| 摘要 |
PROBLEM TO BE SOLVED: To uniformize the mechanical properties and the structure of a steel strip to be treated, at the time of welding a stainless steel strip to a plain steel dummy material and then applying continuous annealing, by controlling furnace temp. on the basis of the differences of heat absorptivity and emissivity between the stip and the dummy material at the time of passing the jointed part through the furnace. SOLUTION: A stainless steel strip, jointed to a dummy material, is annealed. When the set furnace temp. is adjusted to a proper temp. for the stainless steel strip and held constant as in a straight line 6 at this time, furnace temp. temporarily rises as in a curve 8, at the time of transfer from the dummy material to the stainless steel strip by plate feeding, and during the time interval until when conforms to the set value, from the difference of heat absorptivity between the dummy material and the steel strip, the temp. of the steel strip changes as in a curve 2 by the difference of emissivity and temporarily falls below the permissible temp. and, as a result, an incompletely annealed part is produced. Therefore the set furnace temp. is controlled so that it is higher, as in a curve 5, by (α) deg.C at the time of the passing of the dummy material than that at the time of the passing of the stainless steel strip and lower by (α) deg.C at the time of the change to the steel strip. By this method, the furnace temp. and the steel strip temp. can be changed as in a curve 7 and a curve 1, respectively, and the steel strip can be annealed in a proper temp. range over the whole length.
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