For the desing of a burner of surface quenching, the fundamental data are demanded on the relations among the kinds of materials, the shape, size and depth of quenching and other functions. We operated the experiment as, following: Test specimens : square sheets of 10 X 100 X 200mm and discs of 10mm thick and 390mm diameter. Tips : single and multiple flame orifices. Testing items : (1) Characteristic test of torches; the relation between the length of inner core and the pressure and flow quantiity of gas. (2) Heating capasity of the respective parts of the flame. (3) Quenching characteristics ; influence of the orifice diameter, gas flow and gas velocity on the shape and size of the quenched volume. (4) Diameter and distance of orifices to get an uniform depth of quenched part. (5) Influence of travelling speed of flame on the depth, hardness. and end effect of hardened layer.
In this report, effects of post heating on mechanical properties of gas weld steel were investigated. The results obtained are as follows. Welds made by continuous welding operation, ; depositing multilayers, were remarkably improved by torch normalizing. Judging from the results mentioned in Report 1-4, the authors recommend to use the clean welding rod made of low carbon steel containing 1.3-1.5% Mn and 0.1-0.3% Si to obtain excellent weld for mild steel. Very good welded joints are obtained by using above mentioned welding rods and adopting the following welding conditions: 1) Dissolved acetylene and neutral flame, 2) Comparatively large diameters of rod and nozzle, 3) To deposit layers not exceeding about 5mm in thickness, 4) To have each layer cool in still air at some intervals, 5) Backhand and weaving techniques for thicker plates. The low-carbon steel welding rods containing about 1, 6-1, 8 % Mn and 0, 1-0, 3%Si appear to be high tensile suitable for high tensile steels.
In the spot welding of super duralumin sheets, some experiments have been performed under various pressure. And we have discovered that temperature rise is affected not only by contact resistance, but also by the deformation of welded parts during temperature rising. Then by using the variable type pressure ye also have discovered interesting properties of electrode pressure on temperature rise.
In order to investigate the effect of Mo for the low temperature brittleness, the mild steel deposited metals (low hydrogen) containing up to 0.28 % Mo are used. Charpy impact test are carried out in the temperature range of -70°C-100°C. The transition temperature raises in the range.of 0-0.12% Mo, then lowerizes in the range of 0.12-0.28%o Mo. About thes phenomena and the shape of Energy/Temperature curves some dislocational considerations are persued.
In order to control the residual stress and distortion of welded joints, various welding methods such as symmetry, .step back, skip method etc. are used in actual works. In this report, we compared each other the residual stress distributions of the joints welded by these methods. In most case the joints of actual structure are welded under constrained state, and so the determination of welding sequence is one of the most important problems in actual works. In this repot, we used the constrained specimen as shown in Fig. 1, and discussed the effect of welding sequence on the residual, locked-in and weld stresses. For the sake of convenience, we call these experiments "Test I" and "Test II" respectively. Material used is SS 41 steel plate. The specimens in "test I" are 500×200×6 mm bead-welded specimens, 500×100×6mm and 500×100×19mm butt-welded specimens, which, are welded along the 500 mm edge. The welding methods and conditions are shown in Table 1. In "test II", we used the three welding sequences shown in Fig. 2. The residual stresses were measured by SR-4 strain meter. In "Test II" the locked-in stresses were at first measured by cutting the chain line in Fig. 1 and next the residual stresses were measured by usual trepanning method. The results of the tests are shown in Figs. 3, 4, 5, 7 and 8. Fig. 6 shows schematic diagram of the residual stress distribution of bead-welded plate. This diagram was obtained by simple stress analysis. We compared this diagram with the experimental results, and discussed the effect of welding methods and welding sequences. The distributions of residual stress in test I agree in most case with the schematic diagram, Fig .6, but the result of specimen A-4 (skip method) is a little different. In this specimen, transverse stress increases in spite of the decrease of longitudinal stress, and the peaks of residual stress are produced at the last bead. In test II, stress distributions are a little different from the schematic diagram. This difference is due to the disturbance of external constraint and the cross point of welded joint. At last we discussed which method and sequence is favorable from the view point of residual stress distribution. We adopted maximum stress and triaxial ratio as the criterion of comparison, where triaxial ratio is defined by |σ1+σ2+σ3|/3|σmax|. (σ1, σ2, and σ3 are principal stresses and σmax is maximum principal stress.) The maximum stress values and triaxial ratios are shown in Table 2 and 3. From these results we concluded as follows : (1) In the case that the thin plate is welded by one pass, skip method gives comparably small residual stress, but for thick plate welded by multiple pass, cascade block method is most favorable from the view point of residual stress distribution. (2) In constrained specimen, it is favoured to weld at first the shorter joint (for example vn and 'p'Y in specimen "D") before welding longer joint (for example gg' in specimen "D").
The transition temperatures of butt weld joints with internal defects were investigated with specimens, the dimensions of root face (G) and reinforcement (δ) of which were changed in series. Experiments showed that the changes in dimensions of G and δ affected the transition temperatures of butt joints (Fig. 8). Supposing that the degree of geometrical constraint might be anticipated by the difficulty of the growth of plastc ranges originating from ends of G, and this difficulty would be proportionate to the yielding stress of the specimen, tensile tests were made to investigate stress-strain relations by specimens of Fig. 9, and the results as in Fig. 11 were obtained, in which the yielding state was defined by the intersection of two curves, A and B. Then, the effectiveness of the reinforcement under tensile load was calculated on the Neuber theory for semi-infinite plate with a slight projection to correct the nominal sectional area of the specimen. Using thus determined sectional areas, the yielding stress values of the specimen could finally be decided. It was proved that the fracture transition temperatures of joints were raised as the combinations in dimensions of G and S increased the values of σ'yω, (Fig. 14).