Application of Wear-Resistant Cladding Materials in China Cement Industry

Overview and Industry Context

The cement industry in China has undergone rapid expansion over the past two decades, with annual production exceeding 2 billion tonnes. This massive output has brought severe challenges related to material wear in critical components such as kiln liners, preheater cyclones, fan blades, grinding mill rollers, and conveyor chutes. The present study review focuses on the application of wear-resistant cladding materials specifically tailored to the harsh operating environments encountered in cement production lines. The literature surveys the types of cladding materials deployed, their fabrication methods, field performance data, and the economic rationale behind adopting weld overlay solutions over conventional material replacement strategies.

Key Cladding Materials and Their Applications

The review identifies several categories of wear-resistant overlay materials used in cement plants:

Cladding Material System	Typical Hardness (HV)	Application Location	Expected Service Life Improvement
High-carbon martensitic steel (C 1.5–2.5%)	500–600	Fan blades, ducting	3–5×
Cr-Cr2C3 hardfacing (Cr 20–30%)	450–550	Kiln transition pieces	4–6×
Fe-Cr-C-B alloy	600–800	Mill liners, chutes	5–8×
Ni-Cr-Cr3C2 composite	400–500	Hot gas ducts	3–4×
Tungsten carbide composite (WC-Co)	1200–1600	Roller necks, wear rings	8–12×

The cement kiln system presents a unique combination of thermal cycling, abrasive particle impact, and mild chemical attack. The literature emphasizes that material selection must balance hardness against toughness, as excessively brittle overlays crack under thermal shock in the preheater and cooler zones.

Fabrication Methods Discussed

The study highlights the following fabrication techniques employed in cement plant maintenance:

Submerged Arc Welding (SAW) overlay: Preferred for thick overlay layers (3–10 mm) on kiln liners and large duct sections. Multiple passes are applied with alternating base and overlay consumables to control dilution.
Flame spraying and oxy-fuel welding: Used for repair of smaller components and field repairs where equipment portability is critical.
Plasma Transferred Arc (PTA) cladding: Applied to high-value components such as grinding mill rollers where dimensional accuracy and low dilution are required.
Electroslag Welding (ESW) overlay: Occasionally used for clad plate fabrication of pressure vessels and large storage tanks in cement chemical plants.

Engineering Insights and Reflections

From a practical standpoint, the most significant finding is the strong correlation between overlay layer hardness and actual service life in abrasive environments, but with an important caveat: hardness above 700 HV often leads to premature cracking in thermally cycled components. The optimal hardness window for cement industry applications appears to be 550–700 HV, where sufficient abrasive resistance coexists with adequate thermal fatigue resistance.

The literature also notes that proper preheating and interpass temperature control are frequently neglected in field repairs, leading to hydrogen-induced cracking in high-carbon martensitic overlays. A minimum preheat of 150–200°C is recommended for carbon equivalents exceeding 0.5%, with post-weld stress relief at 550–600°C for critical components.

Defect Analysis and Countermeasures

Common defects observed in cement plant cladding repairs include:

Defect Type	Root Cause	Countermeasure
Cracking in overlay layer	High carbon equivalent, rapid cooling	Preheat, controlled cooling, post-weld heat treatment
Excessive dilution (>30%)	Insufficient overlay passes, poor consumable selection	Increase pass count, use alloyed flux
Porosity	Flux contamination, inadequate shielding	Flux drying, proper gas coverage
Delamination at interface	Poor base metal preparation, inadequate penetration	Mechanical cleaning, increased heat input

Study Conclusions

The comprehensive application of wear-resistant cladding in China's cement industry demonstrates that proper material selection, process parameter optimization, and quality control can extend component service life by 3 to 12 times compared to uncladded alternatives. The economic justification is clear when considering the high cost of kiln shutdowns and component replacement. Engineers should prioritize a systematic approach to cladding specification, incorporating service condition analysis, material compatibility assessment, and rigorous non-destructive testing protocols to ensure long-term reliability of wear-critical components.