The microstructure of the tube blank before and after welding was observed.Three rolls cold rolling with three passes was carried out,and the solution treatment was carried out between the passes.The results show that the weld microstructure is columnar dendrite microstructure;after cold rolling and solid solution treatment,the welding position on the pipe has been difficult to distinguish,and the original weld microstructure is completely transformed into homogeneous microstructure;after three-roller rolli...