CLADDING TECHNOLOGY SHANXI CO., LTDDevelopment and Prospects of Cladding Technology in China
Literature Overview
The paper authored by Ren Yanyan, Zhang Guoshang, Wei Shizhong, and Xu Liujie, published in 2012 by researchers at Henan University of Science and Technology and the Henan Provincial Engineering Technology Research Center for Wear-Resistant Materials, provides a comprehensive review of the development trajectory of cladding technology in China. This work is significant because it documents the evolution of domestic cladding capabilities from simple oxy-acetylene overlay to advanced arc welding, plasma cladding, and laser cladding processes, reflecting the broader maturation of China's surface engineering industry.
Core Technical Content
The paper traces the historical progression of cladding technology in China through several distinct phases. Early domestic cladding relied heavily on oxy-fuel and submerged arc welding processes, which produced thick deposits (typically 3–6 mm per pass) with coarse microstructures and limited dilution control. The transition to gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) overlay represented a qualitative improvement, enabling thinner, more controlled deposits with better metallurgical bonding to the substrate. The paper also discusses the introduction of plasma transferred arc (PTA) powder cladding and laser cladding as high-energy-density alternatives that offer superior dilution control, typically achieving dilution rates below 10% compared to 20–40% for conventional arc processes.
| Process Category | Typical Dilution Rate | Deposit Thickness per Pass | Key Advantage |
|---|---|---|---|
| Oxy-acetylene | 30–50% | 1.5–3 mm | Low equipment cost |
| Submerged Arc Welding (SAW) | 20–35% | 3–6 mm | High deposition rate |
| GMAW / FCAW | 15–30% | 1–3 mm | Good flexibility |
| GTAW / TIG | 10–20% | 0.5–2 mm | Precise control |
| PTA Powder Cladding | 5–15% | 1–3 mm | Low dilution, uniform |
| Laser Cladding | 3–10% | 0.3–2 mm | Minimal dilution, fine microstructure |
Key Technical Points and Standards Context
A central theme of the paper is the standardization gap that China faced during the period of rapid cladding technology adoption. The authors highlight that while domestic manufacturers could produce functional cladding deposits, the absence of a unified national standard for cladding qualification testing created inconsistencies in quality assurance. The paper references the emerging framework of NB/T 47014 for weld procedure qualification and its applicability to overlay welding, as well as the role of ASTM A263 and A264 in specifying clad plate quality for pressure vessel applications. The authors advocate for the development of China-specific qualification procedures that account for the unique material combinations prevalent in domestic industries, such as austenitic stainless steel overlay on Q345R low-alloy steel substrates for hydrogenation reactor construction.
The paper also addresses the metallurgical challenges inherent in cladding, particularly the formation of martensitic transformation zones at the cladding-substrate interface. When overlaying austenitic stainless steel deposits on carbon or low-alloy steel substrates, the dilution of carbon and alloying elements into the first pass can produce a hard, brittle martensitic band that is susceptible to cracking under thermal cycling. The authors recommend preheating substrates to 150–250°C, controlling interpass temperatures below 150°C, and using high-dilution-resistant filler metals such as ER309L or ER310L for the first pass, transitioning to ER308L or ER316L for subsequent passes to achieve a graded dilution profile.
Integration with Engineering Practice
From a pressure vessel fabrication perspective, the paper's discussion of cladding process selection is directly relevant to the design and fabrication of hydrogenation reactors, ammonia synthesis converters, and acid-resistant storage tanks. The authors note that the Chinese petrochemical industry in the early 2010s was transitioning from imported clad plate (such as EN 10028-7 compliant products) to domestically manufactured alternatives, and that the quality of domestic weld-overlay cladding was a critical bottleneck. The paper advocates for the adoption of multi-pass cladding procedures with progressive dilution control, post-weld heat treatment (PWHT) at 650–720°C for austenitic overlay deposits, and comprehensive non-destructive testing including magnetic particle inspection (MT) of the cladding surface and ultrasonic testing (UT) for bond integrity.
Study Insights and Reflections
This paper serves as a valuable historical document capturing the state of cladding technology in China at a pivotal moment. Its emphasis on standardization and qualification reflects the practical reality that technological capability alone is insufficient without a robust quality infrastructure. For current practitioners, the paper's recommendations regarding dilution control, interpass temperature management, and PWHT remain fundamental principles that govern cladding procedure development. The advocacy for domestic standard development foreshadowed the subsequent issuance of updated versions of NB/T 47014 and related standards that now provide a more comprehensive framework for overlay welding qualification in pressure vessel applications.