What Is Laser Hardening?

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What Is Laser Hardening?

Laser hardening, often known as laser case hardening, is a heat treatment technique used to increase the strength and endurance of component surfaces. It makes use of high-powered diode lasers to heat targeted regions of the component’s surface. 

As the laser moves across the surface, it instantly heats the surface and a desired case above the austenizing temperature. As the laser passes over this volume of metal, it self-quenches (i.e., cools) rapidly through conduction, resulting in the formation of a martensitic structure and, as a result, the material hardening.

 

What Is Laser Hardening Process?

What Is Laser Hardening Process?

While laser hardening techniques vary significantly based on the item and manufacturing standards, they all follow the same fundamental stages.

  1. Placing the workpiece beneath the diode laser.The laser hardening method is appropriate for almost any carbon-containing steel or cast iron. The workpiece might be simple or complicated.
  2. Activating the laser.Once the workpiece is in the proper position, a preprogrammed robot program starts the laser, which warms the surface of the localized region to just below its melting point (usually between 900 and 1400° C). The lattice of carbon atoms rearranges itself in reaction to heat. This is known as austenitization.
  3. Moving the laser across the surface of the component.When the region beneath the laser beam achieves the desired temperature, the laser beam is set to travel over the workpiece’s surface following a preprogrammed route. The hardened case depth is determined by the laser energy per unit area, which is dictated by the laser power and surface speed. When the laser passes over an area, it rapidly conductively quenches it. The quick quench prevents the carbon atoms from reverting to their initial lattice formation and forming martensite, a harder crystalline structure. This structure is what toughened the case.

 

Important Considerations For Laser Hardening Are:

  • Substrate Substance: This process can only harden materials that have undergone transformation hardening; carbon steels, high carbon stainless steels, cast irons, and aluminum bronzes are commonly regarded hardenable.
  • Surface Treatment: The absorption of laser light into the substrate must be precisely managed; surface roughness and polish may substantially impact the quantity of laser energy reflected; hence, very reflecting surfaces are exceedingly difficult to laser harden.
  • Hardness Range: Laser hardening may create a hardened layer up to 1.5 mm thick into the base material. Deeper hardening often leads in lesser hardnesses.
  • Impact and tenacity: Laser hardening is capable of creating extremely hard microstructures, sometimes exceeding 1000 Hv; however, this comes at the expense of ductility; if your application requires high levels of toughness, laser cladding may be a better solution.

Advantages Of The Laser Hardening Process

When compared to alternative hardening techniques, laser hardening has various advantages, including:

  • Lower chance of distortion: In typical hardening processes, the combination of heating the entire workpiece or a larger part of the workpiece and subsequent liquid quenching operations leads in a significant risk of deformation and cracking in the treated workpieces. Laser hardening uses precise energy input and removes the need for liquid quenching. As a result, there is far less distortion.
  • Improved compatibility with tiny components: Diode lasers allow for fine control of surface temperature and laser beam placement. This capability enables the process engineer to predictably regulate the heat input, which is crucial for repeatable production hardening procedures.
  • Increased precision: In laser hardening processes, laser technology allows operators to precisely regulate the temperature and movement of the beam. This capacity allows them to precisely regulate the heat input, which is essential for consistent production hardening procedures.
  • Reduced processing costs: In comparison to other case hardening procedures like as flame and induction hardening, laser hardening is a non-contact process capable of producing only the appropriate case depth. This, along with the absence of the necessity for liquid quenching, results in smaller distortions, which eliminates the need for costly post-hard milling and grinding.
  • Greater part geometries suitability: Flame hardening and induction hardening, for example, have trouble treating workpieces with complicated geometries. Regardless of shape, the noncontact laser hardening technology may selectively case harden workpiece surfaces.
Advantages Of The Laser Hardening Process

Applications Of The Laser Hardening Process

Laser hardening is extremely adaptable, with fewer distortion risks, higher processing rates, and lower processing costs for a wide range of metal components. These characteristics make it suited for the treatment of a wide range of industrial and commercial components, including those used in the following industries:

Because laser hardening primarily affects the top layers of a workpiece, it is classified as a surface hardening treatment. It is used to increase the surface durability of a wide range of metal components, particularly those subjected to cyclical, mechanical, and wear forces (for example, mining bits and pistons). Tools and tooling, gearwheels, sprocket wheels, and camshafts are other common laser hardened items.

 

Where are diode lasers used for hardening?

