LABORATORY TESTING AIMED AT THE DEVELOPMENT OF MATERIALS FOR HOT ROLLS

摘要

The performance of rolls used in hot strip rolling depends on a large number of factors that, in most cases, are very difficult to be rationalized. The results from the mill plants are often not comparable, being based on subjective feeling rather than on scientific parameters. So it is quite usual to get very different performance figures for the same roll grade on different mills. Moreover, field tests are expensive and imply a risk that is not accepted by most customers, so that the introduction of new experimental grades is a very complex task. For all these reasons big efforts have been made in the last years to reproduce the in-service behaviour of hot mill rolls by means of laboratory tests. Damage phenomena like wear and thermal fatigue have been reproduced by means of customary equipment by several universities and research centres. In this way, the consolidated cooperation between INNSE Cilindri, one of the most important European roll-makers and University of Trento has led to the investigation of the principal causes for roll failure and/or deterioration and their correlation with the microstructure of roll materials. It is the goal of the present paper to analyse the use of laboratory testing in the development of materials for hot mill rolls, from the roughing to the finishing stands. The general approach used was to investigate separately the material behaviour with respect to each one of the damaging phenomenon cited above. This is quite different from what occurs in real rolling, where their superimposition often hampers a correct evaluation of the influencing factors. In many cases, the experimental results are in good agreement with those obtained in industrial practice, as confirmed by the data reported in the paper.