溶接基本接手の收縮及び残留応力について : 第1報棒径, 溶接方向, 運棒法, ピーニング, 溶接棒の種類が横収縮に及ぼす影響

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This report is the first part of serial experiements which are being made to survey the effects of welding procedures on the shrinkage, distortion and residual stress of welded joint. The effects of the diameter of the electrode, direction of welding, weaving motion, peening, type of electrode and the degree of constraint on the transverse shrinkage of constrained butt joints are studied in this thesis.The type of specimen used here is the ring form (Fig. 2-1) somewhat different from those utilized so far. This type of specimen is used for the facility of analysing the closing motion of the plate edges during the progress of welding and the distribution of residual stress.Five serieses of experiment were performed using the 7 types of specimen. The experimental conditions for each series are listed in Table 2-2.The measurement of shrinkage were performed at each layer of welding. The results obtained are summarized as follows : -1) The mean shrinkage There exists a linear relation in the multiple layer welding, between the mean shrinkage u^^- and the logarithm of the rod consumption per the unit weld length w which is directly related to the sectional area of the deposit metal, namely : -u^^-=u^^-_0+b(log w-log w_0)where, u^^-_0 : mean shrinkage at the welding of the first layer w_0 : rod consumption per the unit weld length at the welding of the first layer b : physical constant determined by the type of specimen, welding procedures and other conditions.The effect of welding procedures on the transverse shrinkage were investigated by the above equation touching upon the mechanism of shrinkage. The main results are as follows : -(i) Effect of rod diameter The shrinkage decreases with the increase of rod diameter. But the benefit of using the larger electrode to minimize the shrinkage seems to be determined at the welding of the first layer.(ii) Effect of weaving motion and peening The weaving bead method seems to produce the less shrinkage than the stringer bead method. The peening decreases the shrinkage.(iii) Effect of type of electrode The low hydrogen type electrode has produced a large shrinkage.(iv) Effect of degree of constraint Shrinkage becomes smaller with the increase of the degree of constraint, if the weld length is equal ; but the shrinkage seems to become larger with the increase of weld length even when degree of constraint is equal.(v) Submerged arc welding Submerged arc welding produces much less shrinkage-namely 1/3-than the hand-welding.2) Form of Shrinkage The shrinkage due to welding is not uniform along the weld line. As the form of shrinkage is nearly linear, the shrinkage was investigated as the combination of uniform shrinkage and the rotation. Dimensionless parameter α defined by (3) is used for the analysis of the form of shrinkage.The rotational component in the shrinkage α is nearly equal to 1 at the first layer when welding has been done from the inner circle to the outer one. In the first layer, therefore, pure rotation rather than shrinkage occurs. The value of α gradually decreases after the second layer and sometimes begins to increase at the final stage.On the other hand, when welding is made from the outer circle, the value of α is nearly equal to -1 at the first layer, but it becomes about zero at the second layer, and the value of α becomes positive and nearly equal to the one obtained in case of welding from the inner circle after the 3 rd layer.However, even in these cases, when the tack welding are performed at the opposite side before the welding, uniform shrinkage will be obtained as the rotational motion of the plate edges is prevented by the tack welding.The case is quite different with the submerged arc welding. When welding is performed from the inner circle, α is always negative and becomes more negative at the second layer. On the other hand, when welding is done from the outer circle, α increases at the second layer.3) Importance of the First Layer The first layer has a
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溶接基本接手の收縮及び残留応力について : 第1報棒径, 溶接方向, 運棒法, ピーニング, 溶接棒の種類が横収縮に及ぼす影響

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溶接基本接手の收縮及び残留応力について : 第1報 棒径, 溶接方向, 運棒法, ピーニング, 溶接棒の種類が横収縮に及ぼす影響

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溶接基本接手の收縮及び残留応力について : 第1報棒径, 溶接方向, 運棒法, ピーニング, 溶接棒の種類が横収縮に及ぼす影響