At present, the method published by C.T. Gayley and W.H. Wooding has been utilized broadly on the determination of total water content in electrode coatings. In this report, the total water content in electrode coatings and its materials used generally in the field of manufacturing welding electrode were determined after the discussion on the method. Still more, the absorption velocities of moisture in 90% relative humidity were investigated for some of the low hydrogen type commercial electrode coatings. Results obtained are summerized as follows. 1. On the discussion of the method reported by C.T. Gayley and W.H.Wooding; 1) In this experiment, a quartz glass combustion tube was used instead of the high temperature McDanel combustion tube. When used a rubber stopper at the one end of the tube, it was necessary to cool by tap water, because of considerable amounts of water evolved from the stopper at high temperature such as 1200°C, but it was more succesful to replace it with a ground quartz glass cap. 2) As the air intruded into combustion tube when the stopper was opened to insert the sample into it and gave a considerable error on the results, it was advisable to correct the water content obtained in the case of more than 50% relative humidity. 3) When concentrated sulfuric acid in drying tower was used as a desiccant for oxygen, it gave a drying effect on de-hydrite, in "U" tubes, therefore 90% sulfunic acid was replaced. The result was satisfactory as reported by C.T. Gayley and W.H. Wooding. 4) It was necessary to ignite the combustion clay boat (N.T.K.B.) at 1200°C for about 2 hours for one boat and 4 hours for two boats in the same time. However, the time required to ignite was reduced to about a half by pre-heating the boat with a gas burner. 2. On the determination of total water content in coating and its materials; 1) The determination of total water content in twenty two coating materials were made from air dried condition. 2) Water content of manganese dioxide, asbestos, talc, mica, No.2 sodium silicate, No.3 sodium silicate, potassium silicate kaolin, and commercial welding electrode coating were determined at various temperatures for one hour. Above all, the total water content and the temperature necessary to evolve it for mica, talc, and asbestos were higher than the others. 3. Relation between the total water content in electrode coating and the volume of hydrogen evolved from deposit metal was liner for a given electrode. 4. The absorption velocities of moisture in 90% relative humidity for five commercial electrode .coatings were different remarkably each other.
The melti-arc has been so widely used in welding, but it is not. evident how the arc can transfer from one electrode to another. Authors have deeply studied the after-arc phenomener, and applied our theory to the clarification of the transfer mechanism of the multi-arcs. We will report our results as we have acquired its clear solution. In our method, we measured separately the currents flow through the two electrodes. In addition, we used an interrupter in a circuit of a current in order to lead the transition of in our accords. We investigated the variations to time of the currents, voltage and arc-resistance at the vicinity of the transition. Our results and considerations lead to the following conclusions ; a) The transition happens when the arc resistance becomes a certain constant value. b) The interval of the transition is about 1/100 sec. c) The reparate currents flow at the interval of the transition, but the essential arc seems to have already transfered. d) Strictly speaking, the arc voltage should go down slowly. and not abruptly. e) In general, the abrupt increase in the arc voltage by some reasons (for example, the dsecend of globuls except the transition induces the transition. f) The number of the abnomal increases in the voltage are larger than the numbers of the transitions. g) When we induce the. transition by the interrupter, the arc voltage decreases without fail.
In this paper, flux compositions used for brass welding by oxy-acetylene flame were as follows; (1) Fused borax-boric acid system (2) Mixed borax-boric acid system (3) Fused borax-boric acid-sodium chloride system (4) Fused borax-boric acid-disodiurn phosphate system (5) Fused borax-boric acid-NaH. NH4PO4 system These fluxes were applied as a paste to the welding rod, but did not painted on the surface of the parent metal. From bead apperance, slag fluidity, porosity and mechanical properties on Vee butt joint, borax 20%, boric acid (80%) flux is excellent. Addition sodium chloride, disodium phosphate, NaH. NH4PO4 to borax-boric acid flux is not advantageous.
The notch-sensitivity of the heat affected zone produced by heat input 51, 428 Joule/in. and 38, 571 Joule/in. weld bead were studied both on the rimmed and killed steel, using the Bead-Weld Slow Bend specimens (See Fig. 2, 3). In addition to these tests, the effect of specimen width (between 10 mm to 30 mm) on the notch toughness were studied. The experimental results are as follows; (1) As generally well known, the notch toughness of the killed steel are better than rimmed steel both on the base metal and the heat affected zone. (2) The heat affected zone produced by heat input 51, 428 Joule/in. bead-weld has better notch toughness than the heat affected zone produced by heat input 38, 571 Joule/in. bead weld. (3) The heat affected zone produced by heat input 51, 428 Joule/in. shows nearly the same notch toughness as the base metal both on the killed and rimmed steel. (4) For the specimen width, 20 mm width specimen and 30 mm width specimen have nearly the same notch toughness but 10 mm width specimen did not show the remarkable transition tendency in our experimental temperature range.
The brittle ranges of the multi-pass welded parts arc investigated, using both Killed and Rimmed steels, low-hydrogen type and ilumenite type arc-electrodes. Further, the variation of the impact values after heat-treatment are described. As the results of these experiments followings are known ; 1) Variation of the impact values after heat-treatment are somewhat different depending on the part where the impact specimens are adopted. 2) It was recognized that there exist inferior toughness in the bond. 3) The most brittle part seems to be more apart from the bond than in the case of single-bead weld. Using the synthetic impact specimens, improvement of the toughness in the neighbour of bond are investigated. Further, reliability of this specimen are considered comparing with the test results described in the previous report. The better impact value seems to be gained after the heat-treatment in the neighbour of 700°C. Rolled directionality of the parent plate must be considered to calculated the synthetic impact value from the common testing results. Considering some correction caused by directionality, it seems to be reliable to use synthetic impact specimen.
As the most fundamental case of shrinkage distortion in welded joints, we have studied on the transverse shrinkage distortion of bead-on plates. Characteristics of transverse. shrinkage distortion are shown in Fig. 4. Both angular distortion and shrinkage produce near the weld bead, and the distorted portion correspondes to the range heated above 150-200°Cwhen welding (see Fig. 5). Comparing the results of Fig 1, 2 and 3, we know the shrinkage distortion appears approximately uniform except for the ends of weld. To analyse the deformation of bead-on plate we assumed that shrinkage forces and shrinkage moments act as shown in Fig. 6, and inherent strain, the cause of distortion, distribute as shown in Fig. 7. Transverse shrinkage and angular change are then represented by eqs. (1) and (2). Fig. 8 shows the characteristics of these equations. Simple formulas of transverse shrinkage and angular change are obtained from Fig. 8 and the results of our former study (see Reference 1), and they are eqs. (6) and (7). Experimental results are shown in Fig. 9 and 10.