Laser surface hardening: a review

Abstract
Laser surface hardening (LSH) is one of the most widely used surface hardening process which can be applied to almost the whole range of metallic materials in today's applications. Laser beam is focused to the localised region for hardening the required portion of the material. High intensity laser radiation is involved for heating the surface of steel into the austenitic region. Steep temperature gradient arises, due to high rates of heat transformation that results in instant cooling by conduction. It causes the phase conversion from austenite to martensite without the need for external quenching. Among various types of lasers, CO