Thermal Relaxation of Residual Stress in a Carbon Nanotube Reinforced Aluminium Matrix Composite

Author:  Kaiyuan Zhu, Chuanhai Jiang,Vincent Ji
Source:  ICSP-13
Doc ID:  2017067
Year of Publication:  2017
Abstract:  
Introduction: Shot peening (SP) is an important method to enhance metallic superficial properties [1-4]. After SP,the introduced compressive residual field (CRS) and change of microstructure could improve the surface properties significantly [5-7], such as surface microhardness, stress corrosion property,fatigue life, ect [8,9]. Stress peening is a special and important shot peening method. It is mainly used in stress peening forming to fabricate thin parts with complicated shapes, such as sheet with double curvatures, aerofoils. In the process of stress peening, specimens were elastically prebended in certain directions for peening forming. And a CRS field, a critical parameter for the component, were induced by high energy “shots”. After stress peening, the prestresses were released and the CRS field was changed by elastic recovery. This change could be considered as a superposition of two stress fields: one is a CRS field introduced by SP, another one is a stress field generated by release of the prestress. Specially, for different materials, the CRS field was different with same peening parameter and prestress [10-15]. Recently, the CNTs reinforced aluminium matrix composites have attracted wide and growing attentions to develop a new generation of high-stiffness metallic, high-strength, lightweight materials [16-22]. Due to it would be used for the fields of the electronic and military devices, high speed transportation. In these fields, the new material might be formed by stress peening to fabricate some complicated shapes. After stress peening, the CRS field induced by stress peening should be retained or released by annealing treatment due to specific requirements. In addition, few investigations have been made on thermal relaxation of an anisotropic CRS field.