heating {HEAD ~ the steel sheet} 7 to {TAIL ~ a temperature range} from an Ac3 transformation point to 1000° C.; and 
heating { HEAD ~ the steel sheet } 7 to { TAIL ~ a temperature range } from an Ac3 transformation point to 1000 ° C. ; and
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH