CLADDING TECHNOLOGY SHANXI CO., LTDAlloy Cladding Application in Coke Quenching Blower at Jinan Iron and Steel
Literature Overview
Published in 2005 in the journal "Shandong Metallurgy" by Li Xuanliang and Han Fujian from the Coking Plant of Jinan Iron and Steel Group, this study documents the application of alloy overlay welding technology on the impeller blades and wear surfaces of a coke quenching blower. The coke quenching process generates high-velocity gas streams carrying abrasive coke dust particles, resulting in severe erosive wear of the blower components. The overlay solution extends the service life of these critical rotating components by orders of magnitude compared to the base material.
Wear Mechanism Analysis and Material Selection
The wear mechanism in coke quenching blowers is classified as abrasive erosion, where hard particulate matter in the gas stream impacts the blade surface at velocities exceeding 60 m/s. The selected overlay material is a high-chromium cast iron alloy (HCRI) with 25–30% Cr and 1.5–2.5% C, providing excellent resistance to dry sliding and abrasive wear through the formation of chromium carbide networks.
| Material Property | Base Steel (Q235) | Overlay Alloy (HCRI) |
|---|---|---|
| Hardness (HV) | 120–160 | 550–650 |
| Cr content (%) | 0.2–0.5 | 25–30 |
| C content (%) | 0.14–0.22 | 1.5–2.5 |
| Wear life (months) | 2–3 | 18–24 |
| Impact toughness (J) | 45–60 | 15–25 |
The trade-off between hardness and toughness is managed through a layered approach: a transition layer of austenitic stainless steel (309L) is deposited first to improve metallurgical compatibility with the base steel, followed by the high-chromium alloy overlay.
Welding Process and Fabrication Details
The overlay is applied using submerged arc welding (SAW) with a flux-cored wire for the transition layer and a covered electrode for the final overlay pass. The preheating temperature is maintained at 200–250 °C to prevent cracking in the high-carbon overlay. The welding sequence follows a zigzag pattern to ensure uniform coverage and minimize residual stress concentration. Post-overlay machining is required to restore the aerodynamic profile of the impeller blades, with a minimum remaining overlay thickness of 3 mm after machining.
Performance Verification and Field Results
Field testing demonstrated that the overlay-protected blower impellers achieved a service life of 18 to 24 months compared to the original 2 to 3 months for uncoated components. This represents a 6- to 8-fold improvement in service life, translating to significant cost savings in spare parts inventory and maintenance downtime. Metallographic examination of the worn surfaces revealed a dense chromium carbide structure with minimal spalling, confirming the effectiveness of the overlay material selection.
Study Insights and Engineering Recommendations
The success of this application underscores the importance of matching the overlay material to the specific wear mechanism rather than applying a generic corrosion-resistant alloy. Engineers designing overlay solutions for abrasive service should always conduct a wear mechanism analysis first, considering particle hardness, impact velocity, and impact angle. The layered approach with a transition layer is essential when the base and overlay materials have significant differences in carbon content and thermal expansion coefficient. Future improvements could include the use of plasma transferred arc (PTA) cladding for even finer microstructure and lower dilution, or laser cladding for selective repair of localized wear areas.