High-Power Diode Laser Surface Transformation Hardening of Ferrous Alloys

Abstract

A high-power direct diode laser (HPDDL) having a rectangular beam with a top-hat intensity distribution was used to produce surface-hardened layers on a ferrous alloy. The thermal conditions in the hardened zone were estimated by using numerical simulations and infrared (IR) thermography and then referred to the thickness and microstructure of the hardened layers. The microstructural characteristics of the hardened layers were investigated using optical, scanning electron and transmission electron microscopy together with X-ray diffraction. It was found that the major factor that controls the thickness of the hardened layer is laser power density, which determines the optimal range of the traverse speed, and in consequence the temperature distribution in the hardened zone. The increase in the cooling rate led to the suppression of the martensitic transformation and a decrease in the hardened layer hardness. The precipitation of the nanometric plate-like and spherical cementite was observed throughout the hardened layer.

Microstructure and Mechanical Properties of Sc-Modified AA2519-T62 Laser Beam Welded Butt Joints

“…In some cases (e.g. ferrous alloys), the high density of energy allows to influence the microstructure of processed materials in a profitable way [6]. When it comes to aluminum and its alloys one of the most serious obstacles in laser beam welding is the problem of welds porosity.…”

The Comparison of the Effects of Nodular Cast Iron Laser Alloying with Selected Substances

“…Modifying the surface layer by heating with a laser beam is a method of improving the surface properties of a material, and it is a method that has been advancing since the end of the last century [ 1 ]. Laser processing allows significant changes in the microstructure and properties of local surface areas, including cast iron [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. It is noteworthy that in the case of laser processing, the conditions for microstructure formation are completely different compared with conventional hardening methods.…”