Chromium Carbide Overlay Welding

Chromium carbide overlay welding is a hardfacing process used to create extremely wear-resistant steel plates and components. By welding a chromium-rich alloy layer onto a steel base plate, a surface with high hardness, abrasion resistance, and long service life is formed.
This technology is widely used in mining, cement, power plants, steel mills, and bulk material handling systems.

Structure of Chromium Carbide Overlay Plate

A chromium carbide overlay plate is a composite welding steel made of two layers:

The overlay contains chromium carbides (Cr₇C₃ and Cr₂₃C₆), which are responsible for its exceptional hardness.

Chromium Carbide Overlay Welding Process

1. Base Plate Preparation

The carbon steel base plate is cleaned to remove:

• Rust

• Oil

• Scale

This ensures strong metallurgical bonding during welding.

2. Hardfacing Alloy Welding

A special chromium carbide welding wire or flux-cored wire is used.
The overlay is deposited by automated welding processes such as:

• Flux-Cored Arc Welding (FCAW)

• Submerged Arc Welding (SAW)

• Open Arc Welding (OAW)

These processes allow precise control of alloy composition and layer thickness.

3. Formation of Carbide Microstructure

During welding:

• Molten alloy solidifies on the base steel

• Chromium carbides crystallize inside the overlay layer

• These hard carbides are embedded in a tough alloy matrix

This creates a surface hardness of HRC 55–65.

4. Stress Relief Crack Pattern

After cooling, a network of fine, evenly spaced cracks appears in the overlay.
These cracks:

• Release thermal stress

• Prevent large structural cracking

• Do not affect wear resistance

This is a designed feature, not a defect.

5. Cutting and Forming

The finished overlay plate is cut using:

• Plasma cutting

• Laser cutting

• Water-jet cutting

It can then be formed into:

• Wear liners

• Chute plates

• Bending segments

• Pipes and conveyor components

Why Chromium Carbide Overlay Welding Is Used

This welding process provides:

• Extremely high abrasion resistance

• Strong metallurgical bonding

• Customizable overlay thickness

• Lower cost than solid wear-resistant alloy steel

• Easy repair by re-welding

Typical Applications

Chromium carbide overlay plates are used in:

• Mining and quarrying equipment

• Cement plant chutes and hoppers

• Coal handling systems

• Power plant ash conveyors

• Steel mill material handling

These environments involve severe sliding abrasion, impact, and particle erosion.