To manufacture an austenitic stainless steel seamless tube by on-line solution heat treatment.
After heating a billet of austenitic stainless steel, hot piercing and successively executing finish rolling (elongating work + finishing work) in which average strain rate determined by the under-mentioned equation is ≥0.01/sec and the compressibility of cross section is ≥10% at finished temp. of 800-1050°C, immediately the billet is reheated to 1000-1150°C, held for 10sec to 30min and next, cooled at a cooling rate of ≥1.5°C/sec from the temp. of ≥900°C. The average strain rate = (the working strain in the elongating work + working strain in the finishing work)/(the time from the start of the elongating work to the completion of the finishing work at the tip of a hollow tube stock).
KONDO KUNIO
TANIMOTO SEIJI
ABE TOSHIHARU
Next Patent: PLUG DEVICE FOR PIERCING SEAMLESS STEEL TUBE