Properties of electron beam hardened layers made by different beam deflection
The usage of the high-energetic source electron beam enables repeated surface quenching of chosen areas of an engineering part surface. Different techniques of electron beam deflections allow the creation of hardened layers of different shapes and above all thicknesses. Experiments were carried out on material 42CrMo4 (1.7225) and one point, seven points, eleven points, line, field and meander were tested deflection. Influence of process speed and defocusing of the electron beam was studied Properties of layers were compared with induction hardened layers. The electron beam surface quenching resulted in a very fine martensitic microstructure with the hardness over 700 HV0.5. The thickness of the hardened layers depends on the type of deflection and depends directly (except field deflection) on process speed. The maximum observed depth was 1.49 mm. Electron beam defocusing affects the width of the hardened track and can cause extension of the trace up to 40%. The hardness values continuously decrease from the surface to the material volume.