Surface Nanocrystallization Of Hadfield Steel Induced By Strain And Effects Of Abrasive Wear Properties

Surface nanocrystallization is a new concept proposed in recent years. It uses methods such as severe plastic deformation (SPD) to generate a nanostructured surface layer, which can improve the overall properties and behaviours of materials. In this article, a nanostructured surface layer was fabricated on the hadfield steel by means of surface shot peening treatment.By using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution electron microscopy (HREM), field emission scanning electron microscopy (FESEM) and microhardness testing machine to investigate: (1) The microstructure and nanocrystallized mechanism of hadfield steel by means of shot peening treatment;(2) effect on properties of hadfield steel after shot peening treatment;(3) effect on impact wear properties of hadfield steel by means of surface nanocrystallization;(4) effect on two-body abrasive wear properties of hadfield steel by means of nanocrystallization;(5) effect on three-body abrasive wear properties of hadfield steel by means of nanocrystallization.After the surface shot peening treatment, a nanocrystalline surface layer was formed, the average grain size of which is no more than 10nm, and the grain size increases with the increase of depths to the surface. The microhardness of nanostructured surface is enhanced significantly after the shot peening treatment compared with that of the original sample. The deformation layer can be divided into three parts: nanocrystalline layer, sub-microcrystalline layer and transition layer. The nanocrystallized mechanism of hadfield steel is relative to the tangle of high-density dislocation, the reaction and recombination of high-density dislocation, the interaction of twins and dislocation, and the repeating incision of multi-system twins.Study shows that work hardening cannot improve the wear properties of samples significantly under the conditions of impact abrasive wear by using the abrasive ofquartz and two-body abrasive wear in which corundum is the main abrasive, but it can improve the wear properties of samples remarkably, even twice as that of the original wear property at the suitable peening time, after surface nanocrystallization in the conditions of two-body abrasive wear and three-body abrasive wear by using the abrasive of glass. Fatigue wear is the main wear mechanism of three-body abrasive wear by using the abrasive of glass.