| 摘要 |
<PICT:1089701/C6-C7/1> Silicon steel sheet or strip e.g. containing 1-4% Si is heat treated by pre-heating it, e.g. moving a strand 9 of the steel from a coil 6 held on turn-table 4 in an entrance housing 1, through an elongated pre-heating furnace A, to above 900 DEG C. without subjecting it to the temperature range 800-900 DEG C. for more than 10 minutes, and then annealing it, e.g. in coiled form reeled on to spindle 22 on platform 23 carried by turn-table 24 in a bell furnace B, in two stages: first at 950 to 1050 DEG C. for at least 1 hour (for yielding optimum grain growth) and second at 1100 to 1200 DEG C. for a least 1 hour (for purification e.g. removing S during secondary recrystallization). Furnaces A and B fitted with heating elements 13, 30 may be removably connected to each other e.g. at housings 32 and 31 sealed by a gasket 33. The reeling may be started by a switch 29 which starts a drive train (not shown) which synchronously drives vertical rollers 7, 12 and 21 (by motor 35) and turn-table motors 4a and 25. The furnaces are preferably purged with N2 and then filled with H2 prior to reeling. The annealed coiled steel may be also cooled in H2 e.g. to 500 DEG C. within the furnace B. |
