A study has been made under the notion that, in mixing Mn and Si in the flux of welding electrode, the deoxidation theory in steel making (the co deoxidation by Mn and Si and the various ensuing phenompena of the deoxidation products) must have much to do with the welding deoxidation also. Some of the findings follow : a) The coated welding electrode is remarkably improved by mixing a proper dose of deoxidation agent in the flux, and the conditions for the [Mn] and [Si] concentration ratio considered proper in steel making are also the conditions applicable to welding. b) In order to obtain specially good mild steel arc welds, it is desirable that the concentration ratio be, including the amount in the core, [Mn]: [Si]=4.0%:0.5%.
In this research, heat conduction is limited to physical systemes governed by linear differential equations. Generalizing the conception of heat source, the author proposes a general solution of unsteady heat flow due to the heat sources which change the distribution, shape and place of growing heat energy such as chemical change, radioactivity, Joule's heat of electric current etc. Main solutions are shown in equations (P-1) to (P-7). Specializing equations (P-1) and (P-7), the general solutions of heat flow corresponding to all welding conditions of heat flow in simple form solid are derived. But the above-mentioned limit is doubtful in such high temperature phenomenon as welding, there-fore their effects should be investigated in the future.
The authors earlier reported in Part I that the components of arc atmosphere produced during metallic arc welding would be CO, CO2, H2 and H2O and their composition would depend upon water gas reaction at high temperature. In this paper, the components of exact arc atmosphere directly around the arc during welding using various fluxes of electrodes were studied. Electrodes used contained cellulose percentages varying 0, 4, 8, 10, 13, 15, 17, 20, 23 and 25, in addition to the base mixture of Ilmenite, Kaolin, FeO, MnO2, SiO2, Fe-Mn and Al2O3. Five well-known types of electrodes generally used in Japan, two slag shielded types, two medium types and one gas shielded types were also employed. Arc was started in 1-3mm Hg vacuum welding tube, using Akazaki welding process. Gases were collected in two reservoirs up to about 1.2 atm and then they were analized. Welded deposits and slags were also analized. The important conclusions obtained in this study are as follows: 1. The components of arc atmosphere obtained in metallic arc welding were CO, C02, H2 and H20 and their compositions depended upon water gas reaction at high temperature (1200°C-1700°C). 2. The greater the cellulose percentage contained in. electrode flux, the more reducing gas in arc at-mosphere was formed. 3. Hydrogen absorbed in molten steel from atmosphere at 1550°C, 1600°C and 1700°C were calcu-lated with application of Sievelt's law and Chipman's data, and of Christensen's formula which combines partial pressures of hydrogen in atmosphere and FeO content in slags.
Based on previous fundamental investigations the authors studied on the effects of various operating conditions. Steel plates, 200×200×2.3mm, were heated and cooled rapidly at the center by oxy-acethylene flame under difierent conditions with heating time varied 2, 4, 6 and 9 sac; the radius of heated zone, 5, 10, 15 and 20mm. Radial shrinkages were then measured; They agreed with theoretical calculations made on the the theory advanced in Part I. In these experiments the maximum value of radial shrinkage increased as the heating temperature or time was raised : but from the viewpoint of the property change of the plate the temperature proved most adequate at about 600-650°C, while the most adequate heating time was 2-3 sec with No. 500 torch applied. The most desirable diameter of heated zone was 22-24mm, because the maximum radical shrinkage was then greatest. The preferrable pitch of heated zone is about 2.5 times its diameter, i. e., 50-75mm from the viewpoint of the shape of hole drilled on cover plate.