Laser stelliting: protecting critical components and extending their service life through controlled dilution
In many industrial sectors – valves, nuclear or forging tools – certain components are subjected to extreme conditions: abrasive wear, corrosion, cavitation and thermal shock. To extend their service life, one solution is to apply a coating of cobalt-based alloy, known as stellite, renowned for its resistance properties.
But depositing this type of alloy without degrading the filler material remains a genuine industrial challenge.
An industrial challenge: limiting dilution while industrialising the process
The main obstacle in stelliting lies in substrate dilution, that is, the mixing of the base material – often iron-rich – with the stellite alloy. Excessive dilution alters the desired properties of the coating and reduces or even eliminates the effectiveness of the treatment.
Historically, the process offering the best control of dilution is oxyacetylene flame hardfacing. However, this technique has several major limitations. It requires years of training to master the skill, making such expertise rare today. The sector has also declined sharply over the last decade, notably after nuclear programmes were halted.
Furthermore, this process causes significant overheating, which can degrade the metallurgical characteristics of the substrate. Other automatable solutions exist, such as TIG or PTA, but they struggle to achieve a sufficiently low and stable level of dilution for certain critical applications.
A laser approach combining precision and automation
To meet these constraints, IREPA LASER has developed a solution based on a laser powder deposition cladding process (DED).
The principle involves feeding powder coaxially to a laser beam to create a melt pool. This configuration makes it possible to precisely control heat input and dilution.
IREPA LASER has recognised expertise in this field. Over many years, the company has notably developed and patented a specific coaxial cladding nozzle. It is designed first to melt the powder and then to deliver heat to the substrate, thereby limiting mixing between the two materials.
As technology has evolved, these nozzles have been optimised to suit current laser powers and industrial requirements, now offering a wide operating window and a particularly robust process.
Measurable results for industrial applications
This approach delivers particularly attractive performance for demanding industrial applications.
Substrate dilution can be controlled to between 3 and 5%, a level low enough to preserve the properties of the stellite. This performance makes it possible, in particular, to reduce the number of layers required, thereby cutting processing times and material consumption.
The process also offers further advantages:
- Low thermal impact on the substrate, preserving its metallurgical properties
- Process automation, ensuring better repeatability
- Robust deposits, suited to critical or high-value parts
These characteristics pave the way for more reliable industrialisation of stelliting, while retaining the required metallurgical performance.
A demonstration of IREPA LASER's expertise in laser processes
This type of development illustrates IREPA LASER's ability to adapt laser processes to the most specific industrial constraints. Beyond simply depositing material, the challenge lies in precisely controlling thermal, metallurgical and process phenomena.
The combination of technical expertise, in-house technological developments and advanced industrial equipment thus makes it possible to offer robust solutions for critical applications.
At a time when certain long-established skills are becoming increasingly rare, laser processes open up new prospects for safeguarding and industrialising surface treatments that are essential to the performance of industrial equipment.
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