Zhuojin Pipe Fitting Co., LtdLarge-Area Wear-Resistant Alloy Cladding Plate Overlay Welding Technology
Literature Overview
This paper by Qian Qiang, Bao Xiaobing, Cui Rong, and Huang Wenzhe, published in the journal Welding (1990, No. 3, pp. 1-5), provides a comprehensive review of domestic and international large-area wear-resistant alloy cladding plate overlay welding technology. The authors, affiliated with the Harbin Welding Research Institute, focus on submerged arc welding (SAW) with powder filler metal as the primary process for producing large-area wear-resistant alloy cladding plates. This publication is historically significant as it represents one of the earliest systematic Chinese-language reviews of cladding plate technology, published during a period of rapid industrialization in China when wear-resistant components were in high demand across mining, cement, power generation, and material handling industries.
Technical Background and Process Selection
Large-area wear-resistant alloy cladding plates are produced by depositing a layer of wear-resistant alloy (typically 3–25 mm thick) onto a carbon steel or low-alloy steel base plate. The resulting composite plate combines the toughness and formability of the base material with the exceptional wear resistance of the overlay alloy.
The primary process identified by the authors is submerged arc welding (SAW) with powder (agglomerated or cored) filler metal. This process selection is driven by several factors:
- Deposition rate: SAW achieves deposition rates of 5–15 kg/h, far exceeding those of manual or semi-automatic processes, making it economically viable for large-area production.
- Weld quality: The flux blanket provides excellent protection against atmospheric contamination, resulting in clean weld metal with low gas porosity.
- Scalability: The process is readily automated, enabling continuous production of cladding plates in standard sizes.
- Cost efficiency: Powder filler metal is significantly less expensive than solid wire or rod, and the high deposition rate reduces energy consumption per unit of deposited metal.
Comparison of Cladding Plate Production Processes
| Process | Deposition Rate (kg/h) | Typical Overlay Thickness (mm) | Max Plate Size (mm) | Cost Index | Wear Resistance |
|---|---|---|---|---|---|
| SAW with powder | 5–15 | 3–25 | 3000×6000 | Low | Excellent |
| SAW with solid wire | 3–8 | 2–15 | 2500×5000 | Medium | Good |
| GMAW with flux-cored wire | 2–5 | 2–10 | 2000×4000 | Medium | Good |
| Oxy-fuel (flame) | 1–3 | 1–6 | 1500×3000 | Low | Fair |
| DCOG (dual-shield) | 4–10 | 3–20 | 2500×5000 | Medium | Excellent |
Overlay Material Selection
The authors discuss several categories of wear-resistant overlay alloys, each suited to different wear mechanisms and operating conditions:
Overlay Alloy Categories
| Alloy Type | Typical Composition | Hardness (HRC) | Wear Mechanism | Application |
|---|---|---|---|---|
| High-carbon martensitic | C 2–4%, Cr 5–10% | 50–60 | Abrasive (moderate) | Chutes, hoppers, conveyor components |
| High-chromium cast iron | Cr 20–30%, C 3–4% | 55–65 | Abrasive (severe) | Coal handling, cement grinding |
| Carbide-reinforced (WC) | Fe-Cr-C with 15–30% WC | 60–70 | Abrasive (severe, dry) | Pump impellers, valve seats |
| Carbide-reinforced (Cr3C2) | Fe-Cr-C with 15–25% Cr3C2 | 55–65 | Abrasive (wet) | Slurry pumps, mining equipment |
| Austenitic (Hadfield) | Mn 11–14%, C 1.0–1.4% | 20–30 (as-cast), 45–55 (work-hardened) | Impact-abrasive | Ball mill liners, excavator buckets |
The selection of overlay material must account for the specific wear mechanism (abrasive, adhesive, erosive, impact-abrasive), the operating environment (temperature, chemical exposure), and the required combination of hardness and toughness.
