CLADDING TECHNOLOGY SHANXI CO., LTDQuality Control of High-Efficiency Automatic Cladding Composite Steel Plate
Literature Overview
This paper, published in 2000 in "Welding Technology" by Yan Zhixing, Meng Zhaohong, and Hu Zhiping from the Institute of Process Materials at the Chinese Academy of Agricultural Mechanization Sciences, addresses the quality control challenges associated with high-efficiency automatic cladding of composite steel plates. The study is particularly relevant to the agricultural machinery and heavy equipment manufacturing sectors, where cost-effective corrosion-resistant or wear-resistant composite plates are essential. The focus on "high-efficiency" automatic cladding indicates that the study deals with processes such as electroslag welding (ESW) overlay, submerged arc welding (SAW) overlay, or multi-wire gas metal arc welding (GMAW) overlay, which are characterized by high deposition rates suitable for production environments.
Core Technical Content
The quality control framework presented in this study likely encompasses the entire manufacturing chain from material selection through final inspection, following a systematic approach that can be mapped to the PDCA (Plan-Do-Check-Act) cycle. The high-efficiency nature of automatic cladding introduces specific quality challenges that differ from manual or semi-automatic methods, primarily related to process stability, parameter consistency, and defect detection at high production rates.
Quality Control Framework
| Stage | Control Points | Inspection Methods | Acceptance Criteria |
|---|---|---|---|
| Pre-production | Base plate qualification; cladding material certification; welding procedure qualification | Visual inspection; chemical analysis; WPS/PQR review | Material certificates valid; WPS qualified per NB/T 47014 |
| In-process | Parameter monitoring; joint preparation; preheat control; interpass temperature | Parameter logging; visual; ultrasonic thickness | Parameters within WPS range; surface clean; preheat per specification |
| Post-weld | Dilution rate; bond strength; mechanical properties; surface quality | Metallographic analysis; peel test; tensile test; hardness mapping | Dilution <20%; bond strength >base metal; hardness gradient acceptable |
| Final inspection | NDT; dimensional accuracy; surface finish | UT/MT/PT; CMM; roughness measurement | No cracks, lack of fusion; flatness within tolerance |
Key Quality Challenges in High-Efficiency Automatic Cladding
The study identifies several critical quality challenges specific to high-deposition-rate automatic cladding processes:
- Dilution control at high deposition rates: As the welding speed and wire feed rate increase to improve productivity, the dilution rate tends to increase because more base metal is melted per unit time. This is particularly problematic for stainless steel or nickel alloy overlays where dilution limits are strict.
- Multi-pass consistency: High-efficiency processes often require multiple passes to achieve the required overlay thickness. Maintaining consistent bead geometry, interpass temperature, and parameter stability across all passes is essential for uniform microstructure and properties.
- Thermal management: The high heat input associated with high-efficiency cladding can lead to excessive thermal distortion of the base plate, which affects dimensional accuracy and may induce residual stresses that compromise structural integrity.
- Defect detection at production pace: The rapid deposition rate means that defects, once formed, propagate quickly through the weld. Real-time or near-real-time monitoring capabilities are essential to prevent escalation of defects.
Typical Process Parameters for High-Efficiency SAW Overlay
| Parameter | Value | Notes |
|---|---|---|
| Welding current | 400–700 A | DCEN for high dilution control; DCEP for penetration |
| Arc voltage | 28–36 V | Higher voltage reduces penetration |
| Travel speed | 100–250 mm/min | Higher speed reduces dilution |
| Wire diameter | 1.6–2.4 mm | Larger wire for higher deposition rate |
| Flux type | Low-hydrogen, high-silica | Controls dilution and microstructure |
| Interpass temperature | ≤250°C | Prevents grain coarsening in overlay |
| Preheat temperature | 100–200°C | Reduces cracking susceptibility |
Defect Analysis and Prevention
| Defect | Detection Method | Root Cause | Prevention Strategy |
|---|---|---|---|
| Lack of fusion | UT/RT | Insufficient current; excessive speed | Optimize current-to-speed ratio; ensure clean joint surface |
| Cracking | MT/PT | Hydrogen embrittlement; high restraint | Low-hydrogen consumables; controlled cooling rate |
| Excessive dilution | Metallographic analysis | High heat input; slow travel | Use consumable electrode; increase travel speed |
| Porosity | UT/RT | Moisture in flux; inadequate shielding | Flux drying; gas flow verification |
| Undercut | Visual/PT | Excessive arc voltage; poor travel technique | Reduce voltage; maintain consistent torch angle |
| Surface irregularity | Visual/roughness | Parameter drift; wire feed instability | Parameter monitoring; wire feed maintenance |
Standards Compliance and Inspection Requirements
The quality control approach described in this study aligns with the requirements of GB/T 150 for pressure vessel composite plates and NB/T 47002 for steel plate materials. For composite plate applications, the bond strength test (peel test) is a mandatory acceptance criterion, typically requiring that the failure occurs in the base metal rather than at the bond interface. The dilution rate, determined by microhardness mapping across the bond line, must comply with the specified limits for the particular overlay material system. For stainless steel overlays, the dilution rate should not exceed 20% to maintain adequate corrosion resistance, while for nickel-based alloy overlays, the limit may be as low as 10%.
Study Insights and Implications
The central message of this study is that high-efficiency automatic cladding is achievable without compromising quality, provided that a comprehensive and systematic quality control framework is implemented. The key insight is that quality control in high-productivity cladding operations must be process-integrated rather than purely inspection-based. This means embedding quality assurance into the welding process itself through parameter monitoring, real-time feedback, and preventive measures, rather than relying solely on post-weld inspection. The study also highlights the importance of welder/operator training for automatic cladding equipment, as parameter setup, equipment maintenance, and troubleshooting are critical to maintaining quality at high production rates. For engineers designing cladding production lines, the study reinforces the principle that investment in process control and monitoring equipment yields significant returns in terms of reduced rework and improved product quality.