This treatment is notably effective on wear-stressed or cyclically strained components like camshafts. Steel rubs against steel in every gasoline and diesel engine. As a result, the contact zones must be toughened; otherwise, the components would be short-lived. When it comes to these sophisticated systems, the inductive technique is useless. 

Modern camshaft construction (with varied shaped cams and shifting gates for cylinder deactivation or engine control changes) need accurate surface hardening, which is only attainable using diode lasers. Diode lasers have even been used for a long time in the production of big sheet metal tools, with the oldest hardening systems in service for 10 to 15 years.

What are the advantages of surface hardening?

Surface hardening may also increase steel’s strength and hardness. This means that surface-hardened steel is more resistant to deformation and breaking. Furthermore, surface-hardened steel frequently has a higher yield strength, at which point the material irreversibly deforms.

What are the benefits of laser hardening?

  •  Less reworking
  •  Hardening small and delicate components
  •  No distortion
  •  Precise control
  • Fast throughput time and high productivity
  • Completely independent of the geometry

laser hardening Machine

What is the difference between induction hardening and laser hardening?

Laser hardening creates less heat than induction hardening since it uses surface hardening technology via laser irradiation. Another advantage of laser hardening is its capacity to harden discrete regions that induction hardening cannot.

What is the hardness of laser hardening?

The laser-induced hardness is greater than the typical furnace hardness and falls inside the so-called superhardness band (41). In theory, any steel or iron that can be hardened conventionally may likewise be laser hardened.

What is the working principle of laser beam hardening process?

Laser hardening involves heating the skin of a carbon-containing workpiece composed of steel or cast iron to just below the melting point, which is typically between 900 and 1400°C. Around 40% of the electricity irradiated is absorbed.

What are the two methods of hardening?

Heat treatment and surface hardening are the two basic ways for accomplishing this, both of which require heating and cooling cycles to change the physical characteristics without affecting the shape or form. One approach may be preferred to another depending on your demands; nonetheless, both provide considerable benefits when it comes to reinforcing your metal components for industrial applications or other uses.

What types of surface-hardening?

There are various types of surface hardening processes, and they are as follows:

  • Carburizing: Carburizing is the process of diffusing carbon into the surface of a metal. This procedure is carried out in a furnace at high temperatures in the presence of carbon-rich gases or liquids. The metal is quenched in oil or water after carburizing to harden the surface.
  • Nitriding: Nitriding is the process of diffusing nitrogen into the surface of a metal. This procedure is carried out in a furnace at high temperatures in the presence of nitrogen-rich gases or liquids. The metal is quenched in oil or water after nitriding to harden the surface.
  • Cyaniding: Cyaniding is the diffusion of carbon and nitrogen into the surface of a metal. This procedure is carried out in a furnace at high temperatures in the presence of cyanide-based liquids. The metal is quenched in oil or water after cyaniding to harden the surface.
  • Carbonitriding: Carbonitriding is the diffusion of carbon and nitrogen into the surface of a metal. This process is carried out in a furnace at high temperatures in the presence of carbon- and nitrogen-rich gases or liquids. The metal is quenched in oil or water after carbonitriding to harden the surface.
  • Hardening by Induction: Induction hardening is a method that uses an electromagnetic field to heat the metal’s surface. This is accomplished by running an electric current via a coil, creating an electromagnetic field surrounding the metal. The heat created by this action diffuses into the metal’s surface and hardens it. The metal is quenched in oil or water after induction hardening to cool it down and complete the hardening process.
  • Surface-Hardened Metal Applications: Surface-hardened metals are utilized in a variety of applications such as gears, cams, crankshafts, connecting rods, and so on, where greater wear resistance and strength are required. Furthermore, these metals are employed in applications such as cutting tools, dies, injection molding dies, and so on.

What is a laser heat treatment?

Laser heat treatment, often known as laser hardening, is a surface modification procedure used to enhance wear resistance or extend the lifespan of objects ranging from household tools to automotive parts and heavy industry and transportation machinery.

Contact The Experts At Haitian For Your Laser Hardening Needs

The laser hardening technique is a quick and easy way to improve the surface durability of metal components. Because of its greater accuracy and lesser danger of distortion, it is perfect for hardening surfaces on very complicated, extremely tiny, or sensitive objects. Haitian’s laser hardening specialists are available to assist you if you’re seeking for an experienced and qualified laser hardening partner.

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