Process Parameters and Quality Control
The SAW powder cladding process requires careful control of several process parameters to achieve consistent overlay quality:
Key Process Parameters
| Parameter | Typical Value | Influence on Quality |
|---|---|---|
| Arc voltage | 25–35 V | Controls heat input and penetration |
| Welding current | 300–500 A | Controls deposition rate and bead width |
| Travel speed | 200–500 mm/min | Controls bead overlap and dilution |
| Flux/wire feed ratio | 3:1 to 5:1 (powder:wire) | Controls dilution and alloy content |
| Preheat temperature | 150–250°C | Prevents cracking in high-carbon overlays |
| Interpass temperature | 200–300°C | Controls solidification structure |
| Number of passes | 2–8 | Determines final overlay thickness |
A critical quality parameter in cladding plate production is the dilution ratio, defined as the percentage of base metal alloying elements dissolved into the overlay weld metal. High dilution reduces the hardness and wear resistance of the overlay by diluting the alloying elements with the base metal composition. The target dilution for most wear-resistant overlays is below 30%, and for high-alloy overlays (such as high-chromium or carbide-reinforced), dilution should be kept below 20%.
To minimize dilution, the following strategies are employed:
- Use a low-carbon or medium-carbon steel base plate rather than a high-strength low-alloy plate, as the lower alloy content reduces dilution of the overlay alloying elements.
- Apply a transition layer of lower-alloy composition before the final wear-resistant overlay layer.
- Use a lower heat input (lower voltage, higher travel speed) to reduce penetration into the base metal.
- Employ a flux with a high alloy content to compensate for dilution losses.
Engineering Applications
The authors document several industrial applications of cladding plates produced by SAW powder welding:
- Mining industry: Chutes, hoppers, and conveyor components in coal and ore handling systems experience severe abrasive wear from sharp mineral particles. Cladding plates with high-chromium or carbide-reinforced overlays extend service life by 3–5 times compared to unclad carbon steel.
- Cement industry: Kiln hood linings, preheater cyclone components, and mill internals are exposed to hot, abrasive cement particles. High-chromium cast iron overlays provide excellent resistance to this type of wear.
- Power generation: Coal mill components, fan blades, and dust collector hoppers in coal-fired power plants require wear-resistant surfaces. Austenitic (Hadfield-type) overlays are commonly used for impact-abrasive applications.
- Material handling: Conveyor rollers, scraper chains, and bucket components in bulk material handling systems benefit from cladding plate construction.
Study Insights and Reflections
This 1990 publication captures the state of cladding plate technology at a critical juncture in China's industrial development. The emphasis on SAW powder welding as the dominant process reflects the practical constraints of the era: limited availability of advanced welding equipment, the need for high productivity, and the cost sensitivity of industrial users.
Several observations from a modern perspective are noteworthy:
- The process parameters described in this paper remain largely applicable today, with the exception of increasingly sophisticated automated and robotic systems that have replaced manual SAW in many applications.
- The discussion of dilution control is timeless and remains a primary quality concern in cladding plate production. Modern research has expanded on this topic with computational modeling of dilution and advanced flux formulations that provide better alloy retention.
- The material selection guidelines, while based on the alloy systems available in 1990, provide a solid foundation that has been extended to include newer overlay materials such as laser-clad alloys, plasma-sprayed coatings, and thermally sprayed wear-resistant layers.
The paper's enduring value lies in its systematic presentation of the SAW powder cladding process, including material selection, process parameters, quality control, and industrial applications. For engineers working in wear-resistant component manufacturing, this publication remains a useful reference for understanding the fundamentals of cladding plate production.
Reference Value and Outlook
The technology described in this paper has evolved significantly since 1990, with the introduction of robotic SAW systems, advanced flux formulations, and computer-aided process optimization. However, the fundamental principles of SAW powder cladding remain unchanged, and the process continues to be the workhorse of large-area cladding plate production worldwide. The paper's emphasis on the integration of material selection, process control, and application requirements provides a framework that is still relevant for modern engineering practice.