| 摘要 |
PURPOSE:To decide the acceptance or rejection of the heat treatment characteristics of steel pipes by nondestructive inspections by deciding whether the coeffts. of expansion of the outside diameters of the steel pipes produced before and after hardening satisfy target control coeffts. of expansion or not. CONSTITUTION:This is a method of deciding the hardening characteristics of steel pipes by nondestructive inspections on-line in pipe making stages. The outside diameters of a steel pipe produced before and after hardening are defined as Da, Db, respectively. The target coefft. of pipe expansion determined by the expression II from the coefft. of expansion; Da-Db/Db thereof, ideal limit; Di, plate thickness; (t) and hardening temp.; T is defined as alpha, and the control limit value determined by selection of production conditions as S. The acceptance or rejection of the heat treatment characteristics of the steel pipe is determined from whether these numerical values satisfy the equationIor not. Namely, if the coeffts. of expansion are within this range, that steel pipe is accepted. |
