To solve a problem of a conventional pipe flattening test method which cannot often provide a correct evaluation value due to high susceptibility of buckling in a heavy flattening region where the flattening level is high.
In the pipe flattening test method, a portion around the center in the longitudinal direction of the pipe is flattened to a predetermined flattening height h while restraining both pipe ends of a test piece 10 of the pipe. The pipe is flattened within a range which satisfies the relation: L1/D=0.5 to 2.0 wherein L1 represents the length of a flattening part which is flattened to the predetermined flattening height h; and D represents the outer diameter of the pipe, and the relation: L2/D=0.5 to 1.5 wherein L2 represents the length of a gradually changing part where the flattening height is gradually changed from the restraining region of the pipe end of the test piece to the flattening part; and D represents the outer diameter of the pipe.
SHINGU TOYOHISA
SONOBE OSAMU
SUZUKI KOJI
