Original article J Strain Analysis 2019, Vol. 54(1) 54–64 Ó IMechE 2018 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0309324718819298 journals.sagepub.com/home/sdj Effect of secondary crystal orientations on the deformation anisotropy for nickel-based single-crystal plate with notch feature Yu Zhai 1 , Muhammad Kashif Khan 2,3 , Jose ´ Correia 4 , Abı ´lio MP de Jesus 4 , Zhiyong Huang 1 , Xu Zhang 5 and Qingyuan Wang 1 Abstract The effects of the secondary crystal orientations on the nickel-based single-crystal superalloy turbine blades were inves- tigated. The stress concentration features were used for investigation of the optimal secondary crystal orientation lead- ing to the higher strength of the single-crystal turbine blades. The crystal plastic finite element method coupled with micromechanics constitutive model is applied to study the effect of secondary crystal orientation on plastic deformation and mechanical behavior around the cooling holes and notches with the primary (load) orientation fixed at [001] direc- tion. For nickel-based superalloy plates with holes or notches, the secondary crystal orientation effect on the strength needs to be clarified at various load levels. The maximum von Mises stress in the single-crystal alloy varies significantly with variation in the secondary crystal orientations. It was found that only two slip systems dominate the deformation process of the material owing to their favorable orientation with loading. The secondary orientation of 45° was identi- fied with lowest resolved shear stress in the dominating slip systems and potential of producing higher strength for single-crystal turbine blades. Keywords Crystal plasticity, single crystal, secondary orientation, dominant slip system, resolved shear stress Date received: 27 September 2018; accepted: 23 November 2018 Introduction Jet engine turbine blades are subjected to complex ther- momechanical loading in the service life. Unlike the polycrystalline alloys, the single-crystal superalloys per- form extremely well under higher temperatures. Nickel- based single-crystal superalloys are widely used owing to their superior mechanical strength and resistance against creep, corrosion, and oxidation at high tem- peratures. The single-crystal blades operate reliably at very high temperatures by increasing the efficiency and safety of the engine. The anisotropic material proper- ties of single-crystal turbine blades may result in high localized stresses of the order of the yield stress when turbine rotates at high speed at elevated temperature. Single-crystal blades are manufactured by directional solidification, 1 and the primary crystal orientation in single-crystal blades varies up to 108 only. However, the secondary crystal orientations (SCO) vary significantly from 08 to 908. The turbine blades are usually fabricated with cooling holes which support the resistance against elevated temperature. However, Wang et al. 2,3 investi- gated the effect of circular hole size on the low-cycle fatigue (LCF) life of TA19 specimens and found the effect of stress gradient on the fatigue crack growth. The higher stress concentration around cooling holes or accidental scratches and notches results in premature 1 School of Aeronautics and Astronautics, Sichuan University, Chengdu, China 2 Institute of Future Transport and Cities, Coventry University, Coventry, UK 3 Department of Mechanical Engineering, DHA Suffa University, Karachi, Pakistan 4 INEGI, Faculty of Engineering, University of Porto, Porto, Portugal 5 Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province, School of Mechanics and Engineering, Southwest Jiaotong University, Chengdu, China Corresponding author: Zhiyong Huang, School of Aeronautics and Astronautics, Sichuan University, Chengdu 610064, China. Email: huangzy@scu.edu.cn