ENDURA CCO (Chromium Carbide Overlay)

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ENDURA CCO (Chromium Carbide Overlay) Abrasion Resistance

ENDURA CCO (chrome carbide overlay steel plate) is a type of composite wear plate designed for extreme abrasion resistance in high-wear environments. It consists of a base steel plate overlaid with a hard, abrasion resistant layer of chromium carbide. This overlay is typically applied through a welding process, such as submerged arc welding or open arc welding, where a mix of chromium and carbon is deposited onto the base steel.

Key Features

Abrasion Resistance: The chromium carbide layer provides exceptional hardness, often in the range of 55-62 HRC (Rockwell Hardness), making it resistant to wear from materials like coal, sand, gravel, and other abrasive substances.

Toughness and Strength: The base steel plate provides structural strength and toughness, allowing the CCO plate to be used in demanding applications without cracking or failure.

Heat Resistance: The chromium carbide overlay can withstand high temperatures, often up to 600°C (1112°F), making it suitable for use in high-temperature environments.

Cost-Effectiveness: By combining a wear-resistant surface with a durable steel backing, CCO plates extend the lifespan of equipment, reducing maintenance costs and downtime.

Customizable Thickness: The thickness of the base steel and the overlay layer can be adjusted based on specific application needs.

Advantages

Excellent resistance to wear and abrasion
Prolongs the service life of equipment
Reduces maintenance and replacement costs
Performs reliably in harsh conditions involving impact and temperature fluctuations

However, ENDURA CCO not ideal for applications where corrosion is a significant factor unless additional coatings or treatments are applied to protect the steel.

Common Applications of ENDURA CCO

Mining and quarrying equipment (chutes, hoppers, and crushers)
Cement industry (cyclones, fan blades, and ductwork)
Steel mills (coal pulverisers, liners, and wear plates)
Power plants (ash handling systems and ductwork)
Agriculture (harvesting and tilling equipment)

Mechanical Properties of ENDURA CCO

Hardness

Overlay Layer: Typically ranges from 55-62 HRC (Rockwell Hardness Cl) or around 600-700 BHN (Brinell Hardness Number). This high hardness is due to the formation of chromium carbide particles in the overlay.
Base Steel: The hardness of the base steel is lower, usually around 200-300 BHN, as it serves to provide structural support and flexibility.

Abrasion Resistance

Exceptional Wear: The chromium carbide content in ENDURA CCO provides exceptional resistance to wear from sliding, impact, and abrasive materials such as sand, coal, and ore. Its wear life can be 3-5 times longer than that of standard abrasion-resistant steel.

Impact Resistance

Base Steel: Offers toughness and impact resistance, typically being mild steel or a low-alloy steel with good ductility.
Overlay Layer: While extremely hard, it is brittle and can clack under severe impact. However, the ductile base steel absorbs the energy to prevent catastrophic failure.

Tensile Strength

The tensile strength is primarily determined by the base steel, often around 400-700 MPa depending on the grade of the steel plate.

Compressive Strength

ENDURA CCO has extremely high compressive strength due to the hardness of the chromium carbide particles, generally exceeding 1500 MPa. This makes it ideal for heavy-duty wear applications.

Heat Resistance

ENDURA CCO plates can typically withstand temperatures up to 600°C (1112°F).
Specialized formulations with additional alloys may offer resistance up to 800°C (1472°F).

Flexibility and Formability

The base steel provides some degree of flexibility, but bending or rolling must be done cautiously to avoid cracking the overlay. This property depends on the thickness of the overlay and base plate.

Bond Strength

The overlay is metallurgically bonded to the base steel, ensuring high adhesion strength. Typical bond strength exceeds the tensile strength of the base metal, meaning the overlay will not delaminate under normal use.

Summary of ENDURA CCO Mechanical Properties

Property	Overlay Layer	Base Steel
Hardness	55-62 HRC / 600-700 BHN	200-300 BHN
Tensile Strength	N/A (brittle)	400-700 MPa
Compressive Strength	> 1500 MPa	400-700 MPa
Abrasion Resistance	Extremely high	Moderate
Impact Resistance	Low	High
Heat Resistance	Up to 600°C (standard)	Varies
Bond Strength	Very high metallurgical bond	N/A

Chemical Composition of ENDURA CCO (Typical)

Chromium (Cr): 25-40%
Carbon (C): 3-5%
Iron (Fe): Balance

Other alloying elements (e.g. manganese, molybdenum, or vanadium) may be included to enhance specific properties.

