The authors prepared low-carbon steel filler wires of various manganese and silicon contents on trial, and performed experiments on oxy-acetylene gas welding using them. In this case, mild steel plates of different thickness were butt-welded by weaving and backhand techniques. Next, mechanical properties of deposited steels were measured and bend tests of welded joint were also performed. Then the authors investigated effects of chemical composition and surface-condition of welding rod on mechanical properties of deposited steels. The steel rods containing proper amounts of manganese and silicon were excellent as gas welding rods for steel. The low carbon steel rods containing 1.3-1.5% Mn an 0.1-.03% Si are suitable for gas welding of mild steel. And the suitable contents of manganese and silicon appear to be 1.6-1.8% Mn and 0.1-0.3% Si respectively for the gas welding rods of high tensile steels.
For the purpose of clarifying that the anode-and cathode-fall serve in determination of the meltingrate of welding electrodes, some precise experiments and consideration have been carried out. It has been confirmed from their results that, for deciding the melting-rate, the arc voltage is not always essential while these two falls are indispensable. It has been understood that, according to the kind of materials covering the electrodes, the magnitudes of the two falls and the positive column vary, and the arc voltage also varies in consequence. It has been made clear that the magnitude of the falls can be measured with a considerable accuracy by experiments.
Titanium has very superior properties, it is used as stractural stuff for Jet engine in American, but it willl react easily with atmosphere when heating at high temperature or at molten state and it produce the substance of very ductilless, therfore, it is necessary to prevent the welded and heat affected zone from reacting with atmosphere during welding of it. The authors studied on characteristics of welds by using argon gas shielded arc welding and we obtained from the study folloing the conclusions. Titanium has a good penetration than other metals, its penetration was very good in welds with larg welding current and low speed, but welded face was becoming in welds with larger current than 80 ampere and lower speed than 250mm/min. the best welding condition obtained in this investigation was when >0-80 ampere, 300mm/min. and argon gas flow content of 15 c. f. h. (about 7l/min), and shown that the results of tensile and bending test were very good.
Series of double blow impact test were performed on V-notched Charpy specimens at temperatures, -50°C to 70°C. The depths of cracks created by first light blows. were detected by dripping etching solution at the notch roots of specimens and then breaking them by the second standard blows, which demonstrated the energy for propagating these cracks. Also, standard single blow Charpy test was carried out at the same testing temperature. Combining these three energy values, the effects of velocity diffeerences were eliminated from the first light blows. Series of tests were made at a settled temperature, with varying amounts of energy by first blow, thus the energy for crack initiation could be determined. The same steps were taken at different test temperatures. The Fig. 3, 4 and 5 show the experimental results. From those figures, the effects of temperature on the energies for crack initation (Wi) and porpagation (Wp) were determined as in Figs. 6, 7 and 8. Then, the meannings of 15 ft-lbs or 1/2 maximum energy transition temperatures could clearly be understood. Also the percent shear-temperature curves in Fig. 12 were proved to possess close correlations with the Wp-temperature curves. For three kinds of steels investigated, the orders of the locations and the maximum values of Wi-temperature curves coincided well with those of WP-temperature curves. But there was no correlation between the order of location and the maximum values of Wi or Wp-temperature curves in the three steels. Further, the effects of impact velocities on Wi and Wp at various temperatures were discussed making use of the test results in Figs. 3-5.
Using four Japanese rimmed steels, the authors have done torsional test of round bars within the temperature range of -80°C to+200°C and compared these results with the notch toughness investigated by Charpy and notched slow bending test using U and V type standard Charpy syecimens. In order to discuss the judgment of the uotch toughness of materials from torsional testing results, we abopted the criterion, ψ=breaking twisting moment/breaking twisting angle (see Fig.8) Then we found the notable : (a) the valve of ψ remained constant within the experimental temperature range (-80°C-+100°C), being independent of testing temperature (see Fig. 7) and (b) material of which the value of ψ is lower shows the lower transition temperature (see Fig.9). Consequently, it could be said that the notch toughness of material may be specified by the value of room temparature as well as by the value of ψ and Φ at room temperature in tensile and notch slow behding test respectively.