抄録
In our previous study, the elongated bead welding with Low Transformation Temperature (L.T.T.) welding material were investigated to apply to boxing fillet welded joints used in ship’s local struc-ture. The welded joints by gas metal arc welding (80%Ar・20%CO2 shielding gas) with LTT1 welding material of 10Cr10Ni filler metal showed sufficient fatigue life enhancing effect.
In this study, we showed that the elongated bead welding with newly developed L.T.T. welding material can enhance the fatigue life of boxing fillet welded joints even under the condition of 100%CO2 gas shielded arc welding. That is, by using newly developed LTTB welding material of 16Cr8Ni flax cored wire, CO2 gas shielded arc welding in all positions can be possible and the repair welded joints by 40 mm elongated bead welding with LTTB welding material showed about 4.3 times fatigue life in the case of overhead position welding and about 10.5 times and more fatigue life in the case of flat position welding compared with that by conventional welding.
In addition, the fracture toughness tests of LTTB weld metal by using the weld metal cen-ter-notched fracture toughness test specimen were carried out. It was shown that LTTB weld metal had sufficient fracture toughness.
As a result, it was shown that a fatigue life enhancing technique simply by in-house welding to re-pair the fatigue crack that generates in boxing fillet welded joints in ship’s local structure can be ap-plied to practical use.
