Abstract
Laser surface hardening is an attractive heat treatment solution used to selectively enhance the surface properties of components by phase transformation. A quantitative parameter to measure the efficacy of hardening processes is still lacking, which hinders its application in industries. In this paper, we propose a simple approach to assess the effectiveness of the process by calculating its thermal efficiency. The proposed method was applied to calculate the hardening efficiency during different laser processing conditions. This study revealed that only a small portion of supplied laser energy (approximately 1–15%) is utilized for hardening. For the same laser system, the highest efficiency is achieved when surface melting is just avoided. A comparative study showed that pulsed lasers are more efficient in energy utilization for hardening than continuous wave laser. Similarly, the efficiency of a high-power laser is found to be higher than a low-power laser and an increase in beam absorption produces higher hardening efficiency. The analysis of the hardened surface revealed predominantly martensite. The hardness value gradually decreased along the depth, which is attributed to the decrease in percentage of martensite.
Highlights
Laser surface hardening is an emerging technique used in manufacturing industries to selectively increase the surface hardness of highly stressed components such as camshafts, crankshafts, brake drums, bearings and gears by phase transformation
A typical laser hardening process is shown in Figure 2 whereby a defocused laser beam beam is utilized to scan over a surface to obtain the hardening effect
A high-power laser system with a large beam spot yields higher hardening efficiency compared to a low-power laser
Summary
Laser surface hardening is an emerging technique used in manufacturing industries to selectively increase the surface hardness of highly stressed components such as camshafts, crankshafts, brake drums, bearings and gears by phase transformation. It produces a hardened wear-resistant outer layer without affecting desirable bulk properties such as toughness and ductility [1]. Despite the progress made in computational modeling and simulation [8,9], experimental trials are still required to select the processing parameters for industrial hardening applications. The main aim is to determine the right laser parameters to achieve superior surface hardness and the desired hardened depth. The availability of a suitable framework would ease the screening process and help in optimization
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