鋼の瓦斯通氣性より觀たる青熱脆性の本性に就て(第 2 報)

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From an investigation of the gas permeability of steel up to 600℃, it is shown that Steel is capable to pass various gases easily through the grain boundary, and further the space amounts to about 0.02mm^2 in the area of 1m^2. The specimens treated with are 13-pieces of common carbon steel and 3-stainless pieces. The gas permeability of steel up to 600℃ subjects to the logarithmic decreament against the temperature rise owing to the space diminution around the grains from the grain expansion caused when heated, and there exist five points in the temperature range up to 600℃ where gas is almost unable to pass through, the points were shown to be 150℃, 220℃, 300℃, 410℃ and 570℃ thereabout respectively for all specimens of various carbon content. Now, it is brought to light that these gas stoppages, except at 220℃ and 570℃, due to the space diminution being produced among grain boundry as both the stresses given before to the grains and the stresses caused from the grain expansion by heating, relieve in results mutually acted at these points, thus giving a dense and compact structure at these variation points. The variation point of gas passage at about 220℃ and 570℃ is shown to be the space diminution produced from the grain expansion at A_O-point of steel and the recrystallization of grains respectively. By what the gas stoppage caused, were well explained from the results obtained by this work. For an example, the blue-shortness of steel is well understood as an crack or a lack of freedom in the grain deformation when a hard external force applied to it at about 300℃, because it is put in the non space state at this temperature as above described. Further, as the effect of cold drawing, it is conclused that the space is extremely diminished especially at about 150℃, and twisting stress affords generally a space increase though it produces a gas stoppage at about 410℃ where the twisting stress relieves. Next, the cause of self hardening of a springmaterial worked hard at room temperature when it is cooled from about 200℃, the nature of hardening is not yet clear up to date, can be well explained as the result of retaining yet the dense structure at 150℃ when cooled down to the room temperature, and further a increament of strength at 150℃ in shock and drop-hardness test can also be well cleared with this consideration. Now, from the results obtained the object of the annealing process of steel will be so understood as it is nothing but to relieve the stresses by passing through these relieving points at 150℃, 300℃, 410℃, and completed by passing these points repeatedly. Further, in the cooling period a gas passes more easily than in the heating as well as gas stoppage in the cooling is also little, because stresses have been relieved at most part by heating through these variation points at first, Thus, ofter the relieving of stresses it accompanies the space increament and consequently let the gas pass easily after relieving, but the gas stoppage always occurs of cause during each relieving period. The behavior on the gas permeability of Stainless steel up to 600℃ in both the heating and cooling in well similar to that of common steel described above, for the number of gas variation points and those occuring temperatures. The permeability for stainless steel simore or less smaller than common steel.
1937-12-25

鋼の瓦斯通氣性より觀たる青熱脆性の本性に就て(第 2 報)

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