ABSTRACT
When welding is conducted in the vertical position, the profile of the weld toe tends to be finished rougher than for the flat position. The strain concentration factor for the press formed RHS consequently tends to be larger than for the welded RHS when vertical welding is adopted. Figure 6 shows the macrographs of the profile of these welded joints. As shown in this figure, the radius r = 7 mm and the flank angle e = 18 deg. were observed for specimen No.12( welded in the flat position ), while r = 1.5 mm and e = 39 deg. were observed for specimen No.13 which was welded in the vertical position. It is therefore preferable to control the heat input in adequate range or to finish the weld toe smoothly in order to prevent the brittle fracture of press formed RHS. As for the strain concentration in weld toe, the roll formed RHS is less than other RHSs,Kamura, H.(1993). Moreover, the buckling phenomenon governs the maximum strength of roll formed RHS. Due to these two reasons, roll formed RHS did not show any fractures from weld toe.
