Though the studies about the consumption of the electrode in arc have been made by many researchers, their results are still not enough to analyze the phenomena of consumption. It is our aim to investigate the characteristics of consumptions of cathode and anode inarc. Summarizing our rensults of experiments upon the consumption-rate of Iron-electrode of arc in air, we have as follows ; a) The consumption-rate of anode is not almost influenced by the diameter of electrode, but a little by the gas surrounding it. b) The effect of Joul's heat on the consumption-rate of electrode in arc appears suddenly when its measurement is done as to the large length of consumption in large current-density. c) The consumption-rate of cathode is remarkably influenced by the condition of its surface and thediameter of electrode. d) The consumption-rate of well-cleaned cathode increases as current increases beyond some extent.
Relative values of heating time and current density for spot welding when the plate thicknesses are varied for various materials of differrent physicall constants are considered under the following assumptions: 1) The contact area of the electrode does not varies during welding 2) Heat flows only in the direction of x to electrodes. 3) Temperature at the contact surface to the electrode is assumed to be zero 4) Contact resistance is neglected 5) Electrical resistivity varies as ρ=ρ0(1+αθ), while other physical constants being assumed as constant. The relation of reasonable heating time t and current density δ can be discussed easily from the fundamental equation (8), and the relations are shown in equations (9). The calculated value are shown in Table 3.
This paper reports the results of V-Notch Charpy Impact tests performed on one-pass weld specimens and transition temperatures obtained. The results were as follows : (i) The transition temperatures of one-pass weld specimens were always above the room temperature. (ii) The Charpy Impact values at temperatures below room temperature were low irrespective of the coating types hnd steel plates, giving the lower values than those of base metals (mild steel plates) (iii) The Charpy Impact values of one-pass weld specimens could be improved by multipass welding and gave much higher values than those of base metals.
According to our opinion, it is obious that the filler wire must contain more amount of deoxidizers than that for killed or semi-killed steel, in case of the C. S. Arc Welding of rimmed steel. And these amounts are to be variable according to the conditions of welding, e. g. thickness of plate, shape of groove and treatment of surface of plates to be welded. Authors reported already that one or two-pass welded joints of rimmed steel, 10mm in thickness, with the C. S. Arc Welding Process are very satisfactory. In this report, they investigated the sillicon content enough to perform multi-pass welding of thicker rimmed steel, 20mm in thickness. And it was decided that the content must be over 0.5% Then they studied transtion temperatures of weld metals, depositited by the C. S. Arc Welding Process using various filler wires, by means of V-notch chary impact test. The temperatures ranged from-34°C to-92°C. The absorption energies at 0°C ranged from 5.3kgm/cm2 to 19kgm/cm2. These values were compared with those obtained by the submerged warc elding and by the arc welding with coated electrode of low hydrogen type. It was recognized that carbon contents of weld matals by the C. S. Arc Welding Process using low carbon filler wires (0.01%C) increased over that of filler wires and their values became a constant, about 0.1%C. But the value of porous weld metal was 0.05%C.
In this report, in the first place, the authors constructed the continuous cooling transformation diagram in case of rapid heating maximum temperature 1100°C in the same way as Report 1. Then they considered generally on three diagrams already obtained. As the rapid heating maximum temperature becomes higher, the positions of the beginning curves of transformation and the ending curve of pearlite remove to the longer cooling time and lower temperature side, and the critical cooling times (C2' Cf', Cp' and C6') become larger. As the cooling time, from A3 point to 500°C, becomes shorter, namely, the cooling rate becomes larger, the specimens after cooling show the following tendencies: (a) the ferrite decreases and harder structure, e. g. martinsite, increases and the hardness of specimen becomes larger, (b) the absorbed energy by impact bend becomes larger with decrease of ferrite and increases of harder structures, (c) but as the cooling time becomes smaller over the certain limit, the absorbed energy becomes smaller suddenly on the contrary and the bend angle by impact and slow bend becomes also smaller suddenly. (d) the tendencies of (b) and (c) above mentioned are remarkable in case of specimens cooled from maximum temperature 1300°C.
The recoveries of the notch toughness of structural high tensile steel by tensile prestrain at room temperature were investigated through the standard V-notch Charpy test. The results obtained are as follows: 1. It has been generally conceived that impact value, lateral contraction and shear percentage decrease with increasing prestrain, but the recoveries of toughness at the low temperatuae range in the transition curve are recognized at about slight necking-point which is before maximum load (the 1st recovery) and at about maximum load-point (the 2nd recovery). 2. The recovery of lateral contraction is small and, on the other hand, that of impact value or shear percentage is to or above the toughness of virgin steel. 3. Ductility transition temperature rises with increasing prestrain, but it drops to that of virgin steel at the 1st and the 2nd recovery-points. 4. Fracture transition temperature is not almost affected by prestain, but it drops below that of virgin steel at the 1st and the 2nd recovery-points. 5. The recovery-points mentioned above are not changed extensively by testing temperature, within this experimental range.
Web plate of welded-built-up girder is distorted by the welding of stiffener as shown in Fig. 1. This distortion was measured in the girder as shown in Fig. 2. Stiffener arrangement is shown in Fig. 3. Distortion of each panel is given in Figs. 5 and 6. Maximum deflection of the panels except for the end panels 4 and 4' is about 2.1-2.5 mm, and it agrees with theoretical value obtained by eqs. (1)-(4). (see previous reports). As the method for decreasing the deflection of panel, we considered the following three methods : (1) Method of changing the stiffener space (l1). (see Table 1 and Fig. 7). (2) Method of using additional constraint as shown in Fig. 8. The results are shown in Table 2 and Fig. 9. (3) Method of preheating the back surface of web plate when welding the stiffener. The results are shown in Fig. 10 and Table 3.
In order to investigate the relation between the efficiency of the strap, the length of strap and the kinds of load, the authors performed bending tests on box girders which were reinforced with straps. Five kinds of test specimens were used : a box girder itself and four box girders with box-fillet welded straps of which breadth (B=60 mm) and thickness (T=10 mm) were kept constant and length varied (L=60, 120, 200 and 300 mm). Through the wire strain gage measurement, they obtained the stress distribution of strap, and then mean stress of strap. The efficiency of strap, ratio of the mean stress of strap to the value calculated by the beam theory increased rapidly with L, reaching 80% at L=200 mm (about 3.3 times breadth), and beyond this limit practically became saturated, showing little further increase. Difference of the efficiency was little regardless of the position of the attaching plane. The theoretically calculated stress of strap showed the same inclination as the measured one.