The first part of this paper, contains the results of the fatigue tests made with 7 plain carbon and 5 alloy steels in their verious tempered conditions. From the results we discussed the followings;
(i) Relation between fatigue and carbon content. (ii) Relation between fatigue and tempering temperature. (iii) Relation between fatigue and applied load. (iv) Effect of special elements on fatigue. (v) The merits in adopting lower tempering temperature is also demonstrated for the materials of some construction uses such as machine parts and others.
The second part of this paper deals with the theoretical consideration for the mechanism of fatigue under alternating stresses, by which we explained the experimental results shown in the first part.

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The writer and R. Ishiga and T Naito contributed a paper to this Journal in Dec. 1925, under the heading "On the Quantitative Analysis of Sulphur in Iron and Steel". The chief points in that paper are: (1) The totals slphur ill pig-iron is determined by the gravimetric method, the sample being oxidized by nitric acid, while the volumetric method, dissolving at reducing condition, sometimes does not give the total amount of sulphur. (2) The solubility of the compound of sulphur in pig-iron depends not on the qunantity of sulphur but on the manganese content. (3) In pig-iron with a low manganese content, such as less than 0·3% of manganese, an insoluble compound is always formed, but it may be rendered soluble by the application of heat.
The paper also treats of the insoluble sulphur compound formed in grey pig-iron containing less than 0·3% of manganese but with a specially high content of sillicon. This compound is decomposed by adding manganese when the sample is in a molten state, according to metallurgical reaction, and unstable under annealing, showing decomposition at 600c-900c. Many samples are prepared by melting white and grey pig-iron under the different compositions of Mn., Si. and S., and chemical analyses, microscopical examinations and heat treatments were carried out in order to find the kinds of sulphur occurring in those samples. Well-known compounds of sulphur in iron are FeS or MnS. both being distinguishable under the microscope. An insoluble sulphur compound is neither FeS nor MnS, but is only formed when Fe₃C, FeS and Fe₂Si are intermixed, and is probably a complex compound. This hypothetical compound may occur in a state of solid solution or separate structure, both being unstable. Remelted pig-iron shows a quite different state from the original one.

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[in Japanese]

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[in Japanese]

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