Bainitic steel grade for solid wheels: metallurgical, mechanical and in-service testing

Paper i proceeding, 2007

Bainitic steel grades generally have superior rolling contact and thermal fatigue resistances, but poorer wear characteristics as compared to “conventional” pearlitic steel wheels. To improve wear characteristics the manufacturing process of bainitic materials needs to be carefully controlled. In the current paper, the manufacturing process of the “MICRALOS” bainitic steel grade is described. The main focus is on metallurgical testing activities performed in order to compare the new steel grade to standard pearlitic steels and to predict service behaviour of the solid bainitic wheels. Further, on-going field tests on the iron-ore line between Luleå and Narvik are reported, with details about measurement methods and results. The performance of the wheels is reviewed and compared to the current scientific knowledge of bainitic steel grades and the deterioration of heavy haul wheels. Finally benefits of, and challenges for bainitic wheels in general and for the MICRALOS grade wheels in particular will be discussed.