The Effect of Quenching and Partitioning Heat Treatment on the Wear Resistance of Ductile Cast Iron
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JMEPEG https://doi.org/10.1007/s11665-020-04871-1
The Effect of Quenching and Partitioning Heat Treatment on the Wear Resistance of Ductile Cast Iron Zhi Wang, Baoxu Huang, Hui Chen, Changzheng Wang, Jie Ma, and Xingchuan Zhao (Submitted October 27, 2019; in revised form May 16, 2020) The quenching and partitioning (Q&P) heat treatment was applied to ductile cast iron. The wear resistance of specimens under different states was tested by reciprocating friction and wear tester. The microstructures of the matrix were characterized by optical microscopy, scanning electron microscopy, transmission electron microscopy and x-ray diffraction. The mechanical properties and friction coefficient were measured and the wear rates were calculated. After Q&P treatment, the wear resistance of ductile iron was greatly improved due to the increase in hardness. The analysis results of the worn surface show that the friction load and mechanical properties have a great influence on wear mechanism. From the friction properties and phase analysis of the Q&P-treated specimens, it was found that martensitic transformation occurs in the process of friction, which strengthens the matrix and improves the wear resistance. Keywords
ductile cast iron, friction and wear, martensite, quenching and partitioning, wear resistance
1. Introduction As a substitute for steel, ductile cast iron has been widely used because of its good combination of mechanical properties with low production costs. In terms of the matrix structure, ductile cast iron consists of ferrite and pearlite. Thus, its mechanical properties can be altered by the changing of pearlite content to meet requirements (Ref 1, 2). The main methods of changing pearlite content are alloying or adjusting solidification conditions (Ref 3, 4). Changing the matrix can help to further improve its mechanical properties, especially strength. Therefore, the heat treatment process is introduced. Austempered Ductile Cast Iron (ADI), which is produced after the material is quenched and isothermally held at an appropriate temperature, exhibits high strength and good ductility due to its bainite ferrite and a substantial fraction of high carbon stabilized austenite (Ref 5, 6). In recent years, researchers have applied Quenching and Partitioning (Q&P) heat treatment, which was originally applied to steel, to ductile cast iron (Ref 7-11). The ultimate microstructures after Q&P heat treatment contain partitioned martensite, bainite, residual austenite and fresh martensite (Ref 7). Therefore, the Q&P-treated ductile cast iron has similar mechanical properties to ADI (Ref 7-11). Q&P heat treatment was firstly proposed by J. G. Speer et al. (Ref 12-14) in 2003, which led to the development of the 3rd generation of Advanced High Strength Steels (AHSS) (Ref 15). The Q&P heat treatment process involves the quenching of austenite between the martensite start (Ms) and martensite finish (Mf) temperatures to produce a mixed matrix of Zhi Wang, Baoxu Huang, Hui Chen, Changzheng Wang, Jie Ma, and Xingchuan Zhao, School of
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