In this paper, the change in the magnetic property of steel subjected to repeated tension and compression is studied as an aid to the analysis of the fatigue of mild steel. A specimen of annealed 0.3% C-steel is fitted to the Heigh's Fatigue Tester, and the prescribed tensile and compressive stresses of six grades within the range of 12-38kg/mm² are applied a definite number of times, that is, more than 10⁴ times. Then, after the threaded parts of both ends of the specimen are cut off, the parallel part is finished and the hysteresis curve is obtained by means of the method of easy and continuous search for the hysteresis loop of the specimen utilizing the magnetometer and the nomograph such as were reported in 1953. The change in the magnetic property due to fatigue was observed by varying the number of repetition and applying various repeated tensile and compressive stresses.
Some of the results are summarized as follows: under the experimental conditions, the residual magnetism andthe coercive force are almost constant for the various stresses regardless of the number of repetition: the hysteresis loss scarecely changes when the stress is under a certain value regardless of the number of repetition but tends to decrease as the number of repetition increases when the repeated stress goes beyond a certain limit (which agrees with the fatigue limit), and this fact is consistent with that achieved by the method of rotating bending or repeated stress: and the susceptibility and other several magnetic properties seem generally to have the mean value of the values of the annealed steel and the cold worked one, and decrease gradually within the range of these two values with the increase of the number of repetition.

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In the 1st. and 2nd. reports, shot peening conditions, shot speed and shot number per unit area, etc. were not related. Thus, to decide the working conditions of shot peening process, a new centrifugal type shot peening machine (for experimental use) was devised and manufactured, and the ability tested.
The machine facilitated the test conditions: shot speed of 30-85m/sec, dispersion angle of 25° and shot flow rate of about 9kg/min.
The residual stress and fatigue strength were measured, and the optimum conditions were studied by shot peening the spring steel (JIS sup-6) under the conditions of 0.5, 0.7, 1.0 and 1.2 mm Cut wire shot and 7.86m/min conveyor speed, in addition to the above conditions.
The expeimental results are as follows:
(1) Shot velocity was 1.25 times the peripheral velocity of the impeller, the shot size having no effect.
(2) There is no relation between shot distribution and shot size and velocity.
(3) Peening process hardly hardens quenched and tempered spring steel.
(4) When the shot energy determined by the shot size and velocity is equal, the surface residual stress of the specimen is found to decrease beginning at the point of same coverage.
(5) Just before the above condition is reached, when the surface residual stress begins to decrease, the fatigue strength shows the maximum value.
(6) The best working condition seems to be full coverage with shots of about 1×10-4kg-m energy each.
(7) Within the range, investigated the max. and min. fatigue limits under pulsating plane bending were 110kg/mm² (0.5mm. shot, 49m/sec., 94% coverage) and 62kg/mm² (1.2mm. shot, 82m/sec., 98% coverage) respectively.

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Four kinds of Si-Mn high strength low alloy steels were hot rolled into plates of 12 and 22 m/m in thickness. Schnadt impact test was carried out in the range of temperature from -80 to 97°C to investigate the effect of the degree of reduction in plate thickness, gas cutting, shearing, welding, and chemical composition on the transition temperatures and impact properties of these plates.
The results obtained are as follows;
1) Schnadt impact properties of the specimens taken from the thin plates are generally superior to those of the specimens taken from the thick plates.
2) Gas cutting seems to reduce the notch sensibility of the plates which is rather advantageous, while the sheared surface has the trend to be notch sensible. Weld metal used is excellent in toughness.
3) Suitable contents of aluminum and nitrogen in the form of aluminum-nitride seem to have a good effect on the impact properties of steel plates. Attention should be paid, therfore, in the deoxidation of molten steel to leave a small content of metallic aluminum in the steel.
4) The temperature of complete brittleness (i.e. Bifractance defined by Schandt) of the specimens is lower than -15°C when the Venant number is assumed to be 20, while that of full plasticity (Octafractance) lies in a relatively high temperature range. This tendency is more conspicuous in the thick plates.
5) Transition temperature is lowered as the number of Venant is increased. Transition temperature of the thin plates is lower than that of the thick plates.
6) These results show that the test plates belong to high or moderate class of high strength low alloy steels when compared with the various foreign types of steels of the same kind.

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The drying methods adopted hithertofore have used the hot air which imparts heat on to the surface of the samples by conduction and convection.
These methods may be briefly called "the extra-heating methods".
In the case of drying by infrared rays, however, heat is transmitted by radiation not only on to the surface of the samples but also directly into the inner part. In comparison with the conventional methods, it may be called "the intra-heating methods".
The infrared rays drying, as expected easily from the drying mechanism, gives much more uniform drying compared with hot air drying and also shorten the drying time due to the higher speed of drying. At the same time a good influences on the physical properties of fibers can be expected owing to the shorter time of the contact with hot air and the heat treatment of the fibers.
From the experiments made with the rayon tow (moisture content of about 180%) of which the total deniers is 290000 and monofilament denier 1·5, the following excellent results were obtained different from usual methods.
As to the rate of drying, the infrared rays drying method shows 10-15 times higher value than usual methods, so it becomes easily possible to shorten drying time to about 1/50.
Regarding the physical properties of treated fibers, the infrared rays drying shows the higher values about both the ratio of dry and wet strengths (St.W/St.D), and dry and knot strength (St.K/St.D). From this fact it can be presumed that. the crystallinity of cellulose can be increased by the heat effect of fibers.

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The methods adopted hithertofore to determine the moisture content of fibers are called drying methods. It takes long time (3-4 hours) by these methods, so, many electrical methods have been developed to obtain more rapid measurements. By these methods it has become possible to measure almost instantaneously, but these methods have insufficient accuracy and must be calibrated for each given condition.
We have made an equipment by which the moisture content can be measured in a short hours (for 10-15 minutes) making use of infrared rays instead of the usual hot air in order to shorten the time for measurements.We report in the present paper the results obtained by this method. This equipment is composed by the combination of the usual infrared rays lamp for drying and the balance for weighing the samples. The moisture content is indicated on the moisture scale utilizing the variation in the weight caused by drying. This equipment has an accuracy of 0.05% in regard to the moisture content.
The moisture vaporized by drying varies with the voltage of the infrared lamp and indicates as the higher value as the voltage becomes higher. This higher value means that the degree of the drying of fibers is promoted as much.
The value obtained by this method is different from that of usual methods according to the drying condition, therefore it is necessary to obtain previously the calibrated value of given conditions beforehand.
One of the characteristics of this drying method is that the same drying rate diagram is obtained regardless of the different initial moisture content, if measured in the same drying condition.

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