ENDURA CCO Cutting

Cutting Speeds

1. Plasma Cutting (Recommended)

Plasma cutting is the most common and efficient method for cutting CCO plates because it handles the hardness of the chromium carbide overlay well.

Recommended Cutting Speed:

For a 10-12 mm (0.4-0.5 inch) thick plate: 0-1.5 m/min (40-60 inches/min).
For thicker plates (20+ mm): Reduce the speed proportionally to ensure a clean cut.

Key Considerations:

Use a high-definition plasma cutter with adequate amperage for the plate thickness.
Ensure consistent speed to avoid overheating, which may cause delamination or micro-cracking of the overlay.

2. Oxy-Fuel Cutting

Not recommended for CCO plates because the chromium carbide overlay has a high melting point and resists oxidation.

If necessary, preheating the base steel to 200-300″C (392-572″F) can improve results, but cutting will be slow and uneven.

3. Abrasive Waterjet Cutting

Highly effective for precise cuts without generating heat or thermal stress.

Recommended Cutting Speed:

Typically 5-1.0 m/min (20-40 inches/min), depending on the thickness of the plate and the abrasive used.

Advantages:

No heat-affected zone (HAZ).
Clean edges with minimal post-processing required.

Limitations:

Slower and more expensive than plasma cutting.

4. Mechanical Cutting (Grinding or Sawing)

Mechanical methods are less common but can be used for small cuts.

Recommended Cutting Speed:

Use a low cutting speed to prevent overheat and tool wear.
For example, a circular saw with carbide or diamond-tipped blades: 30-50 m/min (100-165 ft/min) surface speed.

Key Considerations:

Use tools with high wear resistance (carbide-tipped or diamond blades).
Coolant is essential to reduce heat and extend tool life.

5. Laser Cutting

Laser cutting is not typically recommended for CCO plates due to the high reflectivity and thermal conductivity of the overlay. If attempted, cutting speeds should be very slow, and high-power lasers are required.

Summary of Cutting Speeds

Cutting Method	Recommended Speed	Notes
Plasma Cutting	1.0-1.5 m/min (40-60 inches/min)	Best for general purpose cutting
Abrasive Waterjet Cutting	0.5-1.0 m/min (20-40 inches/min)	Cleanest and most precise method
Mechanical Cutting	30-50 m/min (100-165 ft/min)	Best for small sections; use coolant
Oxy-Fuel Cutting	Not recommended	Difficult due to high melting point
Laser Cutting	Not recommended	Requires very slow speeds and high power

Tips for Cutting CCO Plates

1. Pre-Cut Preparation:

Mark the cut line clearly and clamp the plate securely to avoid vibrations.
Choose the cutting method and speed based on the thickness and application requirements.

2. Heat Management:

Minimize heat input to avoid altering the properties of the overlay or base plate.
Use appropriate cooling methods (e.g., water or air jets).

3. Edge Cleanup:

After cutting, edges may need grinding to remove sharpness or slag for a smoother finish.

4. Safety Gear:

Cutting generates intense heat, sparks, and debris. Use appropriate personal protective equipment (PPE), including googles, gloves, and a face shield.

Welding and Bolting with ENDURA CCO

1. Welding ENDURA CCO to a Substrate

Welding ENDURA CCO plates involves joining the mild steel backing of ENDURA CCO plate to the substrate. The process requires specific techniques to avoid damaging the hard and brittle chromium carbide overlay.

Welding Process

Base Material Compatibility:

The base steel of ENDURA CCO plate is typically mild steel or a low-alloy steel, which can be welded using standard mild steel welding techniques.

Welding Methods:

Common methods include MIG (Metal Inert Gas) welding, stick welding (SMAW), or flux-cored arc welding (FCAW). TIG welding is less common due to its slower speed.

