Demanded work roll properties for maximum performance in hot rolling of plate (DEMROLL)

Purpose and goal

Damage evolution and roll performance in the plate mill has been studied in industrial trials, demonstrating the advantages of using HSS (High Speed Steel) rolls for longer rolling campaigns. The expected outcome is an increased productivity through longer campaigns in the mill, less material usage, and increased industrial competitiveness for both a roll producer like Åkers but also roll user like Oxelösund. As part of the project, a full-scale 54 tonnes HSS roll has been produced by Åkers and tested in production at SSAB Special steels.

Expected results and effects

Åkers has demonstrated a new production route for HSS rolls. These rolls require certain heat treatments to give the desired microstructure. A new alloying concept has been suggested, and small-scale laboratory ingots have been produced. Experimental validation by dilatometry has been made confirming how alloying can push unwanted phase transformations to longer times and thereby making it possible to produce the HSS plate rolls with existing production facilities. The full scale roll prototype was produced, and tested in industrial trials at SSAB Special Steels.

Planned approach and implementation

The project was carried out according to expectations, to start with alloy design based on current production limitations for HSS rolls, to small scale laboratory work with samples around 200g, to full scale prototype on 54 tonnes. With limited input from literature, existing roll materials were characterized to identify damage mechanisms, which was then used to a micro-FEM code to model damage evolution in these roll microstructures. The roll was produced as a prototype, optimized, and tested in production. The project was prolonged due to extra time needed to test it in production.