Local hardening technology for metal parts--laser quenching

In modern manufacturing, improving the surface hardness and wear resistance of metal materials is the key to improving product performance and life. Traditional quenching technologies, such as salt bath quenching and induction quenching, can effectively improve the overall hardness of the material, but it is often difficult to achieve precise local hardening. The emergence of laser quenching technology, with its unique advantages, provides a new solution for local hardening and is widely used in customer-customized hardware parts and injection molds.

Laser quenching is a quenching technology that uses laser to heat the surface of metal materials to above the phase transition point. As the metal material cools itself, austenite transforms into martensite, thereby hardening the surface of the material. It has high heating and cooling speeds, short process cycles, and does not require external quenching media. It has unique advantages such as small workpiece deformation, clean working environment, no need for finishing such as grinding after treatment, and the size of the processed gear is not limited by the size of the heat treatment equipment.


Laser quenching has high power density, fast cooling speed, and does not require cooling media such as water or oil. It is a clean and fast quenching process. Compared with induction quenching, flame quenching, and carburizing quenching processes, laser quenching has a uniform hardened layer, high hardness (generally 1-3HRC higher than induction quenching), small deformation of the workpiece, easy control of the heating layer depth and heating trajectory, and easy automation. It does not need to design corresponding induction coils according to different metal part sizes like induction quenching, and the processing of large hardware parts does not need to be limited by the furnace size during chemical heat treatment such as carburizing quenching. Therefore, it is gradually replacing traditional processes such as induction quenching and chemical heat treatment in many industrial fields. It is especially important that the deformation of the workpiece before and after laser quenching can be almost ignored, so it is particularly suitable for the surface treatment of customized hardware parts with high precision requirements.

The depth of the laser hardened layer is generally between 0.3 and 2.0 mm, depending on the composition, size and shape of the customized parts and the laser process parameters. The tooth surface of large gears and the journal of large shaft parts are quenched, and the surface roughness remains basically unchanged, and no subsequent machining is required to meet the needs of actual working conditions.

Laser quenching technology is widely used in mechanical processing industry, petrochemical industry, medical industry, aerospace industry, automobile parts manufacturing factory, etc. It can be used to strengthen the surface of various guide rails, large gears, journals, cylinder inner walls, molds,  friction wheels, rollers, and roller parts. Applicable materials are medium and high carbon steel and cast iron.

Gears are widely used parts in the machinery manufacturing industry. In order to improve the bearing capacity of gears, the gears need to be surface hardened. However, traditional gear hardening processes, such as surface chemical treatments such as carburizing and nitriding, induction surface hardening, and flame surface hardening, have two main problems: large deformation after heat treatment and difficulty in obtaining a hardened layer evenly distributed along the tooth profile, which affects the service life of the gear.