Wear-Resistant Overlay Cladding on Spiral Conveyor Auger Blades

Literature Overview

This 2018 paper by Ma Tiantian and Wang Bingjun from Tangshan Sanyou Chemical Engineering Design Co., Ltd. investigates the application of wear-resistant overlay cladding to spiral conveyor auger blades used in soda ash production. Published in "Soda Industry," this work addresses a specific and practical engineering challenge in the chemical processing industry where spiral conveyors transport abrasive materials such as soda ash, salt, and intermediate products.

Technical Background and Service Conditions

Spiral conveyor auger blades operate under severe abrasive and impact conditions in soda ash production facilities. The auger rotates within a trough, pushing material along its length. The blade surfaces are continuously subjected to:

• Abrasive wear from soda ash particles (SiO2, Na2CO3) with hardness up to 6-7 Mohs
• Impact loading from material clumps and bridging
• Corrosive attack from moisture and acidic components in the material
• Thermal cycling from hot process materials to ambient conditions

The base material for auger blades is typically low-carbon steel (Q235 or Q345) or low-alloy steel. Without protection, the service life of auger blades can be as short as 2-4 weeks under severe conditions, leading to frequent replacement and production disruption. Wear-resistant overlay cladding is a proven solution to extend service life by 3-10 times.

Overlay Material Selection and Process Design

The selection of overlay material depends on the specific service conditions:

For soda ash service, high-carbon martensitic alloys (Cr15-Cr20 type) are typically the most cost-effective choice, providing adequate hardness and wear resistance without the premium cost of cobalt-based alloys. The overlay thickness should be 3-5 mm to ensure adequate protection throughout the expected service life.

The welding process for auger blade overlay typically employs:

• SMAW with heavy-duty electrodes for small repairs and field applications
• SAW with submerged flux for workshop fabrication of new augers
• FCAW with flux-cored wire for medium-scale production
• GMAW with solid or flux-cored wire for automated production

The choice of process depends on production volume, available equipment, and required quality level. For a chemical plant with multiple augers requiring regular replacement, an automated SAW or FCAW process is preferred for consistency and productivity.

Process Parameters and Quality Control

The overlay welding process parameters for auger blades require careful optimization to achieve the desired hardness, bond strength, and dimensional accuracy:

Quality control for auger blade overlay should include:

• Visual inspection of all overlay surfaces for uniformity and absence of defects
• Hardness testing at multiple locations (minimum 3 per blade)
• Bond strength testing (peel test or bend test on test coupons)
• Dimensional inspection to ensure blade profile and auger pitch accuracy
• Surface roughness measurement to ensure acceptable finish for material flow

Defect Analysis and Countermeasures

Common defects in auger blade overlay and their countermeasures include:

The most critical defect is cracking, which can lead to overlay spalling and premature failure. The high-carbon martensitic overlay alloys are particularly susceptible to cold cracking due to their high hardenability and residual stress. The countermeasure is to use adequate preheat (150-250 °C), control interpass temperature, and consider a post-weld stress relief treatment at 550-650 °C.

Engineering Practice and Economic Analysis

For a soda ash plant with multiple spiral conveyors, the economic analysis of overlay cladding is straightforward. The cost of overlay welding (materials, labor, equipment) is significantly lower than the cost of frequent auger replacement. The extended service life reduces maintenance labor, production downtime, and spare parts inventory. A typical economic analysis shows:

• Cost of overlay welding per auger blade: 500-2000 CNY (depending on size and process)
• Cost of replacement blade: 1000-5000 CNY
• Extended service life: 3-10 times baseline
• Annual savings: 50-80% on auger-related maintenance costs

The practical implementation requires training of maintenance personnel in overlay welding techniques, establishment of quality control procedures, and development of standardized welding procedures (WPS) for each auger type and material combination.

Study Insights and Implications

This study provides practical guidance for chemical plant engineers addressing the wear problem of spiral conveyor auger blades in soda ash production. The key insight is that wear-resistant overlay cladding is a highly cost-effective solution that can dramatically extend auger blade service life while reducing maintenance costs and production disruption. The choice of overlay material, welding process, and process parameters should be tailored to the specific service conditions, including material abrasiveness, temperature, and corrosivity.

The practical orientation of this work—originating from a chemical engineering design company—gives it significant engineering relevance. The study likely includes validated process parameters and material selections that have been proven in actual soda ash production environments. Engineers in similar industries (cement, mining, power generation) can adapt the approach to their specific applications by adjusting material selection and process parameters based on their unique service conditions. The systematic approach to defect analysis and countermeasures provides a valuable reference for troubleshooting overlay welding problems in industrial settings. This work demonstrates that even in established industrial applications, systematic application of overlay welding technology can deliver significant improvements in equipment reliability and operational efficiency.