Effects of Synchronous Rolling on Microstructure, Hardness, and Wear Resistance of Laser Multilayer Cladding
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JMEPEG (2018) 27:1746–1752 https://doi.org/10.1007/s11665-018-3286-x
Effects of Synchronous Rolling on Microstructure, Hardness, and Wear Resistance of Laser Multilayer Cladding W. Zhao, G.C. Zha, M.Z. Xi, and S.Y. Gao (Submitted April 21, 2017; in revised form December 12, 2017; published online March 15, 2018) A synchronous rolling method was proposed to assist laser multilayer cladding, and the effects of this method on microstructure, microhardness, and wear resistance were studied. Results show that the microstructure and mechanical properties of the traditional cladding layer exhibit periodic inhomogeneity. Synchronous rolling breaks the columnar dendrite crystals to improve the uniformity of the organization, and the residual plastic energy promotes the precipitation of strengthening phases, as CrB, M7C3, etc. The hardness and wear resistance of the extruded cladding layer increase significantly because of the grain refinement, formation of dislocations, and dispersion strengthening. These positive significances of synchronous rolling provide a new direction for laser cladding technology. Keywords
laser multilayer cladding, microhardness, synchronous rolling, wear resistance
1. Introduction Industrial and technological progress has resulted in strict requirements of unique circumstances in some applications that single materials often fail to satisfy. As examples of single materials, titanium alloys are generally regarded as excellent structural materials that exhibit high specific strength and good corrosion resistance (Ref 1, 2). These alloys are widely used in aerospace and chemical engineering industries; however, these alloys are unsuitable for use as wear-resistant machinery parts because of their high friction coefficients (Ref 3-5). Titanium components or products can survive in a harsh working environment if surface-coated (Ref 6, 7). Therefore, the surface of these components must be modified without affecting the bulk because failures mostly begin on surfaces, and such modification is an economical and effective strategy. Among the suitable surface-modification methods, laser cladding (Ref 8-11) is an advanced surface-modification technology. In this technique, advanced coating materials with low dilutions and rapidly solidifying microstructures can be applied to material surfaces. However, directional solidification organization in laser cladding layer causes uneven mechanical properties (Ref 12). In multilayer cladding, the non-uniformity displays periodic variation, which is unfavorable for controlling stability during use. The surface mechanical reinforcement technique is important to improve the performance of laser cladding layers. It causes work hardening and microstructure variation of the
W. Zhao and G.C. Zha, School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing 211167, China; and Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing 211167, China; M.Z. Xi and S.Y. Gao, Insitute of Mechanical Engineering, Yanshan University,
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