Control of strain and temperature distribution in the ring rolling process

Abstract

When rolling rings on radial-axial ring rolling mills using conventional rolling strategies, strain distribution is greatly non-homogeneous. Due to the constant deformation of the spread bulges, strain peaks are found in the cross section corners. This causes severe problems when rolling strain or temperature sensitive materials. In the case of titanium alloys the strain concentration in the corners leads to overheating in these areas and subsequent microstructure damage and form defects. A new rolling strategy was developed to even the strain distribution by decreasing the cross section areas in just one roll gap at a time, thereby reducing the deformation of the corner material. The new strategy has been tested in industry while rolling TiA16V4-rings conventionally and according to the new strategy. It showed, that severe microstructure damage and form defects that occurred when rolling conventionally are completely avoided and that the ring temperature is homogenised when applying the modified rolling strategy.