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

Literature Overview and Historical Perspective

This comprehensive review by Shan Jiguo, Dong Zuyue, and Xu Binshi (Welding Society of China, Cladding and Surface Engineering Committee, 2002) provides a historical overview and technical assessment of cladding technology development in China and its application across basic industries including energy, petrochemical, mining, and construction. The paper serves as a valuable reference document for understanding the evolution of cladding technology from its introduction in China during the 1950s through the early 2000s, covering both traditional welding overlay methods and advanced thermal spray and surfacing technologies.

Evolution of Cladding Technology in China

The development of cladding technology in China can be divided into several phases:

Phase 1: Introduction and Early Adoption (1950s–1960s)

During this period, basic welding overlay techniques were introduced from the Soviet Union and Western Europe. Submerged arc welding (SAW) overlay was the primary method, used for cladding carbon steel vessels with stainless steel liners in petrochemical and power generation applications. The early work focused on establishing basic welding procedures, qualifying filler metals, and developing inspection methods. Key achievements included:

Development of domestic stainless steel welding electrodes (E308, E309, E316 equivalents)
Establishment of welding procedure qualification requirements for overlay welding
Introduction of basic non-destructive testing methods (RT, MT, PT)

Phase 2: Expansion and Diversification (1970s–1980s)

This period saw significant expansion of cladding technology capabilities:

Introduction of electroslag welding (ESW) for thick-section cladding
Development of multi-layer multi-pass overlay techniques for thick cladding layers
Adoption of gas tungsten arc welding (GTAW) for precision overlay of thin sections
Introduction of flame spraying and plasma spraying for surface hardening
Application of explosive cladding for bimetallic plate production

Phase 3: Advanced Technologies and Industrial Applications (1990s–2000s)

The 1990s and early 2000s marked the era of advanced cladding technologies:

Plasma transferred arc (PTA) cladding became commercially available and widely adopted
Laser cladding was introduced for precision repair and surface engineering
Hot-wire TIG cladding was developed for high-deposition-rate applications
Multi-alloy cladding systems were developed for complex service environments
Integration of cladding with additive manufacturing concepts began to emerge

Application in Basic Industries

Energy Sector

In the power generation industry, cladding technology is applied extensively for:

Boiler tubes: Overlay cladding of superheater and reheater tubes with Ni-based alloys to resist high-temperature oxidation and hot corrosion. Typical applications include cladding of 12Cr1MoV and 9Cr1Mo tubes with Inconel 625 or Haynes 230 in ultra-supercritical (USC) boilers operating at 600–620°C.
Pressure vessels: Weld overlay cladding of carbon steel pressure vessel shells with 304L or 316L stainless steel for corrosion resistance in acid service or hydrogen-containing environments.
Turbine components: PTA cladding of turbine blade platforms and shrouds with CoCr alloys for hot corrosion resistance.

Petrochemical Industry

Cladding technology in petrochemical applications includes:

Heat exchangers: Cladding of carbon steel tubesheets with Hastelloy C276 or Inconel 625 for chloride stress corrosion resistance.
Reactors: Weld overlay of hydrogenation reactor linings with 316L or 904L stainless steel to resist hydrogen attack and corrosion.
Storage tanks: Internal cladding of atmospheric storage tanks with duplex stainless steel (2205) for resistance to sulfuric acid and chloride-containing environments.

Mining and Mineral Processing

Grinding media: Hardfacing of ball mill liners and grinding balls with high-chromium alloys or carbide-containing compositions.
Excavator buckets: Overlay cladding with wear-resistant alloys for improved service life in abrasive soil conditions.
Conveyor components: Cladding of conveyor rollers and chutes with abrasion-resistant alloys.

Construction and Infrastructure

Bridge components: Hardfacing of bridge bearings and expansion joints with wear-resistant alloys.
Railway components: Cladding of rail joints and switch components with high-hardness alloys.
Cement equipment: Cladding of grinding rollers and mill liners with C-Cr-Si-Mn alloys or high-chromium white iron.

