Large-Area Wear-Resistant Alloy Clad Plate Weld Overlay Technology and Applications

Literature Overview

This entry, originating from the Harbin Welding Research Institute in 1990, represents one of the earliest systematic investigations into large-area wear-resistant alloy overlay welding on structural steel substrates in China. The research context was driven by severe demands in coal handling, mining, and material processing industries where carbon steel equipment suffered rapid abrasive failure. The authors—Qian Qiang, Bao Xiaobing, Cui Rong, and Huang Wenzhe—addressed the fundamental challenge of achieving uniform, defect-free overlay layers over large surface areas while maintaining metallurgical compatibility between the base metal and the hardfacing alloy.

Core Technical Points

The study focuses on several critical aspects of large-area overlay welding:

Substrate preparation: Surface cleaning and preheating protocols to ensure adequate bond strength between the carbon steel substrate and the overlay layer.
Overlay layer design: Multi-layer strategies to balance hardness, toughness, and bond integrity, typically involving a transition layer followed by wear-resistant layers.
Process selection: Comparison of submerged arc welding (SAW), electroslag welding (ESW), and manual metal arc welding (MMAW) for large-area coverage efficiency.
Residual stress management: Techniques to control cracking in thick overlay deposits on rigid substrates.

Typical Process Parameters for Large-Area SAW Overlay

Parameter	Transition Layer	Wear-Resistant Layer
Wire diameter	3.0–4.0 mm	2.5–3.5 mm
Welding current	500–700 A	400–600 A
Welding voltage	30–38 V	28–35 V
Travel speed	250–400 mm/min	200–350 mm/min
Flux type	Low-hydrogen basic	Low-hydrogen basic
Preheat temperature	150–250 °C	100–200 °C
Layer thickness per pass	3–5 mm	2–4 mm

Process Analysis and Engineering Practice

Large-area overlay welding presents unique challenges compared to localized hardfacing. The thermal cycle affects a significantly larger volume of base metal, increasing the risk of distortion and residual stress accumulation. The research emphasizes that for plates exceeding 2000 mm in length, a systematic welding sequence—typically a zigzag or back-step pattern—is essential to minimize warpage.

The metallurgical challenge is particularly acute when overlaying high-carbon martensitic or carbide-forming alloys (such as Cr-C-Mo or Cr-C-Ni systems) onto low-carbon steel. Dilution between the transition layer and the substrate must be carefully controlled. The study highlights that excessive dilution in the first overlay pass reduces the hardness of the final wear-resistant layer, while insufficient fusion creates a weak bond interface prone to spalling.

Common Defects and Countermeasures

Defect Type	Root Cause	Countermeasure
Bond-line cracking	High residual stress, poor fusion	Preheat to 200 °C, back-step welding sequence
Overlay spalling	Excessive dilution, poor interface bonding	Increase transition layer passes to 2–3
Surface porosity	Flux moisture, insufficient shielding	Flux drying at 300 °C for 2 h
Cracking in overlay	Rapid cooling, high carbon equivalent	Post-weld stress relief at 600 °C
Non-uniform hardness	Inconsistent deposition rate	Automated welding with constant current control

Study Insights and Implications

The 1990 research is notable for establishing systematic methodology for large-area overlay that continues to influence modern practice. The emphasis on transition layer design and welding sequence optimization remains directly applicable to contemporary applications such as bulk material handling equipment, crusher hoods, and conveyor components. The findings regarding residual stress management through controlled thermal input and post-weld heat treatment provide a foundation for modern FEA-based welding sequence optimization.

One key insight that deserves emphasis is the economic balance between overlay thickness and service life. The study demonstrates that beyond a certain thickness (typically 8–10 mm for moderate abrasion), additional overlay material provides diminishing returns because the remaining base metal governs the overall structural integrity. This principle remains critical in modern cost-benefit analyses for overlay applications.

The research also foreshadows current industry trends toward mechanized and automated overlay systems. While the 1990 work primarily addresses manual and semi-automated processes, the systematic parameter development approach is directly transferable to modern robotic SAW and electroslag overlay systems now used in large-scale manufacturing environments.