This paper deals with the influence of Si, Mn, W, V and Mo upon the quench hardening of Steel. Specimens were quenched at 750°, 800°, 850°, 900°, and 950°C in water and oil. The hardness was measured by means of a Vickers' Hardness Tester, at every distance of 1mm. apart along a diameter on a section which was ground off 5mm from the surface. By a differential dilatometer, the influence on the transformation point was measured. The micro-structure was also examined. From the hardness distribution on the sectional surface, the following conclusions are deduced:
Si increases the quench-hardening effect of Steel, and is available for hardening throughout the range from edge to center at a higher quenching temperature. but in the vicinity of 800°C. the effect is less than plain carbon steel.
Mn makes, therefore, quench-hardening of steel easy even at a low quenching temperature, the more manganese causes the greater quench-hardening effect. At a higher quenching temperature and with further increase of Mn, however, the hardness distribution at the edge of specimen indicates a lower value owing to retained austenite.
W increases the effect of hardening. At a low quenching temperature and with about 1·0% of W, there is little difference in hardness at the edge and center, when W content is increased to 1·5-2·0%, the edge ipdicates a hardened state for only 1-2mm in depth, but near the center it resembles plain carbon steel.
V helps to harden steel and causes little difference in hardness. The specimen containing V, may however, be queuched from 950°C in water or oil, whilst V has a less effect on the depth of hardening.
Mo. even if it is contained a little, affects the hardness markedly, and at a higher quenching temperature the hardness becomes lower than that at a lower quenching temperature.

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Hot sheared surfaces of rimmed steel billets show always various appearances. The author classified them into five kinds and pointed out that these appearances of billets depend mainly upon their degree of soundness.
Conversely, it is possible to determine the degree of soundness of a billet by the apperance of its sheared surface, which may profitably be applied to the selection of the material for its proper use.

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The authors present in this paper the results of the study on the spot welding of 18/8 stainless steel sheets which contain a certain amount of Si, Ti, Mo and Cb raspectively.
The work carried out by the authors is outlined below.
(1) The effect of variation in the electrode pressure, the duration of welding and the amount of electric energy consumed on the shearing strength of the welds between the plain 18/8 sheets were investigateg.
(2) The examination on the welds of the 18/8 sheets containing Si, Ti, Mo and Cb either alone or in combinations was made with respect to the harness, shearing strength, tensile properties, macro -and microstructural characteristics, blow holes by means of X-ray and the corrosion-resistance.
From the results obtained, the authors conclude that the mechanical properties of the spot are improved by the addition of Ti, Mo, Si, Si+Ti, or Si+Mo, and the corrosion-resisting property, especially against that of the imer-erystalline type which takes place around the spot, is considerably raised by the addition of a suitable amount of Ti, Ti+Si or Cb respectively.

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In the previous reports the corrosion tests of many kinds of cast iron having various compositions and structures were carried out, and determined that the corrosion amount in a dilute nitric acid solution (0·5N) is very small with the gray. cast irons these contain free ferrite or greater amount of sulphide in pearlite matrix, this kind of gray cast iron evolves a pretty amount of gas in such a dilute nitric acid while the gray cast irons of pearlite matrix do not evolve any gas in the nitric acid solution of the same concentration. Then the rate of evolution of gas was measured and the chemical composition of the gases were determined. The gases evolve always periodically and greater part of them are hydrogen. From this fact and other experimental results, the writer concluded as following. In a dilute nitric acid gray cast iron first evolves hydrogen as a result of the electrolytic action caused by graphite (Cathode) and ferrite (Anode) while the ferrite is anodically oxidized and temporarilly brought to passive state, so that the dissolution ceases. In the next stage the passive state is destroyed by the acid and direct reaction between iron and nitric acid takes place, in this stage ferrite is severely attacked but non gas is evolved and instead of hydrogen ammonia and hydroxylamine these are soluble in the solution or complex iron salt are formed.
In the 3rd stage hydrogen is evolved again by electrolytic action as the former case. These changes are repeated periodically in the progress of dissolution of gray cast iron in a dilute nitric acid.
In another experiment the electrode potentials of various structural constituents of gray cast iron were measured in a normal ferrous chloride solution against the normal calomel electrode at 30°C. The results are as following; graphite cathodically treated in 1N hydrochloric+0·2750^υ, Fe₃C-0·2357^υ, Fe₃P-0·2971^υ, MnS 0^υ, FeS-0·3600^υ, [60%MnS+40%FeS](solid solution)-0·4407^υ. Also the E.M.F. of galvanic cells consist of ferrite and one of these constituents were measured in 0·5N hydrochloric acid solution at 30°C, and the following results were obtained; graphite⁺-ferrite- 0·9810^υ, graphite⁺-ferrite^-(containing 0·34% Cu)0·9535^υ, Fe₃C⁺-ferrite-0·3508^υ, FeaC⁺ -ferrite-(containing 0·34%Cu) 0·3064^υ, Fe₃P⁺-ferrite-0·2100^υ, [MnS+FeS]⁺-ferrite-0·3260^υ.
In the 1st and 2nd report the writer concluded that gray cast iron dissolves in a dilute hydrochloric acid mainly with the electrolytic reaction caused by local galvanic cells consist of ferrite and graphite or other noble constituents. These present experimental results gree with the former results of corrosion test as described in the previous reports.

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