Controlling the grain size in hot deformed pipes of stable austenite steel

The possibility is studied of obtaining the austenite grain in the 03Kh20N16AG6 steel not larger than No 4 by the scale GOST 5639-65 in rolled tubes 245x17 mm in size. Small single deformations characteristic for the rolling with the automatic mill 400 contribute to the non-uniformity of deformation distribution over the tube wall cross-section which leads to the non-uniform further recrystallization process and formation of different grains. The presence of the remainder of the cast structure as well as the coarse-granularity of original blank aggravate the different granularity, for concurrent with the recrystallization the polygonization proceeds with the formation of No 1-2 austenite grains which do not undergo transformations in the further thermal treatment. The obtaining of the required structure (with grain size not larger than No 4) in hot-deformed tubes of the 03Kh20N16AG6 steel is possible only providing the fine-granular tube blanks without remainder of the cast structure are supplied. (author)