METHOD FOR FORMING DEFORMED CROSS SECTION AND FORMED ARTICLE OF QUADRILATERAL CROSS-SECTION EXCELLENT IN SPOT WELDABILITY

摘要

PROBLEM TO BE SOLVED: To provide a method of obtaining a formed article of deformed cross-section with high dimensional accuracy excellent in spot weldability. SOLUTION: Crushing work is carried out on a tubular material 10 with a tensile strength (TS) of≥690 MPa by a die 1 of deformed cross-section having at least one flat part A1 on the surface thereof in a state that inner pressure is not loaded or in a state that an inner pressure of≤50 MPa is loaded on it by liquid. Subsequently an inner pressure of >50 MPa is loaded by the liquid and the tubular material is formed into a deformed cross-section shape, wherein forming is carried out so as to allow a perimeter increase rate after forming to be≥A% and≤11.0%, where A=4.167×10-3×(TS-590). COPYRIGHT: (C)2010,JPO&INPIT