Parametric Impact on the Microstructure and Wear Behavior of Laser Surface Alloyed Iron Boride Layers

摘要

Laser surface alloying (LSA) is increasingly recognized as a powerful surface modification tool for meeting the surfacing objectives to combat wear, corrosion, oxidation, etc. A particularly promising application of LSA involves surface alloying of boridcs to develop an insulating hardfacing which can impart enhanced thermal and mechanical properties to components which operate in erosive/abrasive and high temperature environments. This route can also potentially eliminate the adverse effects of the conventional thermochemical boronizing treatment on the structure and the properties of the bulk. The present study concerns laser surface alloying of medium carbon steel with Fe_2B using a high-power CO_2 laser. The influence of laser power and scan speed, as well as the number of repetitive scans, on microstructural features and other aspects such as phase constitution, depth of alloyed zone and heat-affected zone was comprehensively investigated. Hardness profiles were determined in the alloyed layers, as well as hardness variations between different microstructural features measured using nano-indentation techniques, to get additional insight into alloy formation by the LSA process. The wear performance of the alloyed layers were also evaluated under abrasive wear conditions and compared with that of the bare substrate.