The oxygen lance method and the big acetylene-oxygen blow pipe method were studied. Both are the first trial in this country, so we started with making apparatus and arrangements. A 4 ton steel ingot was to be test-cut. The size of steel pipe for the lance, the gas (oxygen) pressure and consumption, the time required for cutting, etc. were studied. A blow pipe, of which the diameter was 11.5 mm at the outlet, was designed and prepared, as well as the other necessary arrangement of the accumlator and leading arrangement of gas and other necessary attachments. The time, we could succeed in cutting a steel ingot of 107 cm in thickness. In conclusion, the lance is easier to arrange the apparatus, but the manipulation is inferior to the blow pipe.
The temperature rise of torches under various conditions were measured with thermocouples at several positions of each torch, tip positions relatively corresponding in each torch, as sown in Table 1. The test results revealed that; (a) Heat radiation from flame itself and base material was the principal cause of temperature rise. (b) In Type II', the maximum temperature was found to be about 300°C. This type of torch is considered to be the most desirable in gas welding. (c) Tip temperature could be risen up to about 500°C under some conditions, but "back fire" took place above this temperature. (d) The tip temperature rises were classified based on tip material and style of torch.
It is evident that the stress-peak can be relieved by peening operation, but this operation inevitubly produces the plastic deformation at the peened position and increases the hardness of its part. In this report we examined how peening operation affects the welded joint, especially, the notch toughness; and cohfirmed that this operation on the deposit metal was out of problem, but peening on the parent metal near the weld deposit was harmful from the point of notch toughness.
Hydrogen absorbed in weld metal during welding was reported by many investigators to contribute to the formation of cooling crack, fisheyes, porosity on bead, or ice flower like structure in steel welds. This report describes the relation between the types of mild steel electrodes and the hydrogen contents in the weld metals, and moreover demonstrates the effect of the moisture absorption in the covering upon the hydrogen contents of welds. The results obtained are as follows; Electrode coating containing organic materials gives large amounts of hydrogen in weld metals, and the one almost free of hydrogen producing materials low-hydrogen weld metals. However, the latter, low-hydrogen type electrode, is more prone to he affected by the moisture absorption in the covering than the former. Therefore, it is necessary for this type of electrode to be dried thoroughly before use. For the other types of electrodes, it is possible to eliminate to some extent the effect of hydrogen by adequate annealing after welding.
In spot welding of 24ST Alclad sheets, authors have performed some experiments on the variation of shear strength to investigate whether the variation of shear strength is affected by the variation of contact resistance, and the measuring error of electrode pressure.
In the previous papers the authors reported their simplified method to evaluate the notch-sensitivity of materials by the notched slow bending test with U-notch Charpy specimen. This supplement dealts with the similar experimental results with V-notch Charpy specimen.