The role of boron carbide (B₄C) in welding rods

The role of boron carbide (B₄C) in welding rods

Enhanced wear resistance
Boron carbide is one of the hardest known ceramic materials. Its high hardness and wear resistance make it a key component of wear-resistant cladding welding rods. During the cladding process, boron carbide particles are embedded in the weld metal matrix as a hard phase to form a composite material structure, which significantly improves the wear resistance of the surface and is suitable for the repair of easily worn parts such as mining machinery and crusher rollers.

High temperature stability and arc protection
The melting point of boron carbide is as high as 2450℃, and it can remain stable at high welding temperatures. Adding boron carbide to the coating can enhance the high temperature resistance of the coating, reduce premature decomposition of the coating, ensure arc stability and continuous release of protective gas (such as CO₂), effectively isolate the air, and prevent oxidation of the molten pool.

Alloying and grain refinement
Under the action of high temperature arc, boron carbide may partially decompose and release boron (B) and carbon (C). Boron can penetrate into the molten pool and play a role in refining the grains, thereby improving the strength and toughness of the weld. At the same time, the addition of carbon can adjust the carbon content of the weld metal, optimize the hardness and wear resistance, but the amount needs to be controlled to avoid increased brittleness.

Auxiliary deoxidation and purification effect
Boron has a strong affinity for oxygen and can combine with oxygen in the molten pool to form boron oxides (such as B₂O₃), reduce oxide inclusions, and improve the purity of the weld. Although this deoxidation effect is not as significant as traditional deoxidizers (such as silicon and manganese), it can be used as a supplementary purification mechanism.

Special application scenarios
In the nuclear industry or neutron shielding field, boron carbide may be used in special welding rods due to its excellent neutron absorption ability to enhance the neutron shielding performance of the weld, although this application is relatively niche.

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