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

在船舶结构的许多部位都发现了装箱角焊。箱体角焊缝的疲劳强度和焊接工艺是造船企业关注的主要问题。对四种不同端态的盒形角焊附件试件进行了疲劳试验和有限元应力分析：传统盒形角焊件（连续圆角焊）和三种不同端态的新型盒形角焊件（非连续圆角焊）。常规焊缝采用手工弧焊和二氧化碳半自动焊两种焊接工艺，焊接位置为平焊和水平与头顶结合的两种焊接位置，新焊缝仅采用二氧化碳半自动焊和平焊位置。疲劳试验分为受载荷控制的轴向加载型（非承载型）和剪切弯曲组合加载型（承载型）。研究了端部条件和焊接工艺对箱体角焊缝疲劳强度的影响。其要点如下：1)焊头的结构随焊接工艺和位置的不同而不同，对箱体角焊缝的疲劳强度影响较小。2)在非承载型疲劳试验中，三种新型箱体角焊件（非连续型）的疲劳强度至少与传统箱体角焊件（连续型）相同。3)在承载型疲劳试验中，超限型新型箱体圆角焊的疲劳强度略低于常规箱体圆角焊。4)套筒角焊件的超限型适用于潮湿地区，只要被焊构件的接触面与焊头完全封闭即可。

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.