Zhuojin Pipe Fitting Co., LtdMicrostructure and Wear Resistance of Dissimilar Material Overlay Cladding
Literature Overview
This study by Liu Zhengjun, Song Xingkui, and Tang Xingtao from the School of Materials Science and Engineering at Shenyang University of Technology, published in the Transactions of the China Welding Institute (Hanxie Xuebao) in 2011, Volume 32, Issue 4, pages 99–102, investigates the microstructure and wear resistance of aluminum bronze alloy powder cladding on low carbon steel using plasma arc welding. The research employs a reverse-polarity weak plasma arc process and systematically examines how different welding parameters influence the cladding microstructure, hardness, and wear performance.
Process Parameters and Experimental Methodology
The study utilized a reverse-polarity weak plasma arc to clad aluminum bronze alloy powder onto low carbon steel substrates. Reverse polarity (AC with negative electrode) promotes powder melting and transfer, while the weak plasma arc provides concentrated heat input with minimal dilution. The experimental design varied key process parameters including current, arc voltage, powder feed rate, and travel speed to investigate their effects on cladding quality.
| Parameter | Effect on Cladding |
|---|---|
| Current | Higher current increases dilution and grain size |
| Arc voltage | Higher voltage increases arc diameter and dilution |
| Powder feed rate | Higher feed rate increases cladding thickness and reduces dilution |
| Travel speed | Higher speed reduces heat input and dilution |
| Polarity | Reverse polarity promotes powder melting |
| Plasma type | Weak plasma provides concentrated heat |
Microstructural Analysis and Wear Mechanisms
The cladding layer achieved metallurgical bonding with the base material, and the dilution ratio was low, which is critical for maintaining the desired alloy composition and properties. The microstructure of the cladding layer varied with process parameters. When the cladding contained a dense α phase or when the α phase precipitated along grain boundaries in a network distribution, the wear resistance was significantly improved.
The wear mechanism analysis compared the cladding layer against 45 steel counterfaces under friction and wear conditions. The results indicated that wear resistance is governed by a combination of factors including the microstructure of the alloy, the hardness of the cladding layer, and the characteristics of the friction pair. The α phase network along grain boundaries acts as a reinforcement that resists abrasive wear by impeding dislocation motion and providing hard phases that resist material removal.
Engineering Implications for Dissimilar Material Cladding
The low dilution achieved with the reverse-polarity weak plasma arc is a significant advantage for dissimilar material cladding applications. In many industrial scenarios, such as pump impellers, valve seats, and hydraulic components, the cladding material must retain its specific alloy composition to provide the required wear or corrosion resistance. High dilution from the base material can alter the microstructure and degrade the performance of the cladding layer.
The finding that α phase network distribution enhances wear resistance provides a microstructural design criterion for optimizing cladding process parameters. Engineers can adjust parameters such as travel speed and powder feed rate to promote the formation of grain boundary α phase networks, thereby maximizing wear resistance. This approach is particularly relevant for cladding applications where the base material is a dissimilar steel that would dilute and alter the cladding composition if not carefully controlled.
Summary
This paper provides valuable insights into the microstructural evolution and wear behavior of aluminum bronze cladding on low carbon steel using plasma arc welding. The reverse-polarity weak plasma arc process achieves low dilution and metallurgical bonding, while the α phase network distribution along grain boundaries significantly enhances wear resistance. The systematic investigation of process parameter effects on microstructure and wear performance offers practical guidance for optimizing cladding procedures in dissimilar material applications.