Zhuojin Pipe Fitting Co., LtdFe-05 Wear-Resistant Alloy Powder Block Surfacing of Blower Impeller Blades
Literature Overview
This 1991 publication in Welding by Zhang Jiakun from the fly ash water division of Longkou Power Plant presents a practical engineering application of Fe-05 wear-resistant alloy powder block surfacing on blower impeller blades. The study addresses a specific industrial problem: the premature wear of blower impeller blades in a dry cyclone dust collector system at a 100 MW power generation unit. The work represents early Chinese industrial practice in wear-resistant surfacing technology, focusing on real-world problem solving in the power generation sector.
Core Technical Content
The Longkou Power Plant's first phase project employed two 100 MW units with dry cyclone dust collectors. Due to equipment aging and insufficient flushing water supply, the dust collection efficiency had dropped to only 70-80%, resulting in excessive fly ash entrainment in the blower system. This led to severe abrasive wear of the blower impeller blades, necessitating frequent maintenance and replacement.
The Fe-05 wear-resistant alloy powder block surfacing was applied to the impeller blades to extend their service life. The powder block surfacing method involves welding pre-formed alloy powder blocks onto the substrate surface, followed by mechanical machining to achieve the required blade geometry.
Application Context and Problem Analysis
| Parameter | Description |
|---|---|
| Facility | Longkou Power Plant, Phase 1 |
| Unit capacity | 2 × 100 MW |
| Dust collector type | Dry cyclone |
| Collection efficiency | 70-80% (degraded) |
| Root cause | Equipment aging + insufficient flushing water |
| Component affected | Blower impeller blades |
| Failure mode | Abrasive wear from fly ash particles |
| Solution | Fe-05 powder block surfacing |
Interpretation of Technical Points
The powder block surfacing method represents a practical approach to applying wear-resistant overlays on complex geometries such as impeller blades. Unlike wire surfacing or powder surfacing, which require precise gun manipulation on curved surfaces, powder blocks can be pre-formed and positioned, then welded in place using a consumable electrode. This method is particularly advantageous for:
- Complex three-dimensional geometries where wire feeding is difficult
- Thick overlay requirements where multi-pass wire surfacing would be impractical
- Field repair applications where portable equipment is preferred
- Maintaining precise blade geometry after surfacing, as the blocks can be machined to final dimensions
The Fe-05 alloy is a high-carbon, high-chromium cast iron-based alloy designed for severe abrasion resistance. The high carbon and chromium content promotes the formation of hard carbide phases (such as M₇C₃ and M₃C) that provide excellent resistance to sliding and abrasive wear. The powder block format allows for consistent composition and microstructure, unlike cast overlay blocks which may have segregation and porosity issues.
Engineering Practice Implications
This case study illustrates the practical problem-solving approach to wear-resistant surfacing in power generation facilities. The root cause analysis—identifying that the dust collector degradation (due to equipment aging and water supply issues) led to excessive fly ash in the blower system, which in turn caused impeller blade wear—demonstrates the importance of understanding the full degradation chain rather than treating symptoms.
For power plant maintenance engineers, this work highlights several important points:
- Powder block surfacing is a viable repair method for complex geometries that are difficult to access with conventional surfacing equipment
- The selection of Fe-05 alloy for fly ash abrasion is appropriate, as fly ash particles are hard (primarily silica and alumina) and require a correspondingly hard overlay material
- The machining step after surfacing is critical for maintaining blade aerodynamic performance, as surface roughness directly affects blower efficiency
- Regular inspection and timely resurfacing can prevent catastrophic blade failure that could damage the entire blower system
FMEA Perspective on Impeller Blade Wear
Applying a Failure Mode and Effects Analysis (FMEA) approach to this problem:
- Failure mode: Blade edge wear leading to imbalance and vibration
- Cause: Abrasive fly ash particles impinging on blade surfaces at high velocity
- Effect: Reduced blower efficiency, increased vibration, potential blade detachment
- Severity: High (can cause equipment shutdown and production loss)
- Detection: Regular vibration monitoring and visual inspection
- Prevention: Wear-resistant surfacing, dust collector efficiency restoration, regular maintenance
Key Questions and Reflections
This 1991 study reflects the state of industrial surfacing practice in China at that time. Modern powder block surfacing alloys have evolved significantly, with improved composition control, reduced porosity, and enhanced toughness. The Fe-05 alloy may still be in use, but newer alloy formulations with better hot hardness and thermal shock resistance may now be available for similar applications.
A key question is the long-term durability of powder block surfacing on impeller blades subjected to both abrasive wear and cyclic stress loading. The interface between the surfacing layer and the substrate is a potential crack initiation site, particularly under cyclic loading. Modern practice would require fracture mechanics evaluation of the interface to ensure adequate fatigue life.
The study also raises the broader question of whether surfacing the blades is the most cost-effective solution compared to restoring the dust collector system to proper efficiency. If the root cause (excessive fly ash) is addressed, the blade wear rate would decrease significantly, potentially extending blade life without surfacing. However, given the capital cost of dust collector replacement versus the relatively low cost of blade resurfacing, the surfacing approach may still be economically justified.
Study Insights and Implications
This practical case study provides valuable insight into the application of wear-resistant surfacing in power generation equipment maintenance. The powder block surfacing method demonstrated here remains relevant for field repair of complex geometries, and the systematic approach of identifying the root cause of wear before selecting a surfacing solution is a methodology that applies universally. For engineers working in power plant maintenance, this work serves as a reminder that surface engineering solutions must be integrated into a broader maintenance strategy that addresses root causes. The combination of material selection (Fe-05 for fly ash abrasion), process selection (powder block for complex geometry), and geometric finishing (machining for aerodynamic performance) represents a complete engineering approach to wear-resistant surfacing that can be adapted to similar applications in other industries. The enduring value of this work lies in its demonstration that practical, field-proven solutions to industrial wear problems can be developed through systematic analysis and appropriate technology selection.