|M.Sc Student||Klachuk Shahar|
|Subject||Structure and Properties of 1045 Steel Surface Laser|
Alloyed with 50%Wt Ni-50%Wt CrB2
|Department||Department of Materials Science and Engineering||Supervisor||Professor Emeritus Menachem Bamberger|
|Full Thesis text - in Hebrew|
Laser surface alloying is a process whose purpose is to improve the surface properties by incorporating alloying elements into the surface. The advantages of using laser for surface treatment are: formation of a non-equilibrium or amorphous phase as well as homogenization and refinement of the microstructure, all without affecting the substrate properties.
Powder (50%Wt Ni- 50%Wt CrB2) was injected into a melt pool created by a CW-CO2 laser on AISI1045 steel plates. In order to alloy the entire surface, the sample was scanned at scan speeds in the range of 600-6000 mm/min and the laser power was in the range of 1750-2500W. The powder feed rate was 1.6 gr/min, the laser beam was 2mm in diameter, with 60% overlap between successive laser paths.
Metallographic cross-sections were made of the samples. For each sample the following properties were characterized: layer depth, micro-hardness (Hv), layer microstructure and composition.
It has been found that the scan speed and the laser power affect the depth of the melt pool, the microstructure, the hardness and the treated layer composition. The laser boronized surface exhibits better wear resistance than D2-tool steel hardened to 59±1 Rc. This will be discussed based on numerical analysis of the laser/material interaction.