-cold working occurred mainly on grain boundaries.
(3) The lower the working temperature and the larger the reduction by working, the easier the softening occurred by heating of the worked steels. With the 16-15-6 type alloys, however, theeffect of working condition on the softening due to the heating of the worked alloys was not so great as the 316L type one.
(4) In general, the cold working deteriorated the bending creep properties at temperatures as high as 700°C of the two steels containing nitrogen, and the hot-cold working also did not improve their creep properties, while both of the workings improved appreciably the properties of the 16-15-6 type alloys not containing nitrogen, which showed in the solutionquenched state little resistance to the bending creep under a definite testing condition of 700°C and of 16kg-load. Under a given reduction by rolling, that is 20%, the hot-cold worked 16-15-6 type alloys with or without nitrogen at 600°C or 700°C showed the larger resisting properties against the bending creep at 700°C compared with those worked at the temperatures higher or lower than those temperatures.

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