Technology Comparison and Selection Guidelines

Technology	Deposition Rate	Layer Thickness	Cost	Surface Quality	Application
SAW overlay	5–15 kg/h	3–10 mm/pass	Low	Moderate	Thick cladding layers
ESW overlay	10–20 kg/h	5–15 mm/pass	Low	Good	Very thick cladding
GTAW overlay	0.5–2 kg/h	0.5–2 mm/pass	Moderate	Excellent	Thin, precise layers
GMAW overlay	3–8 kg/h	2–5 mm/pass	Low	Good	General purpose
PTA cladding	2–6 kg/h	1–3 mm/pass	High	Excellent	Precision, multi-alloy
Laser cladding	1–4 kg/h	0.5–2 mm/pass	High	Excellent	Repair, thin layers
Explosive cladding	N/A (bonding)	1–10 mm	High	Excellent	Bimetallic plate
Flame spraying	1–5 kg/h	0.1–1 mm/pass	Low	Moderate	Surface hardening
Plasma spraying	2–10 kg/h	0.1–0.5 mm/pass	Moderate	Good	Thermal barrier, wear

Standards and Quality Assurance

The development of cladding technology in China has been supported by the establishment of relevant standards:

GB/T 150: Pressure vessel design and fabrication, including requirements for clad vessels
NB/T 47002: Technical conditions for steel materials for pressure vessels
NB/T 47014: Welding procedure qualification for pressure vessels
JB/T 4730: Non-destructive testing of pressure vessels
GB/T 985: General technical requirements for welding
DL/T 869: Power industry welding procedures

Quality assurance for cladding operations typically follows a PDCA (Plan-Do-Check-Act) cycle:

Plan: Develop welding procedure specifications (WPS), qualify procedures per relevant standards, select appropriate filler metals, define inspection requirements.
Do: Execute cladding operations according to qualified procedures, maintain records of all process parameters, perform in-process inspections.
Check: Perform non-destructive testing (RT, MT, PT, UT), conduct mechanical property testing (hardness, tensile, impact), verify metallurgical quality (metallographic examination).
Act: Evaluate results against acceptance criteria, implement corrective actions for non-conformances, update procedures based on lessons learned.

FMEA Analysis of Common Cladding Defects

Defect	Cause	Detection Method	Prevention
Cracking	Excessive carbon, sulfur, thermal stress	MT, PT, RT	Control composition, preheat, PWHT
Lack of bond	Contamination, insufficient heat	UT, shear test	Surface preparation, adequate heat input
Porosity	Hydrogen, moisture, porosity in base	RT, UT	Drying, shielding gas purity
Dilution	Excessive heat input, thin layers	Metallography	Optimize parameters, bond layer
Inclusion	Slag entrapment, oxide inclusions	MT, PT	Interpass cleaning, flux quality

Study Insights and Strategic Implications

The review by Shan Jiguo and colleagues provides a valuable historical perspective on the development of cladding technology in China. Several key insights emerge from this analysis:

First, the development of cladding technology has always been driven by industrial demand. The energy sector's need for corrosion-resistant and wear-resistant components has been the primary driver of innovation in welding overlay and thermal spray technologies. This demand-driven approach ensures that technological development remains relevant to practical engineering needs.

Second, the integration of multiple cladding technologies is essential for meeting the diverse requirements of modern industrial applications. No single technology can address all cladding challenges; rather, a portfolio approach combining SAW for thick layers, PTA for precision applications, laser cladding for repair, and explosive cladding for bimetallic plate production provides comprehensive coverage.

Third, the importance of standards and qualification cannot be overstated. The establishment of robust standards frameworks (GB, NB, JB, DL/T) has been instrumental in ensuring consistent quality and facilitating technology transfer across industries. Engineers must remain current with evolving standards and ensure that their practices comply with the latest requirements.

Fourth, the trend toward advanced materials and technologies continues to drive innovation. The development of nickel-based superalloys, high-entropy alloys, and functionally graded materials for cladding applications represents the next frontier in cladding technology. Engineers should stay informed about these developments and be prepared to adopt new materials and technologies as they become commercially viable.

This comprehensive review serves as an essential reference for engineers entering the field of cladding technology, providing both historical context and practical guidance for technology selection and application in basic industries. The lessons learned from decades of development in China offer valuable insights for engineers worldwide, particularly regarding the importance of integrating metallurgical understanding, process engineering, and quality assurance to achieve reliable and cost-effective cladding solutions.