| 摘要 |
PURPOSE:To bend a steel pipe to have the uniform strength after bending by heating the steel pipe to the temp. above the A1 transformation point and bending the steel pipe. CONSTITUTION:Hot bending of a steel pipe is accomplished by heating the steel pipe within the range where the A1 transformation point in the phase diagram of steel or below or the temp. lower by 50 deg.C than the A1 transformation temp. is made the upper limit temp. and the recrystallization temp. of the steel is made the lower limit temp. and bending said pipe. The heating temp. distribution from the bent part of the steel pipe to the straight pipe part which is not bent is then made the temp. distribution from the annealing temp. to a room temp. Thus the part where the temp. is above the A1 transformation temp. and just below the A3 transformation temp. does not exist and therefore the uniform strength is obtd. to the steel pipe after bending and cooling. |
