Tailoring and testing of novel work roll developments for the early finishing stands of hot strip mills (WORODEFS) : final report

This project aimed to improve work roll performances in early finishing stands, by integrating process conditions and roll shop measurement techniques into the roll grade development. A validated methodology to produce roll grade samples at laboratory scale with similar properties as the shell of a spuncast industrial roll, has been used to produce >30 test blocks of various novel alloys. Rapid development and fine-tuning of novel roll grades, such as either low-friction or high-performance HSS alloy varieties, were enabled by a multi-technique approach, combining detailed microscopic analyses by optical microscopy and SEM+EDX+EBSD with measurements of thermo-physical and mechanical properties. In-service behaviour has been evaluated at laboratory scale by dedicated thermal fatigue tests, fire-crack resistance tests and oxidation tests. The most promising novel roll grades were tested in two series (four campaigns) of pilot mill hot rolling trials, for which a tailor-made NDT system has been built. Meanwhile, an overall roll stress model has been developed, combining thermal, mechanical and residual stress components. Ten documented case studies on industrial rolls with defects/damage served as input for the development of a next generation roll inspection system, with novel NDT sensors for improved detection of cracks in rolls. Two of the most promising alloys, including a new low-friction "Hi-Mo HSS4" grade, were successfully scaled up to full-size rolls for trialling at Tata Steel's DSP mill in IJmuiden with a promising outlook. A third high-performance "Hi-V HSS5" grade is also showing a good potential for industrialization.