Steps:

Preparation: Clean the welding area on both ENDURA CCO plate and the substrate to remove contaminants such as rust, oil, or debris.
Positioning: Align ENDURA CCO plate on the substrate and secure it using clamps or tack welds.
Welding the Backing Plate: Weld only the mild steel backing of ENDURA CCO plate. Avoid applying heat directly to the chromium carbide overlay, as it can cause spalling or cracking.
Stress Relief Cracks: Allow for expansion cracks in the overlay. These cracks are normal and do not affect wear performance.

Welding Rods and Wires

Use a welding consumable compatible with mild steel, such as:

AWS E7018 for SMAW
ER70S-6 for MIG
Flux-cored wires (e.g., ETlT-1) for FCAW

Precautions

Avoid Excessive Heat: Too much heat can alter the properties of the base plate or cause delamination of the overlay.
Avoid Welding the Overlay: The overlay is brittle and prone to cracking when welded.

2. Bolting ENDURA CCO to a Substrate

Bolting is an alternative to welding, often used for applications requiring easy installation, removal, or replacement of the wear plate.

Bolting Process

1. Drilling Holes:

Holes are drilled through ENDURA CCO plate for bolting. Typically, these are pre-drilled at the manufacturing stage to avoid damage to the overlay.
If drilling is required on-site, use a carbide-tipped drill bit and drill at low speeds to avoid cracking the overlay.

2. Bolting:

High-strength bolts (e.g., Grade 8 or equivalent) are used to attach ENDURA CCO to the substrate.
Flat washers or spacer plates may be used to distribute load evenly and prevent bolt heads from damaging the overlay.

3. Gasket or Sealant (Optional):

In some applications, a gasket or sealant is placed between ENDURA CCO and substrate to reduce vibration or seal against fluid ingress.

Advantages of Bolting

Ease of Replacement: Plates can be removed and replaced without cutting or grinding.
Reduced Heat Concerns: Avoids risks associated with welding heat.
Flexibility: Allows for reconfiguration or adjustment of plates.

Precautions

Overlay Protection: Ensure bolt holes are positioned to avoid weakening the chromium carbide overlay.
Secure Fit: Bolts should be tightened sufficiently to prevent movement but not overtightened, which can crack the plate.

Choosing Between Welding and Bolting

Factor	Welding	Bolting
Strength	Permanent, strong bond	Removable, slightly less rigid
Ease of Installation	Requires skilled welders	Easier, especially for maintenance
Heat Concerns	Risk of damaging overlay	No heat involved
Maintenance	Harder to replace after wear	Easy to replace or reconfigure
Cost	Lower for large-scale installations	Higher initial cost due to fasteners

ENDURA CCO Microstructure

Hard Chrome Carbide Phase (Primary M7C3 Carbides)

Structure: The hard phase is usually composed of chromium carbides (M7C3), where M represents chromium and sometimes iron.
Characteristics:
- These carbides form elongated, or rod-like structures dispersed throughout the matrix.
- They are extremely hard (typically 1200-1800 HV), contributing to the plate’s high wear resistance.
- The volume fraction of carbides in the overlay can be 30-50% or more, depending on the specific application.

Metallic Matrix

Composition: The matrix is typically composed of austenitic or martensitic steel, which provides ductility and toughness.
Function:
- The matrix acts as a support structure for the hard carbides.
- It absorbs impact energy and prevents brittle fracture.

Microstructure Details

Heterogeneous Structure: The microstructure exhibits a eutectic network of chromium carbides in a softer steel matrix.
Directionality: During welding deposition, the carbides often align in a columnar structure perpendicular to the substrate due to directional solidification.
Dilution Zone: At the interface with the base metal, a dilution zone exists where elements from the base metal mix with the overlay material, leading to gradual property changes.

Base Metal (Backing Plate)

The base is typically mild steel or low-carbon steel, providing structural integrity and enabling easy welding or bolting to equipment.

Advantages of this Microstructure

Hard chromium carbides provide exceptional resistance to abrasive wear.
The metallic matrix enhances toughness, reducing the risk of cracking and spalling.
This synthetic combination delivers an optimal balance of wear resistance and structural support.