In our previous paper, (1) it was reported that the intense radio noise was generated bythe arc welding machine with high frequency. A further study on the radio noise caused by such a welding machine has been carried out, the results of which are presented here. The summary is as follows. The radio noise caused by the arc welding machine with high frequency is mainly produced by parts of the lead wires connecting to a holder and a work, and in the case without such lead wires, the noise is comparatively small, i. e., the interfering radiation is very weak and the interfering voltage of the distribution line is comparatively small and is considerably reduced by the use of a group of condensers. Therefore, it may be advisable for the purpose of noise reduction to shield such lead wires.
With particular emphasis on thin plates, a series of fundamental test welding by MIG method were performed on some grades of alminum alloys (anti-corrosive) for rolling stock. The test materials included 2S-O, 3S-O, 52S-O, 61S-O plates of respectively 5, 3, and 2mm. thickness, with electrode wires, 2S and 43S ; and no preparation closed butt welding was conducted on them. The results pointed to a good possivility of Aircomatic method beeing applied satisfactorily to such thin plates as 3 or 2mm., though the thickness of plate adequate for this method has been accepted as over 4mm. The welding conditions were as given in Table 2. Table 8 summarises the results of the tensile test, bending test, hardness measurement and microscopic observation with 52S and 61S. The electrode wire 43S, wich is in general use, should be used with caution as a structural material, for its deposit metal lacks very much in ductility.
About 20 kinds of Ilmenite and Rutile type electrodes were tentatively produced and, with them, the phenomenon of SiO2 content of flux being reduced to Si and transferred to deposited metal was metallurgically studied. The results are summarized as follows : 1) The tendency of Si increase and Mn decrease differs depending on whether the slag is saturated with SiO2 or not saturated. 2) Referring to F. Korber's Equilibrium Diagram for the point immediately above the solidifying point of iron, the boundary line between Field I and II seems to be shifted to upper level. 3) The relations between apparent equilibrium constants and SiO2 content of slag and between basicity of slag and Si reduction were also studied. 4) Change of the mechanical properties of deposited metal with variation of SiO2 and Fe-Mn content in flux and appearance of fractured surface were also investigated.
The carbon dioxide gas dissociates, 2CO2_??_2CO+O2, and possesses oxidizing effect on the molten metal at high temperature. Therefore it was supposed that the filler wire used by our now welding process, described fully in report 1, has to contain much deoxidizers to gain a sound weld free from porosity. This is a report on preliminary research to take aim at these proper contents of deoxidizers in filler wire. And it was recognized that if a filler metal or a base metal contains proper contents of deoxidizers, the carbon dioxide gas shielded metal-arc welding of steels gives a excellent weld free from porosity. Manganese, silicon, titanium and aluminum are useful as such deoxidizers. Moreover silicon and titanium are effective to improve the appearance of bead. Contents of the diffusible hydrogen contained in joints by carbon dioxide gas shielded metal-arc welding are very small compared with those of joints obtained by coated electrodes.
Various tests on the inert-gas metal-arc welding of a corrosion resisting aluminum-magnesiummanganese alloy "ANP", have been performed with ANP-O and ANP- 1/4H plates, 1/4in. in thickness, and various consumable electrode wires, 2S, 52S, A54S, 56S and ANP. The present report Part 3 discusses the mechanical properties of butt-welded joints, joint efficiencies, strain-stress curves and yield stresses, distribution of deformation in a tensile test specimen and hardness distribution related with weld thermal cycle. The main conclusions are as follows; (1) The joint efficiency of the butt-welded joint increased with magnesium content of the filler wire, but practically with little difference for wires, A54S, ANP and 56S. (2) The yield and tensile strengths of the butt-welded joint was almost the same for O-and 1/4-plates, because the heat-affected base metal, approximately 6mm in width and adjacent to the weld metal, had been annealed to the same hardness with weld heat in both the tempers of base metal. Yielding and fracturing of the tensile specimen occured in the said heat affected zone, and of which the maximum temperature attained during welding was above 400°C.
Effects of nickel and chromium contents on weldability of high tensile manganese-silicon steels were investigated. Fourteen experimental ingots which contained 0.06 to 0.93% nickel and 0.03 to 0.91% chromium added to a base composition of 0.16% carbon, 1.10% manganess, and 0.45% silicon, were made by melting in an approximately 700kg acid-lined, high frequency furnace and rolled into 20mm plate. Four commercial heats which were made in a 40ton capacity basic open hearth were tested together for comparison. Various weldability tests ; namely, tensile test, V-Charpy impact tests, Weld-maximum hardness test, Jominy test, kommerell test, Kinzel test, Slit-type cracking type, CTS cracking test, Gas cut bend test, and Fillet-weld break test were used. From the results of tensile and V-Carpy test described in the present paper, the following conclusions have been obtained ; 1. The tensile strength increased at a rate of approximately 3kg/m2 per 1% increase of nickel both in as rolled and normalized conditions, and 3kg/mm2 in as rolled condition anp 6kg/mm2 in as normalized condition per 1% increase of chromium. 2. Nickel increased the yield strength at a rate of approximately 4 to 5kg/mm2 per 1% increase while chromium showed no effect. 3. The energy transition temperature in V-Charpy test was lowered by nickel addition, but was raised by chromium. However, distinct relationships were not found between the 15ft-lb transition temperatures and those alloying contents. 4. The effect of nickel or chromium content on the tensile and yield strengths was very slight, provided the contents were limited in a range of nickel less than 0.25% and chromium less than 0.10%. However, the 15ft-lb transition temperature seems to be lowered slightly and the tensile elongation to be increased appreciably when the contents of nickel and chromium were reduced extremely, but the energy or shear fracture transition temperature is not affected.
Generally when steel sheets are hot rolled, it is a well established fact that if the temperature of the finish rolled sheets becomes lower at a certain range without having any effect of cold working, then better notch toughness is obtainable. The authors have succeeded in obtaining sheets of 22mm thick which we manifested high notch toughness just by regulating finish roll temperature. Summaries were obtained as follows ; (1) All steels (A, B, C, D and E) comply with German HSB50 steel standard in the mechanical and DVM impact value at 0°C (2) Especially Steel "C" (finished at 740°C), "D" (700°C), and "E" (650°C) show the satisfactory result in the notch toughness after strain aged and comply with HSB 50A steel standard.