溶接基本接手の收縮及び残留応力について

第3報 撓み変形及び残留応力

抄録

This report is the third part of serial experiments which are being made to survey the effect of welding procedures on the shrinkage, distortion and residual stresses of welded joint.
Angular change of welded part, the deflection of specimen due to angular change and residual stresses are studied in this thesis.
The constrained ring form specimens were used. The size of specimen and welding conditions were mentioned in Part I and II.
The measurement of angular change was performed by comparater and dial gauge. The deflection of specimen was measured by dial gauge.
The change of reaction stress during multilayer welding, residual stress and the stress released by slitting along the weld line and by cutting out the weld metal were also measured by electric wire strain gauges.
The main results obtained are summerized as follows:
1) Relation Between Augular Change and Deflection of Specimen
The deflection due to welding is found to be calcurated from the angular change as a problem of elastic dislocation. The relation between angular change φ₁ and deflection δ of ring form joint is shown in equation (2). An example of the value of H(ρ, θ) in equation (2) is shown in Fig. 3-4.
2) Relation Between Angular Change and Weight of Deposited Metal
The relations between angular change and weight of rod consumption per unit weld length for various types of bevel are shown in Fig. 3-5. The angular change mainly increases at the welding of 2nd or 3rd layer. Chipping has little effect on the angular change.
3) Change of Reaction Stress During Multilayer Welding
An example of the change of reaction stress during multilayer welding is shown in Fig. 3-8. The reaction stress can be calcurated from the transverse shrinkage as a problem of Volterra type dislocation.
4) Relation Between Residual Stress and Dislocation
The stress (circumferential strain εθ) released by slitting along the weld line is shown in Fig.3-9. The dislocation due to slitting is shown in Fig. 3-10. The stress distribution calcurated from this dislocation (curve 1'-5') fairly coincides with that of actually measured (curve 1-5). The equations of this calcuration are shown in equation (3) and (4).
The changes of stresses due to slitting, cutting out the weld metal and fine cutting are shown in Fig. 3-11 (a), (b), (c). The curve 3 of Fig. 3-11 shows the residual stress due to welding.
From these experiments it is shown that the residual stress transverse to the weld line seems to be calcurated from the dislocation due to cutting along the weld line as a problem of elastic dislocation of higher order.