Development of Cladding Technology in China and Its Application in Basic Industries

Literature Overview

This 2002 publication in China Surface Engineering (Zhong Guo Biao Mian Gong Cheng) by Shan Jiguo, Dong Zuyue, and Xu Binshi from the Cladding and Surface Engineering Committee of the Chinese Welding Society provides a comprehensive review of the development of weld overlay (cladding) technology in China and its applications across fundamental industries. Published at a time when China was rapidly industrializing and expanding its heavy equipment manufacturing capacity, this review serves as both a historical document and a technical roadmap for the future development of cladding technology in the country. The authors, all recognized experts in the field, bring extensive practical and academic experience to this survey.

Historical Development and Technology Evolution

The review traces the evolution of cladding technology in China from its early adoption in the 1950s and 1960s to the advanced state achieved by the early 2000s. The development can be divided into several phases:

Early stage (1950s–1970s): Primarily oxy-acetylene flame welding and manual metal arc welding (SMAW) for surface hardening and repair of mining equipment, cement mill liners, and excavator buckets.
Growth stage (1980s–1990s): Introduction of submerged arc welding (SAW) for heavy overlay applications, plasma transferred arc (PTA) cladding for high-performance overlays, and laser cladding for precision applications.
Advanced stage (2000s onward): Integration of numerical simulation, advanced powder metallurgy, and automated multi-axis cladding systems for complex geometries.

Technology Comparison Across Industries

Industry	Primary Cladding Process	Overlay Material	Application
Mining	SAW, SMAW	High-Cr martensitic (25–30% Cr)	Excavator buckets, crusher jaws
Cement	SAW, PTA	C-Cr-Si-Mn hardfacing	Grinding rollers, mill liners
Power generation	PTA, SAW	Ni-based (Stellite), Co-based	Steam turbine blades, boiler tubes
Petrochemical	SAW, ESW	Austenitic SS (309L, 310L)	Heat exchanger tubes, reactor internals
Shipbuilding	PTA, GMAW	Cu-Ni alloys, Ni-based	Propeller surfaces, hull components
Steel	PTA, Laser	Cr-based, Ni-based	Rolling mill rolls, continuous casting molds

Application Status in Key Industrial Sectors

The review provides detailed accounts of cladding technology applications across China's basic industries:

Mining and Earthmoving Equipment

Weld overlay cladding is the dominant technology for extending the life of earthmoving equipment components. Excavator buckets, dozer blades, and crusher jaws are typically clad with high-chromium martensitic hardfacing alloys (25–30% Cr, 2–3% C) using submerged arc welding or manual arc welding. The typical cladding thickness ranges from 3–10 mm, with multi-pass deposition to achieve the required thickness. The wear life extension achieved through proper cladding can be 3–10 times that of the unclad base material.

Power Generation

In coal-fired power plants, cladding technology is applied to boiler tube surfaces exposed to high-temperature ash deposition and corrosion, steam turbine blade surfaces subject to high-temperature oxidation, and pump impellers exposed to erosive and corrosive fluids. Plasma transferred arc cladding with nickel-based alloys (Stellite 6, 21) and cobalt-based alloys is the preferred method for high-temperature applications due to the superior oxidation resistance and hot hardness of these materials.

Petrochemical and Oil Processing

Cladding is extensively used in the petrochemical industry for heat exchanger tubes, reactor internals, and piping systems exposed to corrosive and erosive process fluids. Submerged arc welding and electroslag welding are commonly used for thick overlay deposits on large components, while PTA cladding is used for precision overlays on smaller components. The overlay materials typically include austenitic stainless steels (309L, 310L), nickel-based alloys (Inconel 625, Monel 400), and duplex stainless steels.

Key Challenges and Development Directions

The review identifies several critical challenges facing the further development of cladding technology in China:

Material development: The need for new overlay alloys tailored to specific service environments, particularly for ultra-high-temperature and multi-corrosion environments.
Process automation: The transition from manual and semi-automated cladding to fully automated and robotic cladding systems for improved quality consistency and productivity.
Quality assurance: The development of standardized inspection and testing procedures for cladding quality, including bond strength testing, overlay thickness measurement, and microstructural characterization.
Design methodology: The establishment of design codes and standards for cladded components, including stress analysis methods that account for the thermal mismatch between overlay and substrate.
Training and expertise: The need for skilled welders and engineers trained in cladding-specific techniques and metallurgy.

Study Insights and Strategic Implications

This review provides an invaluable overview of the state of cladding technology in China at the beginning of the 21st century. From a strategic perspective, the development of cladding technology is closely tied to China's broader industrial modernization agenda. The ability to manufacture high-performance cladded components domestically reduces dependence on imported equipment and extends the service life of critical industrial assets. The review also highlights the importance of standardization and quality control in ensuring the reliable performance of cladded components, which is particularly critical for safety-critical applications such as pressure vessels, nuclear components, and aerospace parts. The document serves as a valuable reference for understanding the historical context and future directions of cladding technology development in China, and its insights remain relevant for contemporary practitioners in the field.