Study on details of a new welding procedure that had good fatigue strength

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Boxing fillet weldments are found in many parts of a ship's structure. Both fatigue strength and the welding procedure of boxing fillet weldments are primary concerns of ship builders.Fatigue tests and FEM stress analysis were performed for specimens with boxing fillet welded attachments of four different end-conditions : conventional boxing fillet weldment (continuous round fillet weld) and three new types of boxing fillet weldment with different end-conditions (non-continuous round fillet weld). Conventional weldments were made by two welding processes : manual arc and C02 semi-automatic welding, and two welding positions : flat and a combination of horizontal and over-head position and new weldments only by C02 semi-automatic welding and flat position. Fatigue tests were both load controlled axial loading type (non-load carrying type), and a combination of shear and bending loading type (load carrying type). The influence of both the end-conditions and welding procedures on fatigue strength of the boxing fillet weldments have been examined.The main points are as follows :1) The configuration of the weld bead varies depending upon both the welding process and position, and it slightly influences the fatigue strength of boxing fillet weldments.2) For the fatigue tests of non-load carrying type, the three new type boxing fillet weldments (non-continuous types) exhibit at least the same fatigue strength as the conventional boxing fillet weldment (continuous type).3) For the fatigue tests of load carrying type, new type boxing fillet weldments, overrun type, show a little lower fatigue strength than that of conventional boxing fillet weldments.4) The overrun type of boxing fillet weldment is applicable to wet areas provided that the contact surfaces of the welded members are entirely closed with weld bead.