1. Technical Principles and Core Advantages

Laser hardening technology uses a high-energy-density laser beam as the heat source. The laser beam, generated by a laser system, is transmitted and focused through a precise optical system to form a high-energy density spot, enabling accurate heat treatment on the surface of the metal substrate. This process significantly outperforms traditional methods such as flame hardening and medium- and high-frequency induction hardening, mainly due to the precise control of laser beam energy. The shaped laser beam possesses unique characteristics such as high energy density and excellent directionality.

2. Basic Process Features

1. Ultra-High Surface Hardness

The surface hardness after laser hardening is significantly higher than that of conventional hardening processes, with hardness increases ranging from 5% to 20%. This significant hardness enhancement is primarily due to the fine-grained martensitic structure formed during the rapid heating and cooling process of the laser.

2. Precise Control of Hardened Layer

• Effective hardened layer thickness: controllable in the range of 0.2-1.0mm
• Single hardened band width: ranging from 1.5 to 60mm
• Multi-pass overlapping treatments are supported, enabling uniform hardening over large areas.

3. Minimal Heat Affected Zone and Deformation

The heat-affected zone (HAZ) at the interface between the hardened layer and the base material is extremely small, typically ranging from 0.3 to 1.5mm. This localized heat input characteristic effectively controls the overall deformation of the workpiece, making the process particularly suitable for surface strengthening of precision components.

4. Flexible Process Implementation

The working distance between the processing head and the workpiece surface is maintained in the range of 100-300mm, providing ample space for process implementation. This technology supports localized precision hardening and is also suitable for customized heat treatment for complex geometries, showcasing exceptional process flexibility and control.

3. Material Strengthening Mechanism

Laser hardening is one of the key technologies for surface strengthening of materials. During the laser hardening process, the rapid heating and cooling of the laser on the material surface leads to the formation of high-carbon fine plate martensite, high-dislocation density austenite, sorbite, et hard carbides. These microstructures significantly enhance the material’s wear resistance and corrosion resistance, improving the surface properties of the workpiece.

4. Process Parameter Research

Existing research has revealed how changes in laser power and scanning speed during laser phase transformation hardening affect the depth et hardness of the hardened layer. However, research on the factors affecting melt quenching processes is relatively limited. Although some deformation occurs after melt quenching, this process allows for deeper hardened layers, making it highly valuable for applications.

Experimental Design and Methods

Laser melt quenching experiments were conducted using 42CrMo steel, focusing on analyzing how laser power and scanning speed affect the resulting structure and performance. A YLS-3000 fiber laser was used for surface melt quenching, with samples taken from the middle of the treated areas for further analysis.

Materials and Testing

• Matériel: 42CrMo alloy structural steel
• Dimensions: 20mm x 20mm x 11mm
• Base hardness: 310 HV
• Surface roughness: 3.0
• Chemical composition:
  • 0.54% C
  • 1.32% Cr
  • 0.39% Mo
  • 0.45% Si
  • 0.78% Mn
  • Balance: Fe

Testing Methods

• Microstructure of the hardened layer observed using a ZEISS Imager.A2m stereomicroscope et Hitachi S-3400 scanning electron microscope
• Hardness testing using a domestic small-load Vickers hardness tester
• Depth of hardened layer determined using Vickers hardness combined with metallographic images

5. Experimental Results and Analysis

The experimental results indicate that the depth of the hardened layer increases with higher laser power et lower scanning speed, while the depth decreases with lower laser power et higher scanning speed. Among these factors, laser power has a more significant impact on the hardened layer depth. This finding provides an important basis for optimizing process parameters.

6. Conclusion and Greenstone-Tech’s Innovation

Through systematic process research and parameter optimization, Greenstone-Tech continually enhances the performance of laser hardening technology. We provide our customers with precise, efficient surface strengthening solutions to meet the diverse needs of component performance improvement across various industries.