On the basis of the practical structure of O section flux-cored wire,the effects of overlap edge of steel strip on arc profile and droplet transfer mode were given in detailed formulation.

Manufacturing hub by cold bending special section profile can be considered as the problem of special section plate bending,which is nonlinear in physics and geometry.

In the welding construction of the main tower at stage A of the World Trade Center phase Ⅲ,some difficulties were settled,inclusive of deformation control in welding the huge cross-section column,welding super long seam in the steel plate wall,inclined welding and thick plate welding at minus temperature as well as welding of suspended truss etc.