INVESTIGATION OF VARIATION OF WALL-NONUNIFORMITY,MICROSTRUCTURE AND PROPERTIESOF HOME-MADE J55 HI-FREQUENCY STRAIGHT WELD PIPE IN COLD-DRAWING （ROLLING） DEFORMATION

Based on the experiments in deforming with cold-drawing （rolling） process and heat treatment of J55 hi-frequency straight weld pipe,the optimum deformation range for minimum wall-nonuniformity （u=1.45） has been set up,and the variation of microstructure and properties of the pipe under cold-drawing （rolling） conditions measured. The experimental result shows that with single-pass cold-rolling under proper control of deformation amount,it is possible to produce finished precision weld pipes with wall-nonuniformity under 3% and properties equal to or better than those of the 20^# precision steel pipe for pump service.