Novel nano-structured bainitic steels for enhanced durability of wear resistant components: microstructural optimisation through simulative wear and field tests (BAINWEAR)

Abstract

Nanobainitic steels present a very high strength/toughness as a consequence of their extremely fine microstructure. They have also demonstrated potential for wear-resistance applications. The aim of BAINWEAR is to investigate such microstructure-wear mechanisms relationship to develop a new family of bainitic steels with a unique combination of mechanical and wear properties. In this project, four different industrial applications with harsh requirements in terms of wear and contact fatigue have been selected: Mill rollers, Punches for cutting sheet metal, Ball bearings and Reducing elements in a shredder machine. For these applications, the main requirements and damage mechanisms have been investigated and defined. In parallel, work has been performed in characterizing three steel grades with potential to form nanobainitic microstructures. Transformation dynamics, resulting microstructure and mechanical properties have been analysed. After these development, the new materials in different microstructures have been subject to a battery of tests reproducing requirements from the studied applications. The new grades outperformed the standard 100Cr6 in pure contact fatigue conditions, while showing comparable abrasive wear resistance when treated at the same hardness level. Based on the results of these studies, grades were applied on the different industrial applications. Rollers matched the standard roller performance, slightly improving it in selected conditions. Sheet metal punches showed good results, particularly when coated. In bearing application, the new grades outperformed 100Cr6, approaching more expensive material options. Finally, in pure abrasion applications as in reducing elements on a shredder machine, the materials did not increase performance.