Martensitic stainless steels are widely used in many industrial engineering applications such as steam and water valves, pumps, screw machining parts, turbines which require high strength and high resistance to wear and corrosion. Failure of such stainless steel components due to corrosion, fatigue and abrasion, erosion is most likely to initiate from the surface. The engineering solution for minimizing or eradicating such surface-initiated failures lies in tailoring the surface composition and/or microstructure of the near surface region of a component without affecting the bulk. In recent years, application of laser surface modification to prolong the service life of the engineering components is one of the most promising techniques for improving the surface properties of the majority of metals. Surfaces can be treated with a laser beam to modify their surface properties. The laser beam subjects the near-surface to a thermal transformation with an amplitude and shape which depends on the process variables: the beam size, energy, scan rate and on whether the laser is pulse or continuous, and the chemistry and metallurgy of the steel. In this study, different laser hardening process parameters (laser power density, travelling speed) effect on hardening depth and hardness of 420 stainless steel are investigated. As a result of the contact of the laser with the surface martensitic transformation takes place. The hardenability is superior to the induction and flame hardening methods.
Anahtar Kelimeler: Surface modification, Laser hardening, Martensitic transformation
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