Laser hardening of boring tools

During many manufacturing processes for surface treatment of steel components heat will be exchanged between the environment and the workpiece. The heat exchange commonly leads to temperature gradients within the surface near area of the workpiece, which involve mechanical strains inside the material. If the corresponding stresses exceed locally the yield strength of the material residual stresses can remain after the process. If the temperature increase is high enough additionally phase transformation to austenite occurs and may lead further on due to a fast cooling to the very hard phase martensite. This investigation focuses on the correlation between concrete thermal loads such as temperature and temperature gradients and resulting modifications such as changes of the residual stress, the microstructure, and the hardness respectively. Within this consideration the thermal loads are the causes of the modifications and will be called internal material loads. The correlations between the generated internal material loads and the material modifications will be called Process Signature. The idea is that Process Signatures provide the possibility to engineer the workpiece surface layer and its functional properties in a knowledge-based way. This contribution presents some Process Signature components for a thermally dominated process with phase transformation: laser hardening. The target quantities of the modifications are the change of the residual stress state at the surface and the position of the 1st zero-crossing of the residual stress curve. Based on Finite Element simulations the internal thermal loadings during laser hardening are considered. The investigations identify for the considered target quantities the maximal temperature, the maximal temperature gradient, and the heating time as important parameters of the thermal loads.

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Time-dependent 3D modeling of the thermal analysis of the high-power diode laser hardening process

Optics & Laser Technology ◽

10.1016/j.optlastec.2020.106216 ◽

2020 ◽

Vol 128 ◽

pp. 106216 ◽

Cited By ~ 1

Author(s):

Saeed Talesh Alikhani ◽

Mohammad Kazemi Zahabi ◽

Mohammad Javad Torkamany ◽

Seyed Hasan Nabavi

Keyword(s):

Thermal Analysis ◽

Diode Laser ◽

High Power ◽

3D Modeling ◽

Laser Hardening ◽

Time Dependent ◽

Hardening Process ◽

Power Diode ◽

High Power Diode Laser

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A New Computationally Efficient Model for Tempering in Multi-Tracks Laser Hardening

ASME 2009 International Manufacturing Science and Engineering Conference, Volume 2 ◽

10.1115/msec2009-84093 ◽

2009 ◽

Cited By ~ 3

Author(s):

Alessandro Fortunato ◽

Leonardo Orazi ◽

Giovanni Tani

Keyword(s):

Process Parameters ◽

Laser Power ◽

Laser Scanning ◽

Original Model ◽

Laser Hardening ◽

Computationally Efficient ◽

Laser Process ◽

Treat All ◽

Tempering Time ◽

Experimental Comparisons

The bottleneck in laser hardening principally occurs when large surfaces have to be treated because this process situation leads to multi-tracks laser scanning in order to treat all the component surface. Unfortunately, multi-tracks laser trajectories generate an unwanted tempering effect that depends on the overlapping of two close trajectories. To reduce the softening effects, a simulator capable to optimize the process parameters such as laser power and speed, number and types of trajectories, could sensibly increase the applicability of the process. In this paper an original model for the tempering is presented. By introducing a tempering time factor for the martensitic transformation, the hardness reduction can be predicted according to any laser process parameters, material and geometry. Experimental comparisons will be presented to prove the accuracy of the model.

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